We're looking at the first probes to Venus in over 35 years

NASA's last long duration mission to Venus was the Magellan probe, launched in 1989 and ended its mission in 1994. Magellan was a radar mapping mission (Synthetic Aperture Radar) that never landed on the planet but generated the most complete, highest resolution, radar map of the planet long thought to be the one in our solar system closest to being Earth's twin - at least in size. Again, that ended in 1994, 32 years ago. 

There's a couple of satellites being prepared for missions within a few years. 

Two NASA missions are on track to launch to Venus in the early 2030s. The first, known as the Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI), is now scheduled for launch in December 2030, a year earlier than previously planned. DAVINCI will send a parachute-assisted descent probe through the atmosphere of Venus, returning the first direct images of the planet’s surface since 1982. A second mission, Venus Emissivity, Radio science, InSAR, Topography, And Spectroscopy (VERITAS), will follow with a launch in November 2032 to map the Venusian surface by radar from orbit.

The European Space Agency is building another orbiter, Envision, for launch to Venus in 2032. The Venus armada might get started as soon as next year, when Rocket Lab aims to launch a privately funded probe to search for signs of organic material in the planet’s clouds.

That comes from an update last week at a meeting of the Venus Exploration Analysis Group (VEXAG), a worldwide group of scientists focused on research of the planet.

There has been virtually no talk about any of these missions in the press I read; the vast majority of what gets talked about pretty much is split between Mars, the moon, and Earth observation, especially anything that can be linked to "global warming." If you've read anything about Venus, you'll know it's a rather hostile and difficult place to visit.

Venus is roughly the same size as Earth and may have once shared a similar climate, but something happened to turn it into an inhospitable world with an atmosphere made of nearly pure carbon dioxide, clouds of toxic sulfuric acid, and temperatures hot enough to melt lead, about 872° Fahrenheit (467° Celsius).

There’s still plenty to learn about Venus. The planet is less well mapped than Mars, and scientists aren’t exactly sure what triggered Venus’ runaway greenhouse effect. It is notoriously difficult to land on Venus, where the air pressure is 93 times that of sea level on Earth, equivalent to about 3,000 feet beneath the ocean’s surface.

While Japan and Europe launched orbiters to Venus in 2005 and 2010 with instruments to improve the Magellan SAR results from the 1990s, let's just say it apparently has taken around 30 years to get NASA onboard with doing this.

“The Venus community is absolutely elated and excited and wants to just get to work and see this happen,” said Ellen Stofan, a Venus scientist and under secretary for Science and Research at the Smithsonian Institution, in an interview with Ars at the time. 

The reality of the situation is that there is constant pressure to cut NASA's expenses, and no organization, no company, nobody can do everything that's a good and interesting idea. You might recall that the Mars Sample Return mission, expected to return samples gathered by the Perseverance Mars Rover and planned for during that whole mission development, was cancelled. It was simply too expensive to send another Mars mission over to pick up the samples. You'll find similar talk about all of these Venus missions. 

NASA’s planetary science budget remains under pressure. The Trump administration has twice proposed deep cuts in planetary science. Congress restored most of the funding for fiscal year 2026 and is expected to do the same in the 2027 budget.

Ending support for Europe’s Envision mission and canceling Mars Sample Return freed up enough funding for NASA to move forward with DAVINCI and VERITAS, and in some cases, buy back some of their past delays. DAVINCI is now targeting a launch in December 2030, a year earlier than the previous plan.

“Thanks to encouragement in early ’26 from our leaders at NASA Headquarters and the Planetary Science Division,” said Garvin, who leads the DAVINCI science team. “This is our new scenario for the most cost-effective and science-effective launch to Venus … What we’ve done now is accelerated launch by 54 weeks to a case where we have a very low delta-V trajectory that gets off the ground in late December 2030.”

At the moment, then, both DAVINCI and VERITAS have budget and support to get to their launch dates. VERITAS is targeted to launch in November 2032, the month after DAVINCI arrives at Venus. The two teams are working hard to get their missions to succeed. 

This Magellan (false color) radar image aligns with the surface features seen on WISPR images captured by Parker Solar Probe during its third flyby of the planet in July 2020. Image Credit: Magellan Team/JPL/USGS  The picture can be downloaded here.

[As an aside, I never cease to be amazed at programs with names like DAVINCI or VERITAS that come from acronyms of the most obscure sounding words or phrases you can think of. Which comes first? One would think the instruments and mission get defined, but I'm not convinced it doesn't turn into something like, "I need another 'I' to complete the name we came up with." ... "If we talk about imaging for the 'I', can we add something to do the imaging?"] 

A couple of SpaceX news items

First, about this morning's launch from Cape Canaveral's SLC-40 at 6:33, after writing last night's post I weighed getting up at around 6:15 for this morning's launch. The positive side was hope it would be an eye "candy" treat, while the negative was the fact that the launch was to the northeast and that's generally the worst launch direction for visibility to us here. Many times we get no more than a glimpse of a spot of light moving in the distance. The launch being 45 minutes or so before sunrise increases the chances of seeing that spot, but the prettiest launches to watch tend to be between east and south. Both of those are unusual, with southeast being the most common. 

So do I get up? Getting up to get ready for work isn't a concern but her majesty (Tyla the cat) wakes me up virtually every morning for breakfast the only question is when. I figured if she woke me up in time, I'd go outside. The law of "the general perversion of nature" therefore demands she wouldn't wake me up until well after the launch and that's exactly what happened. 

Luckily though, in this morning's email, commenter Ralph last night had emailed me a spectacular photo of the launch and something that I never thought about last night at all. These effects are called Space Jellyfish and this is probably the most photogenic one I've ever seen. 

Space Jellyfish - Image credit above ("commenter Ralph")

It's worth a little time in description because the three sections might not be what you think. The big, fairly oval-shaped whitish cloud with what looks like a six pointed star on the bottom left is the second stage carrying the payload and while it seems closer to us, it's the farthest away of the three main things you can see. The middle area that looks like a cotton ball or a bunch of loose threads is where the separating booster heading back to us and that second stage going away from us at the bottom both blew rocket exhaust into each other. At the top right, you'll see a sort of pointed triangle shape which is the booster heading back for its landing and reuse. It's still going up at that point in time, but eventually flies a planned trajectory to the recovery ship.  

I just wish I'd gotten up to see this. 

SpaceX launched the first Starlink mission from Vandenberg in over 3 weeks

That was last night (Oct 12) at 8:28 PM EDT 5:28 PM CA time and 0028 on Oct 13 UTC. Space.com points out this was the first such mission since September 19, three weeks and two days ago. That was a very long delay between Starlink missions based on the rates when they were launching from both coasts (Vandenberg SFB and Cape Canaveral SFS). Though they don't go into the reasons part of the reason must come from the transition from the Starlink versions 1 through 2 that the Falcon 9 can handle and the Starlink V3 satellites that need to be launched by Starship - or something rated heavier lift than the Falcon 9. The Falcon 9 seems to be the most phenomenal rocket ever developed, with 708 missions through last night, out of which 705 were successful, a mere 99.6%.

Back on the September 28 flight of Starship 14, the ship carried and deployed 26 Starlink V3 satellites.

This will happen many more times going forward, if all goes to plan: The Starlink V3 constellation will eventually consist of about 100,000 satellites, all of which will fly on Starship, Elon Musk has said. 

100,000 Satellites? What's that old song that says, "when you dream, dream big"?

Booster 1088 lands on OCISLY (Of Course I Still Love You) after last night's Starlink mission, the booster's 20th mission. Credit: SpaceX

Early Tuesday morning SpaceX launch to the ISS

Well before sunrise on Tuesday, 6:33 AM EDT with sunrise at 7:22 AM, SpaceX is set to launch a cargo payload of about 6300 pounds to the ISS. The mission is known as CRS-35 and, yes, the "35" means it's the 35th of these Commercial Resupply Service missions.

This mission will deliver the fourth pair of iROSA solar arrays which will be used to provide additional power to the station. 

The mission can be watched via NASASpaceflight (.com)  or via Space.com's link on NASA video on YouTube as well. The NASA Spaceflight video will start around one hour before liftoff, while the Space.com video starts quite a bit later 6:15 a.m. EDT (1015 GMT) or 45 minutes after NASASpaceflight.com's video starts. 

Not the last launch but a "file photo" of a 2021 Cargo Dragon launch (where "file photo" means the file is my Blogger account), CRS-21 mission lifting off December 2020 - SpaceX Photo

How 'bout some Holiday Weekend Memes?

I'm not sure how I didn't get to most of wanted to do today, but it was a "hey, why not?" kinda moment.

 One that I've loved since the moment I first saw it:

Note the logo on top right of the box for Glaxo Smith Kline drugs. This is genius-level artwork. 

How'd you like to find this file of miscellaneous forms where you work? Or at your doctor? Or...?

This is a different form but the subject is exactly the same joke my son and I would laugh over while he was starting out in Chemistry at Florida State University. That was about Y2K, so years before this story.

 

The season is coming for snow plow shoes 

 And finally

 

All I could think of.

On 10/10 day

October 10th, which is 10/10 both for the way Americans and the rest of the world write the date, could well mean more to hams than to "regular" people. Some of you are nodding in agreement already. 

Quick explanation, among ham radio's relatively strange habits is to refer to the wavelengths of various frequencies we're allocated by their metric lengths. The High Frequency spectrum is spread across the 3.0  to 30MHz frequency range, but there are more allocations above and below the HF band. Now, I don't personally have any radios that read out in wavelengths in metric or US numbers but that could be done. It just isn't done routinely. 

The general allocation of HF bands for hams in the US, given in meters is 80, 60, 40, 30, 20, 17, 15, 12 and 10 meters. It's not universally true that the bands we use contain any frequency for those wave lengths. Most of the time it's just "close enough" for someone naming it. When I was first licensed, in 1976, the bands labelled 60, 30, 17, and 12 meters weren't available to hams, it was just 80, 40, 20, 15 and 10 meters. 

For working far away stations, the higher frequency bands tend to propagate over longer distances due to using the higher F2 layer of the ionosphere. That means that when conditions are good, you'll hear places on 10 meters that are farther than you'll hear on lower frequencies. The other side of that is that more people will tune their rigs to 10m than when conditions aren't as good - also called "when the band isn't open." 

So some time ago - I really haven't found a summary of that today - a group of guys who wanted to try to encourage more use of 10 meters got together and started a club called 10-10 International and one of their "tricks" to get more people on 10 was to issue "Ten Ten numbers" which fed into contests and other activities on the air in which transmitting a receiving each other's 10-10 numbers was the way scores were determined. I got my 10-10 number early in my "ham life", July of '77.

Since today was 10/10 (until 7:59:59 PM in EDT), I thought it would be a good time to get on 10m and see if there was any activity going on where stations were swapping numbers. Bottom line: nope. In close to an hour tuning around the SSB portion and FT8 channel I heard and saw (read? "copied?") nobody giving a 10-10 number. In fact, I heard one other person and he was calling CQ from California.

Today's Planetary K index (K_P). The three tallest bars on the right include my time listening in. (Source, but you won't get this one, you'll get the one closest to the UTC time that you click on the link.) Was the dead band due to the Geomagnetic storm (G2 in the orange)? Could be. 

NASA issues RFP for private space stations

Today, Friday October 9, NASA released a Request For Proposals (RFP) to the US commercial space industry to develop private space stations that, as early as 2030, will succeed the International Space Station as a place for astronauts to live in low-Earth orbit.

In a cover letter accompanying the 360-page “request for proposals,” NASA stated its plan: “This will ensure NASA has a sustained human presence in LEO for crew members to perform science and exploration.” Several private companies that have worked for years on designing and developing such stations have been keen to learn exactly what capabilities NASA is seeking. These new documents finally provide some answers.

NASA’s solicitation can be found here. Industry responses are due back to NASA on December 8. NASA said it plans to select “two or more” contractors in this phase of the competition, and intends to make a final decision in April.

In a statement accompanying the RFP, NASA Administrator Jared Isaacman said they will never give up their presence in Low Earth Orbit. 

“We will continue to need a place to conduct research, develop technologies, train crews, and prepare for missions to the Moon and Mars. Commercial space stations may provide that capability while creating new opportunities for American industry and allowing NASA to concentrate more of our resources on the near-impossible missions ahead.” 

We can speculate which companies are likely to respond to this request. We know that Axiom Space, Vast Space, Voyager (Starlab) Space, and Blue Origin have all talked about putting up their own Space Stations, so those are probably most likely. The big question is the who the wild card will be - or if there will be several new wild cards.

On the mildly surprising side, SpaceX has not expressed any interest in Space Stations, so they're not expected to bid.

Which adds to the other big question: how will travelers get to and from this Space Station?

In earlier discussions with potential space station providers, NASA had indicated it may leave acquiring transportation to the contractors—basically saying it was their responsibility to sell an end-to-end service to the space agency.
...
But in the new request for proposals (RFP), the space agency goes further in support of would-be space station operators. As part of their bids, contractors do not need to provide proof of a signed contract with Boeing (or another transportation provider), or even a letter of intent. NASA is even offering to “furnish” transportation for the first four NASA service missions to the private stations, likely meaning it will help broker deals between the private companies and Boeing.

Artist's concept of the Vast Space Haven-2 space station. Image credit: Vast Space

That looks more like a "Space Station" than the Haven-1 we talked about almost exactly one year ago today.

The most important SW engineer that most people don't know passes

Ten years ago, in July of 2016, I ran into a story in an engineering magazine on the computer hardware and software used to help Apollo 11 become the first time people from Earth laid foot on the moon. Buried in that post is an introduction to someone who appears to have been the software creator behind the Apollo Guidance Computer, and much of the Apollo software, a young woman named Margaret Hamilton. 

Margaret Hamilton passed away last week at the age of 90. Ars Technica runs a biography of Hamilton today. Much of it resonated with me.

Margaret Hamilton, who coined the term “software engineering” and led the development of onboard flight software for NASA’s Apollo program in the 1960s, died last week at the age of 90. A recipient of the Presidential Medal of Freedom in 2016, Hamilton was also immortalized as a LEGO minifig the following year—part of the “Women of NASA” set that also included astronauts Mae Jemison and Sally Ride.

“To say Margaret Hamilton was a pioneer—to say she was ahead of her time—would be a dramatic understatement. She was a software engineer at a time when that field was in its infancy, and she not only developed advanced code herself but also led a team in using that nascent technology to develop one of the most complex systems humanity had ever achieved,” said Olivier de Weck, interim head of the MIT Department of Aeronautics and Astronautics. “The Apollo program still stands as one of our greatest testaments to the power of collaboration, ingenuity, and engineering, and Hamilton was a fundamental contributor to that program’s success.”

After graduating from Earlham College in 1958 with a degree in mathematics and a minor in philosophy. She married for the first time to James Hamilton, also in 1958. The plan was for her to work until he finished his law degree, after which he would support her through graduate school to earn a PhD in mathematics.

At this point, she ended up working for MIT Mathematician Edward Lorenz. If you've ever been around fluid mechanics, you're probably familiar with the term "Lorenz Equations" - he was trying to construct a mathematical model of the weather using a set of differential equations representing changes in temperature, pressure, wind velocity, and the like. You'll know that he discovered a problem with sensitivity, now widely referred to as "sensitive dependence on initial conditions," and considered a major impact of chaos theory.

You’ve probably heard the famous story of how Lorenz kept a continuous simulation running on his LGP-30 computer, and of that fateful 1961 day when he realized that even small differences in starting values could lead to very different outcomes—a sensitivity to initial conditions that is a hallmark of chaos theory, along with strange attractors. You might not have known that it was Hamilton who was responsible for programming the LGP-30. 

Computers were still pretty unusual things for scientists to work on. To borrow from that linked article:

(About the Royal McBee LGP-30.) This “desk” computer — it was the size of a desk — weighed some 800 pounds and sounded like a passing propeller plane. It was so loud that it even got its own office on the fifth floor in Building 24, a drab structure near the center of the Massachusetts Institute of Technology. 

There really weren't things like compilers they could have bought to take typed input and compile it into computer code. They had to invent that. 

Computers were still a novelty at the time, and neither Lorenz nor Hamilton had any programming knowledge; they taught themselves. Per a 2019 Quanta article, Lorenz was amused by her unusual methods: For instance, she once bypassed the “clunky debugging process” by rolling the paper tape down the hallway and editing the binary code by hand with a pencil. “I’d poke holes for ones, and I’d cover up with Scotch tape the others,” she recalled. Hamilton moved to another project in 1961, but not before training her replacement: a recent math graduate from Mount Holyoke named Ellen Fetter. Lorenz acknowledged the contributions of both women in his papers.

...

By 1965, Hamilton was all set to go to graduate school as planned when her husband spotted a newspaper ad saying that MIT’s Instrumentation Lab needed people to develop onboard guidance computer software for NASA’s Apollo program. She was the first programmer hired, and the first woman, working on six lunar landing missions from 1969 to 1972. At the time, binary code was stored using copper wires wound around cores. A “1” was a wire passing through a core, and a “0” was a wire bypassing the core. New England textile workers were hired to weave them together into long ropes, earning Hamilton the moniker “rope mother,” since she was responsible for those ropes.

Can you envision editing your code for a critical piece of software like that? A wire through or bypassing a toroid core? 

There's more to the story just in that Ars Article, and I'm sure more if I looked around a bit more. For example, at one point, Hamilton would routinely bring her daughter Lauren to the lab on nights and weekends. One time, the kid was playing around at a computer that was running software and entered something on a keyboard that crashed the system. While nobody was advocating for putting this sort of "idiot proofing" into the software for the Apollo missions, she could see it as a possibility with astronauts floating around in zero G with little control of their position. She asked NASA higher-ups if she could add a safeguard to prevent this from happening on an actual mission, but those higher-ups didn’t take it seriously.

Until astronaut Jim Lovell actually made an error like that during the Apollo 8 mission, the first to orbit the Moon, causing all the navigational data to vanish. Hamilton was called in to retrieve the data, jokingly referring to this as the “Lauren bug.” 

Hamilton in 1969, standing next to listings of the Apollo guidance software she and her MIT team produced. Image credit: NASA

By 1968 Hamilton was "assistant director in charge" of the Command and Service module software. She thought it would be a good addition to incorporate a failsafe into the system software’s “priority display” interface routines, should the onboard guidance computer become overloaded with more tasks than it could handle in real time.

That’s exactly what happened on the historic Apollo 11 mission in 1969. As the Eagle lunar module approached the Moon, Buzz Aldrin entered the codes to display altitude and other relevant data on the screen. The onboard computer started flashing alarms, forcing Mission Control to consider aborting the landing. Hamilton’s fail-safe meant that the computer was prioritizing essential tasks and canceling nonessential ones, and the alarm was to let astronauts know that this was happening. Thanks to Hamilton’s foresight, Eagle still safely landed on the Sea of Tranquility.

After the Apollo program, Margaret Hamilton worked in the same basic place, then called Draper Lab, until 1976. She went on to found two companies, Higher Order Software in 1976 and Hamilton Technologies in 1985. Its main product is the Universal Systems Language (USL) for developing complex software systems that prioritized error prevention and defensive programming. 

RIP Margaret Hamilton. Not everyone gets to say they left the world a better place than they found it. Many try. You achieved it.

SpaceX gearing up for 1st Starship launch from Florida

As you know, every Starship test flight, from the first tests that launched the ship by itself from the ground up to 50,000 feet to Flight Test 14 last Monday (Sept. 28) that made Earth orbit for the first time, every single launch has been from Starbase in Texas. They've also been working to expand that to Florida for years now, targeting the lunar launch complex, LC-39A, to launch the world's largest rocket. 

"Things are going super well at 39A," Julianna Scheiman, director of NASA science and Dragon programs at SpaceX, said during a briefing on Oct. 1 that primarily discussed that day's launch of the Crew-13 astronaut mission to the International Space Station.

The pad's new Starship launch tower is nearly complete, as is most other essential construction at the site, according to Scheiman.

"We've essentially done a lot of the initial build of the structures and the systems needed for launching Starship, and we're beginning to step into the sort of acceptance testing and operational testing prior to activation," she said. "So, we're kind of through the main construction and going into the proofing, testing — activation testing." 

Looking back on things from far on the outside, SpaceX began working on the LC-39A Starship facilities in late 2021, and that was probably a bit too early because I understand that the tearing down and rebuilding that has been pretty evident at Starbase Texas has been repeated here as well. It's only logical that Starship, the biggest rocket in world history, would require special work that isn't needed for smaller vehicles. LC-39A has launched Falcon 9 missions, manned and not, as well as Falcon Heavy missions. Those are not only smaller than Starship and the SuperHeavy booster, they don't even run on the same fuel as Starships. 

Falcon 9s - and the Heavy which is three Falcon 9s tied together - run Merlin engines which burn rocket-grade kerosene and liquid oxygen (or LOX). Starship runs Raptor engines, which burn liquid methane and LOX. That means the areas around the launch pad where the fuels are stored need to be able to hold lots of all them. That sounds like a Starship-friendly 39A needs a new tank farm. 

And here's the wildcard statement. 

SpaceX plans to launch at least one more Starship test flight from Starbase before flying the megarocket out of KSC, Scheiman said on Oct. 1 — meaning the first Florida Starship launch come come as soon as Flight 16.

The company has not yet announced target dates for upcoming Starship launches, but provisional planning documents identify Oct. 19 and Oct. 30 as possible "no earlier than" dates for Flight 15 and Flight 16, respectively. 

It's probably best to consider those dates, both Oct. 19 for flight 15 and Oct. 30 for 16 as aspirational goals they're working to meet, not commitments to launching on those dates. Still, a Starship launch before the end of '26 is two months after Oct. 30 and is still pretty darned exciting. 

I can't help but notice that there's a tie in between Starship and the Apollo missions. Pad 39A was the starting point for some of the most iconic Apollo flights, including Apollo 8 in December 1968 and Apollo 11 in July 1969.

This tradition will continue, if all goes according to plan: NASA picked Starship's Ship upper stage to be the first crewed lunar lander for its Artemis program, which aims to build a base near the moon's south pole over the next five years or so.

Ship is scheduled to fly for the Artemis program for the first time on Artemis III, a planned 2027 docking test in Earth orbit between the vehicle and NASA's Orion capsule. And that Ship liftoff will take place from Pad 39A, Scheiman said. 

Did you hear that SpaceX has submitted a plan to the FAA for approval of launching 76 Starship-Super Heavy flights per year from Cape Canaveral. There are more details related to that number. 

There's more pad work going on in Florida as well. Late last year, the U.S. Air Force gave SpaceX permission to fly Starship from two pads at Cape Canaveral Space Force Station, which is next-door to KSC. Those two pads — SLC (Space Launch Complex)-37A and SLC-37B — could eventually host 76 Starship liftoffs per year between them.

Don't forget that huge tract of land in Louisiana that will be the site of more launch pads. The source article on Space.com pretty much doesn't expect any launches from Louisiana until 2030, but they're certainly building with the intent to launch a lot more. Once a day? Once an hour? It's something to watch.  

Artist's concept showing two of SpaceX's Starship rockets at Cape Canaveral Space Force Station's Space Launch Complex-37. (Image credit: SpaceX)

That mission with the funny name still hasn't launched

I've devoted two posts to this already, so this will be short. The post with the most info on the launch was the second one, and posted on Sunday evening. To mercilessly copy myself,   

The mission, dubbed Tranche 1 Transport Layer A (T1TL-A), is the fourth mission sending production satellites into orbit for the SDA. This is one piece of a broad constellation — called the Proliferated Warfighter Space Architecture (PWSA) — designed to support the U.S. military and its allies through space-based capabilities, like missile tracking and secure communications.
...
The T1TL-A mission is one of 23 missions awarded to SpaceX as part of the National Security Space Launch (NSSL) Phase 2 contract awarded in August 2020, which is managed by the U.S. Space Force’s Space Systems Command (SSC). The previous missions from the SDA have already been launched:

T1TL-B – Sept. 10, 2025

T1TL-C – Oct. 15, 2025

T1TL-E – July 16, 2026

I see on NextSpaceflight.com that it's currently set for 3:54 AM EDT, on Thursday, Oct. 8th. While SpaceX has a web page for the flight, they don't say anything about why it didn't launch Monday morning, in particular, whether it was just a weather issue or a problem with the hardware; whether Falcon 9 or the payload. 

Rocket Lab signs largest launch contract to date

Aviation Week's Aerospace Daily & Defense Report part of Aviation Week Intelligence Network (AWIN), had an announcement from New Zealand launch provider Rocket Lab published last Thursday, October 1. 

Rocket Lab has signed what it calls its largest Electron launch service agreement to date, with a 20-mission agreement with Synspective. 

Synspective is the company behind the Synthetic Aperture Radars, like the one launched back on Sept. 18 (local time) covered here.  

Aviation Week added:

The Japanese synthetic aperture radar maker has already been a heavy user of Rocket Lab, with the latest agreement covering flights from 2028 through 2031. Synspective said it now has 47 launches booked with Rocket Lab, with 34 still to go.

The move comes days after Synspective said it was looking to deploy a second constellation to augment its StriX SAR satellites. The company now has 13 of its initially planned 30 satellites deployed, following a Sept. 26 Electron mission from Rocket Lab’s Launch Complex 1 in New Zealand.

“Securing another 20 dedicated launches now gives us long-term certainty for our constellation expansion,” CEO Motoyuki Arai said in a statement.

Note that the webpage says this is "complimentary through Oct 08, 2026." They are a news service that has long been subscription-only, so their willingness to publish things like this as complimentary is a bonus. Just know that if it's after Thursday, Oct. 08 the first link probably won't go anywhere. 

This is big gain for Rocket Lab. Most headlines about them have been focused on the larger rocket system they're developing, the Neutron, but Electron is their income stream and keeping them in business. The last thing I published about the Neutron was just over three weeks ago, August 11, and the focus was on their goal to launch the new rocket before the end of this year. While they didn't say anything like, "2026 ain't happening; the new date is ..." the deadline is squeezing them, but they haven't given up on it. I think everyone remotely associated with the launch industry is pretty aware that if you don't get it right, something really big blows up in your face. Preferably in front of a camera. 

A Rocket Lab Electron rocket launches a Strix Earth-observing radar satellite for the Japanese company Synspective on Sept. 18, 2026. (Image credit: Rocket Lab)

Back when I worked in the electronics sector that sold into the Department of Defense, today's AWIN was the publisher of a paper magazine called Aviation Week and Space Technology that's still there. The name the older guys used for that was Aviation Leak.

An interesting-sounding SpaceX mission early Monday morning Pacific time

I've noticed the mission being launched at 4:17:21 AM EDT (1:17:21 AM PDT) Monday morning for a few days, and mostly because it has "one of those kinds" of mission names that scream "too advanced for simple people like you". I'm sure it means something to the agency launching it but barely anything to the rest of us. To copy the name directly from NextSpaceflight dot com, it's "Tranche 1 Transport Layer A". Spaceflight Now is a bit less weird summary, simply saying, "SpaceX to launch 21 data transport satellites for the Space Development Agency."

Then they even "do some 'splaining' " for us.

The mission, dubbed Tranche 1 Transport Layer A (T1TL-A), is the fourth mission sending production satellites into orbit for the SDA. This is one piece of a broad constellation — called the Proliferated Warfighter Space Architecture (PWSA) — designed to support the U.S. military and its allies through space-based capabilities, like missile tracking and secure communications.
...
The T1TL-A mission is one of 23 missions awarded to SpaceX as part of the National Security Space Launch (NSSL) Phase 2 contract awarded in August 2020, which is managed by the U.S. Space Force’s Space Systems Command (SSC). The previous missions from the SDA have already been launched:

T1TL-B – Sept. 10, 2025

T1TL-C – Oct. 15, 2025

T1TL-E – July 16, 2026

...

The 21 satellites flying as part of the T1TL-A mission were manufactured by Northrop Grumman and delivered to Vandenberg Space Force Base on Sept. 28.

Tranche 1 is the initial component of the PWSA constellation is expected to begin providing operational capabilities to the Department of Defense beginning in 2027. When complete, T1 will consist of 126 Transport Layer satellites, 28 Tracking Layer satellites, and four missile defense demonstration spacecraft.

A row of Northrop Grumman’s Tranche 1 Transport Layer satellites are shown in a warehouse prior to launch on the T1TL-A mission. Image: Northrop Grumman

This will be the 6th flight of booster #B1103 on SpaceX's 117th mission of 2026 and will have a Return to Launch Site landing attempt around 7-1/2 minutes after liftoff. 

You can't accuse the Space Development Agency of the Space Force of being too small in their vision.   

The SDA said the Transport Layer will consist of between 300 to 500 satellites in low Earth orbit from 750 km to 1,200 km in altitude. The SDA said once complete, 95 percent of the globe will be in view of at least two of the T1TL satellites at any given time.

They're not aiming for tens of thousands of satellites like Starlink is but having 95% of the planet in view of at least two T1TL satellites is not exactly slouching.  

 

EDIT 10/5/2026 @ 1:35 PM EDT: The mission didn't liftoff this morning and is currently listed as NET 4:17 AM EDT Tuesday morning. The launch was scrubbed in the final minute of the count as rocket was shifting into its automated startup sequence. No more information has been released. 

Saying Good-Bye to what feels like an old friend

Within the last week I received news that a company I've been a customer of since around the start of this century is closing down. 

The company is Sherline Products, makers of wonderful machine tools that are on the small side, but excellent for making small, "hobby-sized" projects. They're still taking orders for parts, accessories and the tools themselves, but they say:

We plan to continue building and selling machines, tooling, accessories, and replacement parts to the extent our remaining equipment, materials, staffing, and inventory allow through the end of October.

Some manufacturing operations, particularly those requiring our larger production equipment, will necessarily end sooner as that equipment is removed from service.

Because availability will change throughout this transition, some products may become unavailable before others. We appreciate your patience and understanding as our employees work to fill as many orders as reasonably possible during these final weeks of production.

If you've read here for a while, I've talked about Sherline tools and my adventures with them many, many times. If I can grab a short summary from myself, something I posted in September of 2014...

I was one of those guys who kept saying "one of these days" I wanted to get a lathe and into metal working. Mrs. Graybeard took me up on that about 10 years ago [2004] and gifted me my Sherline 4400 micro lathe for Christmas. I had never actually touched any machine tools at all at that point, so to say I didn't know jack is an understatement. After playing with that lathe for 6 months, learning how to make some chips, and reading the Yahoo Sherline group (now at groups.io) regularly, an ad appeared for a CNC Sherline mill surplussed from a school system across the state in Tampa. After a 350 mile round trip drive, I pulled a CNC Sherline mill into my garage. The only problem was that nothing about it worked, except that the spindle motor turned. Like my lathe on its first day, this was the first time I had ever touched a milling machine.  

That first Christmas present lathe was was my introduction to Sherline, and the CNC Sherline mill my introduction to CNC. I eventually bought a "CNC Ready" Sherline lathe, and learned to thread on that before I learned to thread manually on the Sherline. Not threading but just changing diameters is "falling off a log" easy. I now have three lathes: big and small non-CNC lathes along with that CNCed Sherline. I have two milling machines in the shop. Plus the CNC Sherline milling machine and a bigger G0704 that I converted to CNC via online posts.

This barely touches my 20+ year experiences with Sherline, making everything from an AR-15 from an 80% lower to engines that run from bar stock, guitar parts and more. 

With Sherline having been a market leader that has been turning out good stuff for 52 years, I fully expect the vast majority of hardware needs we may have will have multiple sources. Right now, they're running a 25% off sale, bigger than any sale I can think of, so if you're an owner, spare parts are probably still available.

A screen capture of Sherline's home page taken 10/3/26.

Small Space News Story Roundup 87

After yesterday's "three in one day" it's gone back to being slow on news. But there's some

NASA to pay to upgrade ULA's Vulcan to be human rated

A side note to the stories on SpaceX shutting down Crew Dragon missions not too long after their 2030 missions is that if Starliner becomes the vehicle, it has only been rated to fly on an Atlas V, and United Launch Alliance is down to the last couple of those left to fly. ULA has just six Atlas V rockets left. One of them will be used for the uncrewed Starliner 1 test flight, and then five subsequent crewed missions.

NASA has reacted to the increased demands on Starliner, to ensure a path for its astronauts to the Space Station as SpaceX nears retirement of its Falcon 9 rocket and Crew Dragon spacecraft. That would make Boeing’s troubled Starliner spacecraft likely be the only commercial means of launching US crews to orbit. (Apparently, since there are no other vehicles that have gone through even the level of testing that Starliner has).

During a news conference on Monday, Dana Weigel, manager of NASA’s Low Earth Orbit Program, said the space agency would pay $359 million to Boeing to help the company complete a rebuild of the reaction control system thrusters that have overheated in flight. It would also certify United Launch Alliance’s Vulcan rocket for human missions. NASA also said it would exercise options to order two additional crewed missions on Starliner, bringing its total spaceflights on the vehicle to six. Any future Starliner flights beyond that would require a new rocket, like ULA’s Vulcan, as the Atlas V rocket is no longer in production. 

Blue Origin applies for a much higher launch cadence

Blue Origin, still in the process of rebuilding their launch complex (LC-36) on Cape Canaveral, in a draft environmental assessment released this week, seeks permission to significantly increase the vehicle’s launch rate from 12 to 50 per year. 

The proposal would include 50 launches of the rocket and 50 landings of the rocket’s first stage on a drone ship in the Atlantic Ocean. It would also allow up to 100 static-fire tests, one for each stage of the rocket for each launch. The proposal also covers recovery of the rocket’s payload fairing, which Blue Origin has not attempted on any of the three launches of New Glenn to date. 

Blue also has made mention of progress in the direction of the 9x4, (larger, more powerful) version of the New Glenn. 

A rendering of the 9x4 variant of a New Glenn rocket taking off. Image Credit: Blue Origin

Two down, one to go

A busy day even for SpaceX. 

The Crew-13 mission to the ISS went off on schedule, and apparently completely "by the book." While completely clouded out and unable to see or even hear a thing during the mission (11:10AM and for another eight to ten minutes), we watched it all on YouTube, through the Booster return to LZ-40 there on CCSFS. Within the last hour, Crew Dragon "Grace" docked with the ISS and the crew should have entered the ISS by now. 

The Transporter 18 mission from Vandenberg was during our grocery shopping run so we didn't watch that one live, but on YouTube when we got back and put everything away. Another one completely by the book, with every call during ascent on the expected time and flawless. The booster also successfully landed. I'll confess to boredom while watching the 130 satellites on the rideshare mission get deployed.

You will probably recall that Crew-13 was supposed to launch on September 12 but was grounded due to a leak in the Dragon capsule, specifically in the oxidizer system. In the intervening weeks, I've never come across an explanation of the problem and the fix SpaceX implemented. Until today. 

The launch was delayed from mid-September to replace a balky valve in the Dragon spacecraft’s propulsion system, a task that involved cutting into a propellant line inside the ship to swap out a faulty component. 

Bill Gerstenmaier, SpaceX’s vice president of build and flight reliability, pointed to the valve replacement inside the Dragon spacecraft as evidence of SpaceX’s commitment to fulfilling its contract with NASA. I think it's also evidence of SpaceX being extremely good at what they do. 

NASA announced a postponement for the Crew-13 launch in late August to give ground teams time to resolve an oxidizer leak inside Dragon’s propulsion system detected during launch preparations at Cape Canaveral. SpaceX traced the leak to a valve. The spacecraft was already loaded with nitrogen tetroxide, or NTO, the volatile, toxic oxidizer used by Dragon’s control thrusters in combination with hydrazine fuel.

Teams devised an unprecedented bit of spaceship surgery to replace the valve without draining the propellant and disassembling the spacecraft, steps that would have triggered a much longer delay. The fix involved cutting into the propellant line, removing and replacing the valve, then welding the line together again. It was the first time SpaceX has performed such a repair with a fully assembled Dragon spacecraft loaded with propellant.

“We looked at the plans, all of the data coming out of that, the welds, the leak, everything looks great,” said Dana Weigel, NASA’s program manager for the International Space Station. [We’re] really happy with how that repair was done.”
...
SpaceX’s preference to cut out the valve in place, rather than take a longer stand-down, kept the Crew-13 mission on track to arrive at the space station in time to replace Crew-12, which will return to Earth in mid-October after eight months in orbit.

The Crew Dragon spacecraft was inside SpaceX’s fueling and hazardous processing facility, known as Area 59, at Cape Canaveral Space Force Station, not at the company’s usual maintenance hangar a few miles away.

Because the Oxidizer tank was full of Nitrogen Tetroxide, a very reactive compound (which is why they use it, after all), Gerstenmaier said, “We had to get special permission from the [Space Force’s Eastern] Test Range to do these activities, to do ‘hot work’ with nitrogen tetroxide on the vehicle.” (I'll note that instead of NTO, some of you might prefer something closer to the standard chemical notation of N₂O₄ over NTO, as I do).

As for the third launch of the day, tonight's Falcon Heavy mission at 11:53 PM, at the moment I'm planning to watch this one online. We're still under the cloud cover we've been under all day and the forecast looks to be much like for the Crew-13 launch today. About a 60% chance of acceptable weather. 

A SpaceX Falcon Heavy rocket launches with NASA’S Nancy Grace Roman Space Telescope from Launch Complex 39A, just over a month ago, Aug. 30, 2026. Same vehicle on the same launch complex as tonight. (Image credit: NASA/Joel Kowsky)

Thursday October 1st to be a big SpaceX day on the coast

Tomorrow is going to be a big SpaceX day here on what's called Florida's Space Coast with two launches. The Crew-13 flight to the International Space Station is set for 11:10:06 AM EDT from SLC-40 (right - that's 6 seconds after 11:10 AM) and just under 13 hours later a rare Falcon Heavy mission is set to liftoff from Pad-39A at 11:53 PM. The two Falcon Heavy boosters will return to SpaceX's Landing Zones 1 and 2, while the core booster (all three are Falcon 9s) will continue to carry the payload, NROL-97, to orbital insertion. 

Crew-13 will launch NASA astronauts Jessica Watkins, Luke Delaney and crewmates Josh Kutryk ( of Canada) and Sergey Teteryatnikov (of Russia) on a six-month mission to the International Space Station. They will join three core members of the station's Expedition 75 crew, already aboard the station, as well as the four soon-to-depart meembers of NASA's Crew-12 astronauts, who will soon return to Earth on their own SpaceX Crew Dragon capsule. 

The Falcon Heavy mission Thursday night is to launch NROL-97, a satellite for National Reconnaissance Office (NRO); naturally, they won't say anything about the exact payload or its mission, but they have a pretty webpage with a picture of the mission patch and explanation of the symbology. 

The mission patch serves as a tribute to the lives and sacrifices remembered on September 11, 2001, embodying NRO’s unwavering commitment to protect our warfighters, defend freedom, and help build a safer world. The lighthouse characterizes enduring strength and the ability to provide information to those in need, even in difficult times. The endpoints of the light beam align to the locations of 9 and 11 on a clock face in honor of the 25th anniversary of 9/11. Four prominent stars represent the four aircraft lost on 9/11, and the moon phase is shown as it appeared on September 11, 2026. Download the NROL-97 Poster

The weather forecast for the missions isn't in the "nearly perfect" category but still better chances than random 50/50 odds. Space.com quotes, "forecasts call for a 55% change of conditions good enough to allow a launch." I just looked at the source and it's a bit higher (65%) but either number can only be considered a guideline - which is why the weather is monitored throughout the countdown. If Crew-13 does scrub tomorrow, the next launch window will be Friday (Oct. 2) at 10:47 a.m. EDT (1447 GMT).

Falcon 9 with Crew-13's Dragon stacked on SLC-40. Image credit: SpaceX.

Interestingly and unrelatedly, there's also a Falcon 9 mission from Vandenberg SFB between these two launches. The Transporter 18 mission, a SpaceX rideshare mission, lifts off at 2:18PM EDT. A busy day, even by the current SpaceX standards.  

Will Starliner become the replacement for Crew Dragon?

As we all settle back down to "normal" after Starship Flight 14, some news broke yesterday related to a big problem lying out there in the future somewhere. SpaceX has said they're going to retire Falcon 9 by 2030, and with it the Crew Dragon flights to the ISS. This is also going to impact another problem in economic expansion into space, one we talked about back in July: the world - probably surprisingly to many - is facing a shortage of launch capacity. Yes, the world is going to lose access to low cost Falcon 9 missions, including ridesharing missions that are the low cost leaders.

In the weeks before Flight 14 a story surfaced that Boeing and NASA were looking to resurrect Starliner as a work around for more flights to the ISS.

Yesterday, that story was updated on both Ars Technica and Space.com. Both state, without much specificity of date, that Starliner is going to do an uncrewed test flight sometime probably this coming December '26 or January '27. A crewed flight test is going to be needed but is more likely to fly in 2028. 

Back on Sept.18, the story broke that NASA had ordered three more SpaceX manned flights to the Space Station. 

On Friday, Sept 18, NASA awarded SpaceX $946 million to fly three more crewed missions to the International Space Station (ISS), a "period of performance" that runs through 2030. 

"As part of the agency's Commercial Crew Transportation Capability (CCtCap) contract, this change brings the total missions for SpaceX to 17 and helps NASA to maintain access to the space station with two unique commercial crew industry partners," NASA officials said in a statement on Friday (Sept. 18).

As we've talked about many times, at the start of the commercial crew program, NASA awarded a big contract to the company that everyone expected to do everything: Boeing. Since they were required to pick two contractors, they also awarded a contract to the brash startup, SpaceX, that had never done anything like developing a space capsule, man-rated, and capable of performing the missions. The score here in the fourth quarter is SpaceX has launched 13 crewed missions while Boeing has launched "zero point zero." Mission 14 is currently set for Thursday morning, October 1, at 11:10 AM EDT. It's all online chatter ("slop?") but every astronaut's comment I've read says the Dragon is a dream to ride in and to fly, while none of the other options (still including Russian Soyuz capsules and ground training simulators of Starliner) rate mention.

[NASA] has invested $5.1 billion to date in Boeing to develop the Starliner spacecraft. Despite this, Boeing has yet to fly a single operational mission to the space station. The news this week is that, despite these struggles, NASA will invest $359 million more to support the company’s efforts to fix Starliner’s propulsion system and certify the Vulcan rocket for new missions. It is NASA’s hope that Starliner can supplement astronaut missions during the remainder of the International Space Station’s lifetime, and then be available for private space station operators.

2021 photo of Boeing's first Starliner capsule to fly taken three years before the awful 2024 flight that was cut, turning a "two week" test to the ISS into nine months on the station for Butch Wilmore and Suni Williams. Image credit: Boeing

There are more aspects to this story. There are people advocating for another Commercial Crew program like the one that led to Starliner and Dragon. It isn't gathering lots of interest - my guess is NASA says they don't have the time for that. An outside chance is Blue Origin. Yeah, them. To quote from Eric Berger at Ars Technica:

The space company founded by Jeff Bezos is developing a “Space Vehicle” for astronauts to launch on the New Glenn rocket. After some of my recent reporting, sources reached out to let me know that design work is “well advanced” along with demonstration work such as cabin pressure-vessel manufacturing, extensive parachute testing, in-house thermal protection system testing, life support systems, and more. I’ve heard “no earlier than” dates of 2031 for a crew launch. But that’s probably optimistic, and if NASA and private space station operators need to book transport in the early 2030s, Starliner is probably the only option. 

Berger comes to the conclusion that if we need a replacement for the Crew Dragon, the most likely vehicle we know of to succeed is Starship. 

You’re probably not going to like this, but the only real hope for a significantly lower sticker price for sending humans into low-Earth orbit is Starship. If incentivized, SpaceX probably could bring this capability online by 2030 and radically reshape the market. But from all publicly available evidence, and based on private conversations, SpaceX seems unlikely to prioritize crewed ascent and reentry on Starship any time soon. Could that change? Certainly. Will it? Probably not. SpaceX and its founder, Elon Musk, will do what they want. 

Flight 14 shortened but still seemed to prove everything out

This morning's Starship Flight 14 had its launch delayed and a few glitches along the way that made them shorten the mission, but it sure seemed to prove out the big things they had listed for the mission. 

Almost two months to the day after the July 24th flight 13 which met or exceeded its goals, Ship 41 lifted off on top of Booster 21 from Starbase, Texas, at 8:49 am EDT (1249 UTC). While counting off milestones going by, SpaceX coverage noted that one of the 33 Raptor 2 engines had shut down fairly early in the flight, but the difference is small and the remaining 31 kept pushing the vehicle to orbit. A second Raptor 3, in the same ring of engines, shut down closer to Main Engines Cutoff, before stage separation. That's two Raptor sea-level engines out of 33.

After the stage separation, the ship looked better with all six of its engines working fine. Meanwhile the booster continued its return to a hovering stop off the beaches it had launched from. Much better than flight 13. The booster did appear to explode while standing vertically in the Gulf, but there is speculation that was the Flight Termination System commanding the detonation. 

Meanwhile the ship continued toward orbit, done by burning its six engines for around another five minutes. One of the vacuum raptor engines (larger engine bells) also shut down; the only noticeable effect of that was the system ran the engines a few seconds longer to achieve orbit. 

This led to the only endurance test for folks watching this one. Based on the performance of losing two of the booster's 33 raptors and one of the ships 3 vacuum raptors, SpaceX spent several minutes trying decide if they were going to do the orbital insertion burn or if they were just going to stay suborbital. It took on the order of 12 minutes before they decided it was a minimal risk and did the short (honestly, I think it was around two seconds) burn of just one of the three sea-level raptors. Then the team announced "nominal orbital insertion." 

SpaceX's 14th Starship test flight began with a Monday morning liftoff from Starbase, Texas. The city of South Padre Island is visible in the background, on the far (north) side of the Brownsville Ship Channel. Credit: SpaceX

Once in orbit, attention shifted rapidly to deploying the 26 Starlink 3 satellites that were the main goal of this mission. We watched them deploy the new version Starlinks, at a rate of approximately one every 65 seconds, using the same basic approach as they've used before, a system called a Pez dispenser. Honestly, calling it that is something that has always puzzled me. I mean, it doesn't look like any Pez dispenser I've ever seen. 

It seems looking back that it was very soon after the last Starlinks were released the NASA Spaceflight coverage started covering that SpaceX had decided the mission had proven enough and they would bring it down for a wet landing in the Pacific a little north of Hawaii. SpaceX's post-mission summary said, 

Out of an abundance of caution given the engine issue experienced during ascent, the flight control team decided to limit the duration spent on orbit and proceeded with deorbiting Starship to a splashdown location in the northern Pacific Ocean. This area was one of two pre-coordinated landing zones identified before launch that was cleared of sea and air traffic.

Starship then relit a single Raptor sea-level engine and performed its first ever deorbit burn. That maneuver successfully brought the vehicle out of orbit and sent Starship through atmospheric reentry and descent to the intended splashdown point.

Obviously, I don't have access to any inside information on SpaceX goals and how they set them, but it seemed to me that this went very well, just maybe not as well as flight 13. That might just be that both met or exceeded all goals but 13 achieved a few more. We have 93 days left in the year, and with 14 launching two months after 13, call that around 60 days. That makes it sound like we're more likely to get only one Starship launch than two launches before the end of the year. 

They have lots to do, but the pace of improvement has been picking up lately. This is where the problem of over-optimizing products comes in. They lost three sea-level raptor 3 engines? Has one part in those incredible engines been made a little too light, a little too thin? Only the people who spent the last decade (or however long) optimizing those engines would have a clue where to start looking. 

NASA Spaceflight has done a good summary video on the mission. It's about a 10 minute video and worth the time.

So what's a "synthetic aperture radar?"

So what’s a synthetic aperture radar (SAR)? I should take a moment to emphasize that this is all based on the mathematics of combining different signals. It’s essentially “Digital Signal Processing” (DSP) but on reflected microwave signals not audio from a microphone or other source. 

Take a look at the antenna in the previous post again. Each one of those dark spots is a cut out slot in sheet metal, like the dual of a wire on a mounting plate that’s not conductive. A properly sized, non-conductive slot, in a conductive sheet becomes the antenna. I talk about this in a post on aircraft antennas (of all things). It's in the portion below the line about 3/4 the way down the post. Especially the links on slot antennas. 

Consider these slots being cut for 10 GHz.  A quarter wave (90 degrees) slot’s length can be found by (antenna length - in feet) = 234/(freq in MHz)

L = 234/10,000 MHz = 0.0234 feet or 0.2808 inch

so a quarter wave is 0.281 inch and each of those slots is positioned on the sheet so that the E- (electric) fields combine to produce the desired radiation pattern. You’ll note that in some parts of the (more or less) circular outline of the plate, particularly along the left and right sides (in the picture), the slots seem aligned so that any four slots look like a square, while closer to the center, they don’t look to be aligned that way. The squares look cattywampus, to use the southern word. 

Remember the radar is on a moving satellite, and since the satellite's pointing the radar down on the weather, it’s moving fast, but not toward or away from the weather – it’s moving at right angles to the ground on Earth. That’s an approximation, but good enough for now.

The motion of the radar source causes a Doppler shift, the change in returned frequencies higher as radar approaches the reflector and lower as the two bodies separate. It’s hard to catch this from all these mentions of speeds and distances involved, but the reflected wave reaches slots on the antenna different from the ones they were transmitted from because of the satellite's speed in orbit and the time for the radar to get to the ground and bounce back up to the antenna. "Radar reflections from discrete objects in a passing radar beam field each [have] a minute Doppler, or speed, shift relative to the antenna"  

Carl Wiley, working at Goodyear, Arizona, (which later became Goodyear Aerospace, and eventually Lockheed Martin Corporation) in 1951, suggested the principle that – because each object in the radar beam has a slightly different speed relative to the antenna – each object will have its own Doppler shift. A precise frequency analysis of the radar reflections will thus allow the construction of a detailed image

Colburn, Robert (10 March 2009). "Your Engineering Heritage: Synthetic Aperture Radar". IEEE USA InSight IEEE.

In order to realise this concept, electromagnetic waves are transmitted sequentially, the echoes are collected and the system electronics digitizes and stores the data for subsequent processing. As transmission and reception occur at different times, they map to different small positions. The well ordered combination of the received signals builds a virtual aperture that is much longer than the physical antenna width. That is the source of the term "synthetic aperture," giving it the property of an imaging radar.[5] The range direction is perpendicular to the flight track and perpendicular to the azimuth direction, which is also known as the along-track direction because it is in line with the position of the object within the antenna's field of view. 

An illustration of the aperture synthesized - each of the long rectangles is depicting one of the antenna slots in the antenna we show. The motion of the antennas is along the X direction, left to right. 

How About an Intro to Radar?

Back last week, while talking about Rocket Lab launching a Synthetic Aperture Radar for the Japanese, I wrote, 

I used to design radars among other things, and when I thought of the questions being asked, my reaction was, "should I devote some time to things like the basics of what Synthetic Aperture Radars are and how they work?" Comments? 

Comments were in favor of doing that, so I decided to get started. It was starting to look like a long piece, so I started by putting together first a general introduction to radar, primarily to ensure everyone has a common language. 

---

RADAR 101

To me, it’s always stretching myself to take something as involved as radar can be – the word is applied to many different kinds of systems – and write a generally understood text on it.  At root, radar isn’t new; it was known before WWII. The name itself comes from radio detection and ranging. As the name implies, radars use radio waves to determine the distance and velocity (motion) of the targets they hit. 

Radio is ultra low frequency light – and since wavelength is inversely related to frequency, radio waves are much longer than light waves. There are aspects of the frequency chosen and the intended use for the radar, and those are “beyond the scope” of this. That means a radio frequency (RF) source needs to generate the radio waves to use. How are they detected? With a radio receiver, tuned to the frequency of the source. That’s intentionally vague because the bandwidth required for the receiver depends on what the radar is being used for. 

Finally, how is ranging detected? The easiest thing to envision is radar sending a single pulse on a single frequency, and in this case the range is determined by measuring the time between the pulse being sent and the pulse caused by its reflection off the target arriving back at the receiver. That time difference between being sent and received is divided by two to get the time distance to the target. Divided by two because the pulse has gone from the transmitter to the target and back to the receiver and each trip to or from takes the same amount of time. 

All radio and light waves travel at the same velocity, the speed of light, usually referred to as c in physics books. The speed of light is 300 million meters per second (formally 299,792,458 m/sec, but 3*10⁸ or 300*10⁶ m/sec is close enough for now). Which is the same as 300 meters in one microsecond (millionth of a second). If you’re more comfortable in miles, that’s 186,282 miles per second – or 0.186282 miles per microsecond (millionth of a second) which turns to be 983.664 ft/msec.  

Just bear in mind that if you get your return pulse in 1 µsec, it’s not 300 meters or 984 feet away. It’s half that because the pulse had to go twice that distance – half a µsec out and half a µsec back.

You can probably see from this how timing became very important in radar systems, but you may not see how timing became important in the antenna design. You see, every antenna that’s directional requires phasing differences between the elements of the antenna to establish patterns, whether it’s a simple yagi antenna with “a few” elements or a phased array antenna with dozens of elements, phasing is a mechanical way of establishing a timing difference. 

An easy Rule Of Thumb to remember is the more antenna elements you have the smaller and more concentrated your beamwidth will be. It’s why a yagi with seven elements will perform better than one with five or three. That is, the five element yagi will outperform the three, and the three will outperform a single dipole. Such an antenna will deliver a greater percentage of your transmitter’s output power onto a target and simultaneously deliver less power outside its beamwidth. Since part of the first sentence includes saying the smaller and more concentrated your beamwidth can be, that means the uncertainty in the direction the radar’s antenna is pointing goes down as the number of elements goes up. 

If this is new or puzzling, I've written a lot on this. See my post on, “A Ham Radio Series 31 – Phased Arrays, or A Dish Without A Dish” or “A Ham Radio Series 31 – Very Directional, Very High Gain Antennas”

How do these arrays of small antennas operate and produce patterns of gain that produce more signal in the desired direction? The phase differences between all the antennas combine to produce more gain in some directions and less in other directions. When antenna gain is measured and talked about, the antenna isn’t amplifying the signal; that requires active devices and electrical power. Antenna gain is measured in comparison to a defined antenna, usually a dipole or something more omnidirectional (transmits the same power in all directions). What the antenna is doing is combining the output of all the smaller antennas it's made of into one much higher power in one small angular width.

In optics, a telescope like the (78 year old) Hale telescope on Mount Palomar, the aperture of the single primary mirror, 200 inches, is the telescope’s aperture. In multiple mirror telescopes like the James Webb Space Telescope, combining the image data from several smaller optical instruments to generate an image as it would appear to a much larger mirror is referred to as the size of the combined image generating mirrors. In the case of the Webb (JWST) that aperture is a 6.5-meter-diameter (21 ft) mirror. Aperture for a radio telescope is the width of the antenna beam at a defined distance from the antenna. It's practically never talked about, but sometimes is mentioned in radar systems talk.

Because these high gain radio antennas approach having all of their gain in one direction with no signal transmitted or received from other directions, we’ve achieved the definition of radar.

Remember radar =  radio detection and ranging? The reflected radio pulse tells us something was detected, the time between the transmission and reception of the pulse tells the range, with the bonus of not just knowing “something’s out there” but the position of the antenna tells us the direction of that thing. If that radar is on something that’s moving, ship, car, airplane, or whatever, the motion of the vehicle and its position is constantly changing so that has to be incorporated in the calculations, too.  

Searching with Duck Duck Go for "Boeing 787 Weather Radar" because I've seen those. I found this and wanted to point out that the circular thing behind the nose with straight lines near the edges is the radar antenna array. Each of those small dark lines on the flat surface is an antenna, and the position of each one, along with how the radio signal gets to the antenna determines the antenna's pattern. 

EDIT 09/28/29 1325 EDT to correct a wrong prefix, changing 1msec to 1µsec - millisecond to microsecond. Thanks to commenter Lowell for pointing that out.