How can you not love the headline that Ars Technica used today? “Voyager 2 phones home and says everything is cool.” I guess it didn't take until October, like we talked about last Friday.
In an update to last Friday's message about having lost contact, JPL wrote:
The agency’s Deep Space Network facility in Canberra, Australia, sent the equivalent of an interstellar “shout” more than 12.3 billion miles (19.9 billion kilometers) to Voyager 2, instructing the spacecraft to reorient itself and turn its antenna back to Earth. With a one-way light time of 18.5 hours for the command to reach Voyager, it took 37 hours for mission controllers to learn whether the command worked. At 12:29 a.m. EDT on Aug. 4, the spacecraft began returning science and telemetry data, indicating it is operating normally and that it remains on its expected trajectory.
All of this indicates the probe is healthy, on course, and operating normally. To those who grew up with the Voyager "grand tour of the solar system" completed, and even to some of us who grew up before the two Voyagers launched a few weeks apart in 1977, it can be hard to internalize how much Voyager changed our mental images of the outer planets from before their missions.
Prior to the launch of Voyager 1 and 2 in 1977 on two different rockets, humans had been gazing at fuzzy blobs in the outer Solar System for hundreds of years. Pioneer 10 and 11 provided some better views of Jupiter and Saturn, but still, very little was known about the planets or their moons. Next to nothing was known of Uranus and Neptune. The Voyagers uncovered complex planetary systems and incredible moons, such as volcano-covered Io, icy Europa, and Titan, with its methane seas.
I went looking for a photograph of Jupiter or Neptune from one of the big observatories from the 1960s. No joy. I think I'll have to go to a library and look in old books. A look at something from one of the great observatories alongside a photo from one of Voyagers could be interesting.
Voyager 2 with its launch fairing being installed, 1977. NASA/JPL photo.
Let's make it a TwoFer
Word has been getting out that the Ingenuity helicopter on Mars has taken its 53rd flight and is being prepared for its 54th. Let me remind you the goals for the mission were first to be able to fly and then to take five test flights.
The Ingenuity drone flew on July 22 on Mars, achieving Flight 53. According to the Ingenuity flight log, the helicopter fly [sic] horizontally and north across 468 feet (142 meters) of Martian terrain with air time of roughly 75 seconds. Ingenuity soared roughly 16 feet (5 meters) into the air and achieved a top speed of 5.6 mph (2.5 meters per second).
The current goal for Ingenuity is to act as a scout for the Perseverance rover, which carried Ingenuity to Mars. Together, they're searching for interesting sites to collect samples from, to be loaded on a future mission to bring the samples to Earth.
Yay! It's amazing that they keep working and working and working.
ReplyDeleteAnd, yes, a comparison from a variety of earth-bound telescopes, then Voyager, then Hubble, all the other probes, and other newer space telescopes would be wild. Make it a 'slide' video and watch the planets get more and more defined over the years.
Hey, anyone at JPL! This is a rather excellent suggestion on Sig's part. Please do this!
I'm glad somebody somewhere finally remembered that antenna patterns don't go to zero at the 3dB line (I presume you read the whole article, explaining how they fired a high power message at it from Oz). If your receiver is down 6dB, well, then increase your transmission power by 6dB. If it's pointed further away, sneak in through a sidelobe. Simple. Radio beams aren't shaped like pencils.
ReplyDeleteBeans: I've seen videos like that on YT. Here is one:
https://www.youtube.com/shorts/H3t9VN5qmgg
While the patterns aren't pencils, a 70m dish is a lot more like a pencil than the one on Voyager. My SWAG is they spent time trying to understand how much more power they'd need to command V-ger.
DeleteThe first line in the 8/1 update from JPL was Using multiple antennas, NASA’s Deep Space Network (DSN) was able to detect a carrier signal from Voyager 2. It doesn't say multiple identical antennas, which would have given them 3 dB more receive signal, but I'm sure they new how much antenna gain they picked up. The same update doesn't say they'd use two antennas to transmit, but they'd know from the extra antenna gain, how much more transmitter power they'd need.
As I understand it, Voyager's power is going to run out in two years anyway, so sadly they don't have all that much more time to talk to it.
DeleteThe number I've heard is '25 with a "maybe" on that, but I've also read nobody's ruling out making it to the Golden Anniversary in '27. I wouldn't bet on that, but it would be neat to see one of them make it.
DeleteIt's almost like we could design stuff better in the 1970s - at least in terms of longevity - than we can today. The disposable society goes to space?
ReplyDeleteMalatrope, I can't remember the end of the line for Voyager, but the isotope packs have been getting weaker for some time. 1979 to 2025 is pretty damn good though. I was told that my LED lights would last 8 or 10 years, and I haven't seen one last 5 so far.
So is it more power which overcomes attenuation? I thought space is noisy with waves in every spectrum pinging 'round the universe.
ReplyDeleteObviously, I know nearly zero about radio. Nothing at all about shouting 12+ Billion miles.
How do they do it? Its not like they had experience with such great distances in a radioactive cosmos. Besides, back then they didn't expect Voyager to remain active for this long. And certainly not to continue comms for this length of time and distance.
Pretty amazing stuff.
This is hard to talk about in the little space here. Space may have waves going throughout the spectrum but the one thing those waves aren't is strong. Not always. Not all of them. The radio telescopes that measure these things are generally working with sources so weak they need to chill their receivers (especially the "front end", the circuits closest to the antenna). They sometimes chill them with liquid helium, which is pretty much the coldest liquid there can be, like 4 degrees Kelvin.
DeleteThe answer to the first is question is yes. More power overcomes the signal lost by the antennas not being pointed properly at each other. The extra attenuation, or signal loss adds into what's called "path loss". Path loss starts at one end and adds up every gain and every loss from the transmitter's output to the receiver's input.
It might be helpful to look at this old article about path loss with some numbers. Approximate, not official, but seem to match the real world.
SiG, thank you. That was enjoyable following all the links.
DeleteThank you for your ability and interest in sharing your knowledge.
And, it would be remiss not to mention, thanks for presenting a venue for the other knowledgeable people.
I dare say they amplified the signal. Amplify, amplify, amplify.
ReplyDeleteMake it boom, Vger is bound to receive it. If not, we tried.
But how without knocking the ears off sats in LEO?
Waves are not like pencils. But close enough to the emitter (LEO is plenty close), the shout could squirrel between orbits, therefore not affecting other sats.
DeleteThat's my WAG.