Randy Walden, director of the Air Force Rapid Capabilities Office, said the upcoming X-37B mission will be the first to use a service module to host experiments. The service module is an attachment to the aft of the vehicle and “enables us to continue to expand the capabilities of the spacecraft and host more experiments than any of the previous missions,” he said in a statement.Hmm. The concept of putting enormous photovoltaic panels in space, converting the solar power to microwave energy and beaming it down to huge arrays of antennas on the ground has been out there for at least a couple of decades. Usually referred to as Space Based Solar Power, it has become a stated goal for Japan, China and Russia. I used to call it "the Microwave Design Engineers' Full Employment Act."
One of the experimental payloads is FalconSat-8, a small satellite developed by the U.S. Air Force Academy and funded by the Air Force Research Laboratory. The FalconSat-8 will carry five science payloads. There are also two NASA experiments to study the results of radiation and other space effects on a materials sample plate and seeds used to grow food. A U.S. Naval Research Laboratory experiment will transform solar power into radio frequency microwave energy which could then be transmitted to the ground.
There are sound reasons to do that. First of all, the atmosphere doesn't pass all the energy that solar panels in space would get. In addition, space-based solar panels aren't subject to the big efficiency killers that ground or roof-mounted panels are affected by: windblown sand and dirt, or bird droppings. To ensure the power beams are safe enough to walk through or for aircraft to fly through, the power per square meter has to be the levels that safety authorities already approve. Or the system architects have to provide good arguments why it can be higher, presumably by ways of keeping people out of the energy beamed down.
This is the first experiment I've heard of to validate the concept.
By the way - that second quoted paragraph might well be the most the Air Force has ever said about an X-37B mission, especially in advance of the mission. The X-37B is the "mini-space shuttle" clone that was developed before the shuttles stopped flying, with its first mission in 2010. The craft has put in very long duration missions.
The design and landing profile of the X-37B — weighing about 11,000 pounds and nearly 29-foot long — is similar to NASA’s Space Shuttle but it’s one-fourth the size. The most recent mission OTV 5 was launched Sept. 7, 2017 on a SpaceX Falcon 9 rocket from NASA’s Kennedy Space Center. It landed on October 27, 2019.
X-37B, Boeing photo.
Taking a look at the long range forecast, don't plan a trip to Central Florida to see this launch. Next Saturday looks to be rainy all day.
The X-37B has had some very successful military-based missions. It took over some of the shuttle load, but there is a lot that you can't do without manned missions. Maybe one day, the Big Beautiful Space Force can take the high ground again.
ReplyDeleteIIRC, FALCONSAT will have an Amateur Radio transponder on it.
ReplyDeleteI wonder, as successful as the X-37 has been, why Boeing went with a version instead of their CST-100 capsule. Or at least made a man-rated version of of the -37 in addition to the CST-100.
ReplyDeleteWeird. Have a successful design and not develop it.
I would guess the answer is that adding life support equipment and the redundancy it requires would force a redesign.
DeleteThe CST-100 looks more like a scaled up Apollo capsule.
If the energy is safe enough to walk through, then it won't do a whole lot of good, will it?
ReplyDeleteThere is an older SF term for space-based beamed power: "Death Ray".
The key is that safety is based on Watts in a given area. Say it's microwaves where the safety limit is 10 milliWatts per square cm. That means the area gathering the power has be square kilometers. A square kilometer is 10 billion square cm. That's 100 megawatts.
DeleteMicrowaves are weakened by clouds, but not as much as sunlight is - depending on frequency. That implies making the square miles of antennas in a field in the desert SW or the other places that are premium for solar collectors.
You're an antenna guy, so you may know this:
DeleteIs it possible for an antenna to absorb more energy from a passing wave than travels through the cross section of the antenna? (Some sort of destructive interference, maybe, between the wave and the radiation from the currents induced in the antenna...)
Or can an antenna only absorb from its physical cross section?
(feels like something I should know by now, but...)
MadRocketSci
Absorb more energy than the wave going past it? I don't see how. There are antennas that absorb more energy compared to other antennas - that's referred to as antenna gain. As always, TANSTAAFL, and it costs. Generally arrays of wire or tubes that all intercept energy and direct it to the receiver.
DeleteThe extreme would be a dish antenna with a reflector - either sheet metal or wire screen - concentrating the incoming wavefront onto a feed assembly. The collecting area is much larger than available with metal tubes or wires, and that gets shoved into the feed. That's generally bigger than a wire as well.
Well, faraday cages wouldn't work if the latter was true. Now to figure out the details.
ReplyDeleteHigh frequency microwaves are cm to mm though - you'd need quite a dense antenna-mesh to capture it all. That speaks to the need for concentrated receiving stations, not the diaphanous spread-out line antennae in the artists depictions.
MadRocketSci
Jerry Pournelle was a proponent of this and followed developments in the field. IIRC, he described an experiment that transferred KW's of power some tens of miles at relatively high efficiencies. This was more than 10 years ago.
ReplyDelete