OK, it’s after lunch, and we’re about to watch a video about what the Army hopes it will be doing in space in the year 2035. We’re being told it’s not classified in any way. Nor does it discuss cost or difficulty of what we’re about to see…
It seems to be a CGI movie depicting rapid redeployments of advanced satellites (using something that looks a lot like QuickReach). It shows convoy routes planning a “virtual corrider.” Mobile user ground stations are deflecting attempts at GPS jamming. A “near-space platform” geolocates a terrorist unit. Noncombatants are identified, the house is surrounded, and the perps captured. The space vehicles depicted are dirty and gritty like the tanks. Like Serenity, in fact. Showing overhead imaging for battle damage assessment. “Understand First.” “Act First.” In other words, get inside their OODA loop.
Anyway, Jay Penn is up now, describing five different powersat concepts that Aerospace has been working on. This was work done for Joe Howell at Marshall and John Mankins at NASA. It consisted of a lot of system/subsystem level trades for comparisons and as inputs to technology roadmaps.
Showing several different concepts, the most different of which is called a “Halo”, which has a central transmitter surrounded by what seem to be mirrors for light concentration. But he’s going too fast for me to follow. A flurry of charts showing trade analyses and relative costs.
Some of these concepts imply flight rates of 5000/year. Notes that 40% of the global economy is energy. The best costs they could get to for kW-hrs was about eight cents, which isn’t bad. One of their concepts is a laser system that is very scalable (480 satellites for 1.2 GW). It uses a layered approach, with pump-laser diodes, microoptics, and a radiator on the back. Output beam is about a thousand nanometer wavelength. He thinks it the most promising architecture of those considered.
Now Paul Jaffe is reporting on a study on space-based power that was performed by the Navy Research Lab. In the beginning, they encountered a lot of skepticism within the lab. Their approach was to look at it in the context of providing Navy/Marine power needs. Study looked at military applications only. They supported the AFRL requirements workshop in July, and are working with NASA on the ISS demo.
They had three findings. First, the concepts are technically feasible, they seem relevant to military needs, and safe power beaming is restricted to large immobile sites. Wireless power transfer is necessary for SBSP, but it’s a research area in its own right. No consensus among experts as to best concept. Economics and political priorities will be important, but this wasn’t examined by NRL.
They also found that NRL has some key capabilities in many of the technologies (I’m shocked, shocked…).
The third was that different operational scenarios will require different technologies. Large-area applications can use microwave, but applications requiring higher power density will need lasers. Delivery of energy directly to individual end users, vehicles or small widely-scattered nodes isn’t currently practical.
They recommended continued NRL funding, but got the impression when they briefed the director that he still considers other energy areas more promising until more of the risk is retired.
A question from the audience brings up the point that DoE seems to be missing in action, considering that they’re supposed to be interesting in, you know…energy. There needs to be more of an outreach from other agencies to them to get them involved, particularly if DoE is supposed to be putting together new positions for an incoming administrations.
Another speaker from NRL, Michael Brown, follows with a talk on space structures issues. We have a long way to go from seventy meters (the current longest structure) to kilometeres in scale. Showing examples of ultralight space deployable beams.
Sorry, my eyes are glazing over (also a little sleepy after lunch). Structural analysis is not my bag. Showing concepts for trusses. Showing concepts for automated orbital assembly.
A break, a break, my kingdom for a break…
[Update after the break]
I’m not paying much attention to the current talk which is about wireless power in a deployed base in environment. The speaker said, perfectly deadpan (and he was probably quite serious), “we can’t introduce anything into a war environment that is unsafe.”
“Gentlemen, you can’t fight in here. This is the War Room.”
Jordin Kare (formerly of Livermore) is giving a talk on various space applications for lasers, some in space, some ground based with space relays. Optics are cheap, don’t generate much heat, don’t weigh much, none of which are the case for lasers, so keep lasers on the ground and put the optics in space.
Thinks that GEO is still the best place, for relay optics so that no tracking of moving satellites is necessary. Also less gravity gradient. But GEO implies big optics. He prefers diffractive optics, using thin sheets of materials with vacuum vapor deposition of metals to make a fresnel lens. It is insensitive to out-of-plane displacements, while mirrors are orders of magnitude more so. They can be lightweight, rolled up, folded. Shows a five-meter example made of panes of glass built at Livermore a few years ago. he thinks that a twenty-meter lens can fit on a Delta IV. Thinks that he could get by with six tons in GEO with relay system as opposed to thirty tons if the laser is place in orbit. Notes that NASA has looked at a similar system with a relay in L1 for powering a lunar surface base from the earth. Talking about using such systems to power electric propulsion vehicles, so they don’t have to carry the mass of their power supply, both for earth orbit and earth escape missions. Agrees with Jay Penn on approach of using laser modules, if you really want the lasers themselves in orbit.
[Friday morning update]
I’ve continue here.