Back On The Air

Live, from the space solar power conference in sunny Lake Buena Vista, FL, under the ever-watchful eye of Mickey.

I have power, I have wireless, I’ve had my proteinless continental breakfast, which seems to be riguer at these aerospace conferences, and I’m ready to blog. Session overview will start in a few minutes.

[A few minutes later]

Omar Mendoza of the Air Force Research Lab (AFRL) is keynoting. He is head of a new energy and environment office. One of the things that they’re working is biofuel from algae, but they see space-based power as a potential breakthrough technology for meeting military power requirements in an environmentally friendly way. Purpose of this conference is to identify technology gaps that must be filled to make it a reality.

Anticipate that early next year the incumbent president will be asking what the military is doing in the way of energy, and they want to have a roadmap ready to present to the new CinC, whoever it is.

Lt. Colonel Ed Tovar of the Marine Corps Warfighting Lab now giving a history of the recent activities, including the space power studies performed last year by the National Space Security Office, and the interest that it seems to have aroused. Has gotten interest from environmental groups, energy companies, utilities, Congress, etc. Idea of tying energy to aerospace technology seems appealing. He tells people that this is something that justifies the exercise of due diligence to determine its potential. Talked about introducing John Mankins with a smart guy at NSSO, and had them get into a numbers battle over lift requirements, and that is the kind of activity that he wants to see continue. Two major thrusts: initiation/continuation of studies (much deeper and broader than NSSO report) and develop a roadmap for a demonstration strategy (space-space, LEO to ground, eventually from GEO). Terrestrial power beaming already happening as shown by the Hawaii test. Idea is to generate power in a permissive environment, and provide it in a “less permissive” environment. Wants to use structure and power available at ISS to do in-space demos, and has talked to people at NASA Ames and JSC about coming up with plans for a wireless power transmission demo at ISS.

Notes that Hawaii experiment didn’t just demonstrate technology, but they flew aircraft through the beam to characterize it, determine environmental effects, density, efficiency, etc. See it as a form of “soft power” that can help avert conflicts in the twenty-first century. He wants to make this technology a “comma” in the national debate, when energy companies and presidential candidates talk about energy options. “wind, solar, biofuels,…energy from space.”

Joe Howell of Marshall coming up next to talk about NASA’s technology roadmap.

Oops. Nope. Neil Huber of Concurrent Technology Corporation (CTC) is giving a summary presentation of military requirements, based on a workshop in July. They gathed power requirements for military units at various levels (person, squad, deployed unit, base, etc.), and determining that 3-5 MW is a prevailing military need. Purpose of this workshop is to come up with a rough roadmap.

They also have intangible requirements (strengthen intel, protect critical bases of ops, etc.) Of eight of these, six of them could be satisfied by power from space.

SSP could support the joint force attributes required by strategy if energy can be provided to the force at relevant levels. Could be a game-changing capability. It would be nice not to have to carry batteries, or deploy diesel generators and their fuel.

Space-centric beamed power could provide stability of operations (no concern about having a fuel convoy intercepted and disrupt ops). Nice to be able to quickly redeploy power from one area to another. Could have been very useful after Katrina or Ike, or after the tsunami.

Services had an official requirement to reduce fossil fuel use, and this could play into that. Many DoD bases dependent on fragile and vulnerable commercial power infrastructure–this could make them more independent and robust. 2005 Energy Policy Act mandates that DoD installations transition to green technologies. needs vary from 3kW for a person to 9 MW for a brigade (varies among services). Giving a few examples. Watts for a soldier with his equipment, with heavy batteries, ranging up to 80 MW dedicated to propulsion for a destroyer. ONR testing 35 MW superconducting electric motor.

Air Force has more a better understanding of their requirements, but can’t really keep up with the slides (this will be available later, probably on line). Notes that Marines have a very high AA battery requirement. Bottom line: could reduce deployment footprint and logistic footprint (reduced fuel convoying, which is also a dangerous activity). Could provide more stable, enhanced operations at all levels. 3-5 MW seems to be near-term critical number.

In Q&A, Colonel Paul Damphousse is relating experience from Iraq, where it was more dangerous to be on the road than in the air, and pointed out how nice it would have been to put down spot beams in remote areas rather than convoy fuel. In response to a question, Huber notes that fuel in the field can cost anywhere from $50 to $200 per gallon, after shipping it to the front (particularly by air). Makes this a much more attractive market for a high-cost (at least technology) like this.

OK, now Joe Howell is speaking about the NASA technology roadmap. His talk is based on work done in the last ten years (mostly from 1998-2002). Showing slide of classic reference SPS/Rectenna system from the 1970s DoE/NASA studies. Required huge launch capacity. Showing very complicated chart of complexity of all the factors that go into whether or not SPS makes sense. Topic seems to come up every fifteen years or so. Now showing potential requirement to get CO2 reduced–need 40 TW of carbon-neutral power generation to reduce and stabilize at twice pre-industrial levels. When “peak fossil fuels” will occur remains without consensus–how much energy R&D needed for insurance policy?

Now getting back to more recent studies. Still have rectenna farms and large structures in orbit, but much more thin-film concentrators, lighter structures. Showing X33/VentureStar as transportation paradigm of the era. Also showing hypersonic vehicles, two-stage reusables, smaller systems with high launch rates. Studies were based on $200/kg launch costs. Still couldn’t close business model at that cost. Showing modular solar-electric concept to transport large space systems to GEO.

He has an eye chart of the technology areas that have to be advanced. Next chart focuses on state of near-term PV technologies–stretched-lens array, thin films, etc. Also showing solar concentrators that have actually flown in space (Deep Space 1). Need a much higher pointing accuracy for these types of systems, which makes the rest of the system more of a technical challenge.

Getting into microwave beam safety issues now (earlier had related the honeybee studies performed back in the seventies and eighties). Has the classic power density chart that shows it’s not a problem, but people still don’t believe it (just like the people who won’t live near power lines). Showing roadmap of demos laid out to 2021, but funding dried up about 2003. Has a chart showing growth of spacecraft power requirements over last quarter century–steady increase up to tens of kilowatts. Needs doubling every five and a half years. Describing solar panel architecture trades.

Overall, this strikes me primarily as not a coherent story, or one put together for this meeting–just a lot of pre-existing charts with historical results from various periods. Probably useful for people unfamiliar with the field, though.

Future needs–sandwiched options, collect on the front, beam out the back, 50%+ conversion efficiency. 5 km transmitter 80%+ efficiency, ten GW system, installed cost $2/watt. Need self-assembly, higher strength/weight materials, higher-temp solid-state devices, need to look at lasers as well as microwaves, but as always, need much lower transportation costs.

In other words, nothing new.

Question: how do we map the NASA quick-look study to the military requirements we just heard? 3 MW isn’t really practical for microwave systems because they don’t work for the wavelength. SPS size wasn’t drive by power requirements so much as aperture size. Wouldn’t lasers be better, given recent advances in solid-state devices? Howell notes that a LEO demo could be scaled down considerably for microwaves, and that lasers have issues with clouds, etc. Trades still need to be done. He notes that all of the work presented was to address the need for baseload power, and hadn’t considered these new military requirements. Bruce Pittman of Ames asking about potential applications for lunar bases. Could they beam from L1 to the lunar surface? Howell notes that Seth Potter (Boeing) will be talking about this later in the meeting. Competition for going into shadowed craters is nuclear. Jay Penn of Aerospace notes that he’ll be going into the economics this afternoon, in response to Bruce’s question about how close to closure they came.

Taking a ten-minute break now.

[A few minutes later]

Ron Clark of Lockheed Martin giving a talk now titled “Space-based Solar Power Gap Analysis–Solar Dynamic and Hybrid Launch Approach.”

Key to SBPS: increase revenues and lower costs (duh…)

Has an alternate solution motivated by premium-priced power applications such as shale extraction, remote locations and forward basing. Whenever senior people are briefed, we can show progress, but they still say “it’s still too tough,” based on the technology gaps. Have to come up with compelling plan that closes gaps and changes perceptions. Have to raise revenue above the grid (need $0.20/kW-hr). Need launch costs of $500/kg, and need to reduce spacecraft manufacturing costs to $1000/kg.

Identified apps where current technology may be good enough: peak power, industrial power and forward deployment/nationbuilding.

Notes that emphasis to date has been on photovoltaic (I would note that Brayton cycles were considered in the seventies, but they weren’t the reference baseline). He thinks it’s time to take another look at solar dynamic. Thinks that cost of space hardware is coming down not only due to technology advance (mass/function drops by factor of two every eight years, which translates to reduced costs), but also from economies of scale, which would apply to a system like this. Iridium experience shows that cost can come down a lot, particularly when one works closely with suppliers and reduces supply chain friction. Cost/kg can drop from $100,000/kg for one-off, and a hundredth of that for thousands. Sees launch costs as coming down as well with growing use of reusability.

He’s positing a “hybrid” launch system with reusable suborbital first and second stage, that meets with a medium earth orbit (MEO) electrodynamic tether as a skyhook. Reduces ETO delta V to 5.5 km/s. Identifying specific technology gaps associated with these systems. Looking at on-orbit assembly gaps. Not competitive with coal-fired power plants at current technology maturity level. Need system-level demos of specific technologies that would support SSPS assembly.

A lot of work has been done with a Closed Brayton Cycle (for topping, with Rankine for bottoming) that can have 50% net power conversion efficiency. Gaps here consist of long life, weightless operation, radiators, large inflatable collectors, and space-rated alternators. Thermal radiators are a particularly immature technology for this high-temperature application.

Also need efficient DC-RF conversion. Some new solid-state devices may offer very high (~90%?) efficiency. Need to consider orbits other than GEO. Trade and location will be driven by mission need. MEO might be the right answer for some applications. he sees highest technical risk in MEO tether and payload transfer, and on-orbit assembly cost reduction. Thinks that all risks are tractable, w

In questions, Keith Henson notes that shipping assembled satellites to GEO would be pretty hard on them, due to radiation and debris.

Now Mack Henderson from JSC (who I sat across from at dinner last night) is presenting a concept for a space-based solar power demo at ISS. Goal is to use existing hardware to do a demo in 2010. Have been coordinating with a number of organizations, at DoD (NSSO, AF Security Forces, AFRL, Army Research, NRL), DoE, academia, industry (Raytheon, L’Garde, Boeing,LMSSC/MDR/PWR and SAIC) and help from Futron. Still looking for a DoE liaison–they seem to be focused on terrestrial.

Goal is to provide measurable power from space to ground, have it safe, and show that it is scalable, within the budget and schedule. They want to validate efficiencies over several types of paths. Raytheon is working on a system with 6 K-Band traveling wave tube amps. They’re expecting to receive power on the ground on the order of 20 milliwatts from 600 watts transmitted, using Goldstone for the receiver, though other options are being considered. Each beaming experiment will last about ten minutes with about a hundred seconds of maximum power. They’re foreseeing a 27-month program for about $55M, hoping for a May 2010 demo.

Already a letter of intent from Gary Payton and Bill Gerstenmaier–NASA will do space segment, DoD will do ground, and help with money. Also provide TWTs, use of AFRL facilities and Tyndall, and help with roadmap. NASA fives a Shuttle ride, berth on ISS, money, use of DSN dish at Goldstone, and project engineering, with support from Raytheon and Texas A&M.

Benefits of concept are near-term launch capability, services available at ISS including humans present. Compared to doing a separate satellite on an EELV–would save hundeds of millions. Biggest risk is schedule. Asking for authority to proceed from NASA HQ next week.

Jay Penn is concerned about the low transmission efficiency of the proposed experiment, and suggests a laser for much better power transfer. It really is amazing that you can only get 20 milliwatts from 600 watts using that monster dish at Goldstone. It just shows how important aperture size is at that microwave frequency (2.45 MHz). It is being pointed out that there are already demos of low-power microwave power beaming from space–it’s called comsats. It’s determined to take this discussion off line.

Question: what will we learn from this demo and how will it help future designs and concepts? The answer wasn’t clear.

Colonel Damphousse points out that there is DoD support for this, and he appreciates the comments. We shouldn’t be focused on how many milliwatts or microwatts are being transmitted–beam characterization is important to allow us to scale up later demos. It has to be looked at as a first step, because we aren’t going to get billions for a 10 MW demo right now.

Bruce Thieman of AFRL is talking now about spacelift costs, and the implications for space solar power. Currently at $4000/lb to LEO, are only going to get to $400/lb with what’s currently funded. Current costs are high, vehicles are unreliable, with long call up. Goal is much faster turn around, much higher reliability and lower costs. Everything is currently horrendously expensive (a lot of dispute about his chart that has Shuttle costs at $450M–it’s got to be closer to a billion per flight these days). Showing commercial launch systems–SpaceX, ULA, AirLaunch, Microcosm and others, including Kistler–old chart). Even COTS vehicles can’t get costs below $1500/lb or so (Taurus 2 calculated to be $2000). EELV is in the $3400-4300 range.

Showing chart that says that reusable lower stage expendable upper stage hits a near-term sweet spot in cutting costs by about half. Still $300-$400/lb. Can’t do better until fully reusable, and that needs launch rates of forty or more a year. The reusable first stage is designed for a 48-hour turnaround. Long-term goal for fully reuable systems is four hours. Want to eventually see a thousand flights per airframe.

Talking about suborbital now. Most important thing that they will do is drive up launch rate and learn about operations, and high turnaround rate. They are a very important community. Showing classic chart of that shows energy costs to orbit–translates into a ticket price to orbit of $76 (about 38 cents a pound). Question is how to bring launch rate up. If we can bring satellites down to $300/pound to build, we could build more and launch them more often, and refresh technology more often as opposed to GPS, which is a fifteen-year satellite, mostly driven by launch costs. Have to change the culture of the satellite community, which will require initial drops in launch costs.

Now Richard Fork (UA, Huntsville) is giving a paper called “Adaptive Network for Power and Information in Near-Earth Space.”

His challenge was to come up with a way to use lasers for power, but not a weapon. Proposes a “quantum secure” laser-based network to support both power and information transfer from space. Looking into laser-based power and “intelligent cyber-secure adaptive networks.” Have to figure out a way to keep people from “hacking” the lasers. Sees it as an enabler for space solar power.

OK, so he’s talking about direct solar-laser conversion, and using lasers for launch (ablative). I don’t see how it relates to his summary of the talk, though. Has a chart of bullet points, not particularly related to each other, including one on asteroid deflection with lasers, the last one of which is “Main need is for a well managed program.

All is lost.

Time for lunch.

[Update a couple minutes later]

OK, not quite. Now he’s talking about quantum secure links again. Conclusions: need for both microwaves and lasers. Lasers alone offer highly directionsl efficent long-range power delivery. They alone offer a “quantum-secure” info network. And intelligent quantum secure power network can be designed an implemented within time frames of interest.

OK. Whatever.

[Update after lunch]

I’ve started a new post for the afternoon session.

One thought on “Back On The Air”

  1. “Also showing hypersonic vehicles, two-stage reusables, smaller systems with high launch rates. Studies were based on $200/kg launch costs. Still couldn’t close business model at that cost.”

    I participated on some of those studies when I was a grad student at Georgia Tech. I went into them a strong believer in SSP, but have been convinced that further research in the technology is fruitless ever since. The fact that there is no scaling effect in the rectenna for power level (given a fixed distance, transmission frequence, and transmitter aperture) is another huge cause of concern for a 3-5 MWe system. Read this entry for further understanding of this key (intractable) problem:

    Entropy Production: Solar Power Satellite

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