One paper refines the design of the Girasol 1 GW converter satellite, and re-defines the Mirasol. We brought the Mirasol down to near the orbits of the Girasols, to minimize the need for large capture area on the Girasol, taking into account the divergence of sunlight (a large divergence!!). Thus the Mirasols are now quite low, and hence will be in shadow (night) some of the time. This increases the number of Mirasols needed to keep all the Girasol converters supplied 24 hours a day. The radiators of the active thermal control system on the Girasol have also been re-examined. A combination of graphene sheets and other materials brings down the mass of the active thermal control system considerably.

2. The other peer-reviewed paper at the Big Sky conference refines the overall SPG architecture based on these newer numbers and reduced uncertainty, and updates the list of assumptions.The specific power of the entire system is still well up there around 1.6 kW/kg. Thus the Net Present Value calculations presented at the 2012 meeting become even more conservative, with reduced uncertainty in the ability to achieve the required parameter values.

Copies of the papers and presentations will be available after the meeting which is in the first week of March 2012. (Brrrrrr!!!!)

3. Our team is preparing a video summary of the project. We are working with a team guided by Professor Flournoy at the Ohio University.

4. Over the past year two peer-reviewed papers appeared in journals of the electonics world, trying to build interest in developing efficient, high power millimeter wave converters by pointing out the state of those technologies and the opportunities when power beaming becomes a routine affair. See the papers in the Journal of Low Power Electronics and the ACM Journal of Emerging Technologies. These were expanded from papers presented at peer-reviewed IEEE conferences.

5. Our initial paper on the 5-nation collaborative project to jump-start the Space Power Grid, appeared in the Journal of Space Communications and can be seen here:

Brendan Dessanti, Narayanan Komerath, Don Flournoy, "Visualizing Wireless Transfer of Power: Proposal for a Five-Nation Demonstration by 2020". Journal of Space Communications, Fall 2012. http://spacejournal.ohio.edu/issue17/fivenation.html

We are now trying to refine the design of those experiments and start the long process of getting the right people to talk to each other and think how to make it happen in detail (hint: Anyone at NASA, JAXA, ISRO, any Space Agency who will help us negotiate those mazes of standards and regulations and protocols, please???) Contact komerath at gatech dot edu Thanks!

OK, So how realistic is any of this?

Ours is the first architecture that goes all the way from inception to full-scale global Space Solar Power and defined realistic parameters for economically viable development. In other words, we do not stop at "the first demonstration after which private industry will rush to pick up the project" nor is the objective limited to "flags footprints and ticker tape parades". We aim to replace terrestrial fossil-based power generation with Space Solar Power. We do not project that Space Solar Power will be "too cheap to meter" or anything of the sort. In fact it may not become cheaper than today's fossil or nuclear-based power for a long time to come, but it will get there eventually.

We project that the Specific Power can be taken to over 1.6 kW per kg in orbit, compared to the levels of below 0.2 kW per kg projected for older GEO-based, low-GHz microwave beaming, Photovoltaic conversion architectures. The outstanding obstacles are given below:

1) Millimeter Wave conversion to and from 220GHz remains to be proven at high efficiency and high specific power. This is an area of rapid R&D progress so there is every reason to be optimistic. Demonstration experiments are needed in this area.

2) Efficient transmission through the dense, moist lower atmosphere can be done using waveguides tethering aerostats, which contain the transmitter/ receiver antennae. There is no breakthrough required here, just some imagination in applying aerostat and waveguide technology to this problem.

3) Eventually, the scale-up to 4 Terawatts requires 4000 1-GW satellite pairs, at a specific power of about 1.6 kW per kg - you can do the numbers to calculate the mass that must be put up. To do this within a couple of decades, runway-launched, air-breathing routine space access is required with year-round, regular launch and landing operations at the rate of about 1 per day from numerous locations around the world. This is in fact the harder problem, but any move to a serious Space economy will require this.

Some people tell us that our efforts are "academic" because we base them on technologies that are rapidly developing, rather than calling for a rush to a short-term public-funded (hugely expensive!) "demonstration". But our counter to that is that if the architecture does not make sense from simple laws of physics and simple commonsense, it is not going to make sense to national lawmakers who have excellent staffers, and certainly not to the taxpaying public.

We base our hopesand our architecture calculations on hard numbers and careful examination of technology, not on wild hopes of a sudden collapse in the cost of space launch, or sudden infusions of hundreds of trillions of tax dollars into architectures that are clearly not realistic as seen from simple technical considerations such as the antenna sizing equation.

There is no great hurry to launch the first full-scale demonstrator: it is still at least 15 years away. We can focus our efforts on getting the technology right and the business plan viable, before asking the taxpayer to fund the Gigawatt-level space stations.