Sunday, June 24, 2012

Walking Eagle Nomination for the Ad Astra Rocket company

Dear Dr David Livingston and the Space Cynics,

I would like to submit a Walking Eagle Award nomination for the Ad Astra Rocket company for their "Human Transportation to Mars" concept.

The primary basis of my nomination is the size of the nuclear reactor proposed, but even if such a reactor and all the other support infrastructure to launch the mission from an Earth-Moon Lagrange point was available, and their propulsion technology actually worked, I think there is a very strong argument that such a fast transit decreases mission safety because it eliminates the free-return-trajectory abort mode.

The only nuclear reactor the US has ever flown in space is the SNAP-10A, which produced a mere 650 watts of electrical power, from 45 kW of heat. The SP-100 reactor program, which were never flown, was to produce 100 kW of electrical power from 2 MW of heat. The Russians flew reactors which produced 3 kW to 5 kW of electrical power, and built some 40 kW reactors that were never flown. So when Ad Astra baselines a 200 MW nuclear reactor, they're talking about a reactor 40,000 times as big as anything that has ever flown! It's even 2000 times as big as anything anyone has ever tried to build, and 5,000 times as big as anything that has ever been actually built!

There are other arguments against a nuclear reactor of this size, relating to the power per kg and the size of the radiators that would be required, however as it is obvious that no such reactor will be available, they are superfluous.

Need I say more?

Okay I will. Come with me now as we enter the fantasy land where electrical power for the VASIMR thruster is free and plentiful. Perhaps we have a nuclear fusion reactor that works in space and doesn't require any heat radiators, etc. Also, we have superconducting magnets that work at space temperatures, and all this technology is ready. Also, there's scientifically literate politicians both in the White House and the Congress and the US has paid off their national debt with the profits they received from selling ponies to North Korea.

As pointed out by Bob Zubrin last year, hurtling towards Mars at breakneck speed means you better be successful at stopping or your crew goes cruising off into the outer solar system never to be heard from again. In a six month transit, which has already been achieved using modest chemical propulsion, the crew has the option of aborting back to an Earth returning trajectory. How is throwing away this abort mode in the name of making the trip safer a good idea?

Also, their rocket doesn't actually produce any thrust.