Chair Force Engineer

Thursday, September 03, 2009

Orion Revisited

Let's assume for a minute that the post-Augustine national space policy emphasizes the commercial development of a human spacecraft to replace the space shuttle. Obviously SpaceX has the inside track with Dragon, which might be capable of manned flight by 2012. But where would this leave Orion in the grand scheme of things? It might continue at a reduced funding level as a backup to the commercial capsules, but some strategic decisions by Lockheed Martin (and perhaps Bigelow Aerospace) might put Orion back on track to thrive in the commercial space market.

Unlike it's intended Ares I booster, the Orion spacecraft is a generally sound idea. It's rooted in mature technologies and design concepts that would assure safe human return from the moon. (A biconic design might be better for returns from Mars, but there's a lot of controversy about which shape is best for the Mars return vehicle, and how far off that objective really is.)

Orion's problems up to this point have stemmed from NASA's shifting requirements. Until Ares I flies (if that happens at all,) the booster's performance (and Orion's mass budget) are uncertain. The original Orion specifications called for a maximum of six passengers, the ability to operate autonomously in lunar orbit, enough consumables to support four humans during a lunar round trip, and landings on terra firma. The new Orion specifications are for a four-passenger capsule that will likely maintain a pilot while in lunar orbit, and will land in the ocean at the mission's conclusion. Even the capsule's diameter changed, shrinking from 5.5 to 5.0 meters early in the design cycle.

Orion's mass budget always seemed optimistic in my view. The Apollo capsule, designed for a maximum crew of five and sized to a 3.9 meter diameter, weighed in around 30 tonnes in its lunar variant (although the earth-orbit missions loaded less propellant and consumables, weighing in under 15 tonnes.) The mass target for Orion was under 23 tonnes, even though it was sized for 5 meters diameter. Mass savings can be attributed to less propellant (Orion doesn't perform a lunar orbit insertion burn) and using solar panels instead of fuel cells.

Maybe these mass savings offset the added mass of the larger capsule when comparing Orion to Apollo. It's hard to say from my "Monday Morning Quarterback" chair. But it does seem safe, based off the Apollo experience, that a 5-passenger capsule with lunar-capable heat shield would weigh in just under 15 tonnes when configured for missions to the space station. Previous NASA estimates for comparable capsules, conducted during Mars design reference mission studies, came up with a mass under 10 tonnes. This lines up pretty well with SpaceX's estimates for the mass of a fully-loaded Dragon.

With all that being said, LockMart's work on Orion up to this point is far from a waste. If nothing else, LockMart should press on with its own money to get a commercial version of Orion flying (if the commercial capsule option comes to fruition.) Bigelow Aerospace has already proposed "Orion Lite" to launch on an EELV by 2013, but it's unclear if this idea has any official support from Lockheed Martin. And it's clear that for Orion to be commercially-competitive, it will need to fly in a "lite" version without all of the lunar frills.

A commercial Orion would need to keep its mass low, to fit on existing commercial launchers. Even if the capsule was scaled back to Apollo's 3.9 meter diameter, this may still be a tough order. After all, the "Zero Base Exercise" from the 2007 time frame cut Orion back to dangerously low redundancies in critical systems. Redundancy was only restored if extra performance squeezed out of Ares I freed up the mass budget to put it back in.

At the same time, a commercial variant of Orion would be free from NASA's fickle whims and requirements creep. There's no reason not to touch down on dry land. Soyuz has been doing it for over 40 years, thanks to six braking rockets in the capsule's heat shield. Orion could also move to two rows of seating and add more paying passengers (something currently banned under NASA's human-rating requirements, although it's featured in commercial capsule designs like Dragon.)

In short, commercializing Orion would give Lockheed Martin a head-start in the race for commercial orbital spaceflight and make for an interesting race between Orion and Dragon. But Orion would need to go on a massive diet, and the commercial Orion would be a very different beast compared to today's Orion designs. Ultimately it's in America's best interest to have at least two commercial capsules in operation, and it would be exciting to see Orion continue on in this fashion.