Chair Force Engineer

Friday, March 02, 2007

TeamVision (Part 4 of 5)

Perhaps I was a bit premature in condemning TeamVision during Era 3 of their plan for lunar and Mars exploration. I criticized them for relying on direct landing and ascent on the moon instead of an EML1 rendezvous. By the time I got into their Era 4, creation of a lunar infrastructure, they turn into voiciferous advocates of an L1 infrastructure.

The thrust of TeamVision's Era 4 is that the moon will be utilized to produce liquid oxygen. This propellant is delivered to a transportation node at the Earth-Moon Lagrange point. Orion CSM's will be launched on Jupiter rockets to dock with the EML1 propellant depot. The astronauts will transfer to reusable, Mars-class landers that are fueled by lunar liquid oxygen. Further, the EML1 depot will serve as an assembly point of a future Mars spacecraft, assembled out of modified Orion CSM's, already-developed habitat modules, and 10m rocket stages developed for the Jupiter II.

The report really doesn't address how the reusable landers will be refueled with methane, but this will presumably be delivered to the EML1 depot from earth. The station will also need to be refueled with propellants to maintain its station at EML1 from time-to-time. All of this requires a lot of mass to be boosted from earth. Era 4 relies on yet another new rocket, the Jupiter III, to deliver between 200 and 500 mT of cargo to low earth orbit.

While Jupiter III is the lynchpin of TeamVision's Era 4 architecture, I feel that it's too complex to proceed in its present form. The rocket's core is based on the shuttle ET, with J-2X engines mounted underneath. This core is flanked by two standard shuttle ET's, each one with two standard shuttle SRB's. What engines do these ET's feed? Why, there's a cluster of "RS-100" engines (apparently a scaled-up RS-68) mounted underneath the J-2X's in an expendable pod! The rocket apparently begins its ascent by igniting the RS-100's with propellants in the two laterally-mounted ET's. Then the SRB's ignite and the rocket lifts off. The SRB's are the first to burn out and are cast off. Then the ET's are depleted, so they are cast off, along with the RS-100 pod. Then the J-2X's ignite on the core. Once the core burns out, an upper stage with two J-2X engines ignites to push the payload into orbit.

Jupiter III seems like a horrendously complex way of launching what would otherwise be a very wise goal, the buildup of an L1 transit node. There's a lot of complex plumbing connecting the two ET's to the engine pod, and the thrust from the four SRB's, mounted far off the vehicle's centerline, has to be carefully balanced. My preferred concept would use a two-stage, 10m core which burned oxygen and hydrogen propellants. The first stage would be flanked by several kerosene-fueled booster modules. The number of kerosene boosters would be varied based on the mission requirements.

Overall, what's my opinion of the Era 4 plan? It's mixed. The L1 infrastructure is genius, even if it's used for the moon only (not as a starting point for a Mars mission.) Jupiter III looks more like mad science than genius.