Chair Force Engineer

Tuesday, April 21, 2009

Spiral Development: The Chair Force Engineer Plan for Closing the Gap and Enabling Human Lunar Exploration

Today's big news for Project Constellation comes in the form of Aerospace Corporation's independent study of using Heavy EELV's to launch the Orion spacecraft. The short of it: there are no problems with black zones, and the launchers can launch Orion with performance to spare. But the costs of doing so won't be trivial, and EELV+Orion won't be operational until 2014 or later. That's not much of an improvement over Ares I.

Right now NASA faces two challenges that are often opposed to each other. The first is fielding a human space launch capability in a minimal amount of time after the shuttle is retired. The second is the political consideration of retaining as many shuttle jobs as possible after the shuttle retires. Ares retains shuttle jobs, but it won't be ready for another six years or more. EELV and COTS-D might be able to shorten the post-shuttle gap, but they don't retain the shuttle workforce.

Since everybody seems to have their own ideas about how Project Constellation should run, I'd like to share mine. My ground rules are simple:
1) Get a manned spacecraft flying to ISS as soon as possible
2) Whenever possible, minimize development costs
3) Take a spiral approach to development, sacrificing the arbitraty 2020 moon landing date in favor of incremental and affordable advancements.

The first step would be halting all work on the Ares launch systems to evaluate which elements are applicable to the spiral development program that I propose, albeit on a longer time schedule than the current NASA plan. Once that's been accomplished, the Chair Force Engineer plan for manned spaceflight can begin in earnest.

1) Fully fund SpaceX's COTS-D effort
This is a no-brainer. Dragon is a simple capsule designed for one mission: deliver humans and cargo to ISS. It's the furthest system along the path that can shorten the gap.

2) Replace the current Space Shuttle system with a block I Shuttle C
Shuttle C shouldn't be hard to develop, as much of the work was completed prior to 1993. Even the leftover engines from the shuttle program can be expended on Shuttle C missions. While Shuttle C would be tasked with delivering cargo to ISS, we have to face reality: it's really there as an interim measure for retaining the shuttle workforce over the long haul while not endangering astronauts on further shuttle missions.

3) Make block upgrades to Shuttle C as the budget permits
The first order of the day is to find a replacement for the finite supply of space shuttle engines. RS-68 is a good canddiate, but it needs upgrades to even come close to SSME performance levels. The new injector plate and turbopumps from RS-68A&B are a good start, but a regeneratively-cooled nozzle would be really nice.

Shuttle C is also expandable in the SRB department. If NASA insists on paying ATK to develop longer SRB's than the current ones used byu the shuttle, they can be integrated with Shuttle C fairly easily.

4) Create a manned capsule capable of returning to earth from lunar trajectories
Perhaps Dragon could be upgraded for lunar missions. Certainly SpaceX has been discussing circumlunar Dragon missions, and I wouldn't rule out a "Block 2" variant with a beefier heat shield and enough consumables for a lunar mission. If Dragon Block 2 doesn't pan out, the Orion spacecraft could be revived using Falcon 9 Heavy or a Heavy EELV as a launcher.

5) Create an Altair lander and other elements of a lunar transit system, designed for launch on Shuttle C.
I'm agnostic on whether rendezvous in earth orbit is superior to rendezvous at an earth-moon Lagrange point. The important thing about my plan is that decisions such as EML vs. LEO are deferred until the budget exists to develop lunar-capable hardware. Certainly both would be possible using Shuttle C, in-space assembly, and on-orbit refueling. It's certain that a competent lunar mission could be staged using a capsule launched on a Heavy EELV, a lander and propulsion stage that are launched unfueled by a Shuttle C, and a load of propellant delivered by a second Shuttle C.

In closing, NASA has gotten itself into a lot of trouble by avoiding the "pay as you go" approach in favor of redoing Apollo on a shuttle-era budget. Unless the agency changes direction very soon, there will be a long gap and a brain drain in central Florida. The solution is the time-honored technique of spiral development. NASA should accelerate Dragon, fly an interim Shuttle C, and upgrade Shuttle C for sustainable operations before devloping lunar hardware in earnest. Such an approach gives policymakers enough options to ensure that the US stays in the manned spaceflight business even if the lunar goal is abandoned or replaced with more ambitious exploration targets.