Wednesday, March 31, 2010

Flexible Path to the Moon and the 2011 NASA Budget: Adjusting the Heavy Lift and Propulsion Technology Budget

We have already seen several examples of how the 2011 NASA budget can be adjusted to support the Flexible Path to the Moon by emphasizing near-term space destinations like lunar orbit and Earth-Moon Lagrange points (the same early destinations that start the Augustine Flexible Path to Mars) as well as longer-term destinations on the lunar surface. We simply focus most of our efforts on the reachable destinations along this path rather than difficult destinations like the Martian surface. The 2011 NASA budget for Heavy Lift and Propulsion is no exception.

Early Flexible Path to the Moon destinations don't need heavy lift, and if we can lower launch costs through something closer to mass production of launchers, and at the same time we can demonstrate technologies like autonomous rendezvous and docking, propellant depots, in-space assembly, ISRU, reusable space-only vehicles, and/or reusable lunar landers, we won't need heavy lift for the lunar surface, either. We shouldn't expect success with all of these technologies, but success with a few should be good enough. Leveraging commercial and international participation should also help us develop affordable and sustainable lunar surface access and development without having to develop an unaffordable heavy lift vehicle like Ares V or its close relatives.

It may make sense to advance some sort of heavy lift capability to add to our bag of tricks, but only if it can be done in a way that is both useful and affordable. We don't need heavy lift, but we can surely benefit from useful and affordable heavy lift. Fortunately, the 2011 NASA budget already takes a useful and affordable approach. It develops an RD-180 class engine made in the U.S. that can be used on a future heavy lift vehicle. Such an engine doesn't require a heavy lift vehicle for its justification; it can be used in other rockets (the Atlas V uses the Russian RD-180). Thus, the budget's heavy lift development approach is inherently useful beyond the HLV. The budget's approach also appears to be affordable, leveraging the existing EELV infrastructure and expertise that will exist and need to be paid for whether or not NASA explores or develops an HLV.

The Flexible Path to the Moon would benefit from propulsion capabilities like the following:
  • reusable propulsion for astronaut vehicles to go back and forth between LEO and beyond-LEO cislunar space destinations
  • highly efficient (and possibly reusable) propulsion to get cargo from LEO to beyond-LEO cislunar space destinations
  • propulsion for (possibly reusable) vehicles to get cargo and/or astronauts to and from the lunar surface

If the Flexible Path to the Moon is taken, propulsion research and demonstrations should concentrate on these crucial areas as a higher priority over propulsion to shorten long deep space missions or propulsion for heavy lift.


mp_meijering said...

Why even spend money on a new RD-180 class engine when there is already an RD-180? Is there reason to assume ULA would want to use such an engine for Atlas? It seems likely a US engine would be more expensive than a Russian one, given US wage levels. And even if they would want to, why shouldn't they invest in it themselves?

A US kerolox engine wouldn't be harmful, but it is a luxury we don't need.

Concerning reusable propulsion: this is very important, but if you use L1/L2 as an additional staging point it can be done with present technology.

Anonymous said...

mp_meijeing: I've also seen estimates for a U.S. RD-180 equivalent that are considerably more expensive than the one that exists.

From the point of view of the government, a big part of the rationale is the aerospace industrial base and workforce. For example, see

Having U.S. supply for national security applications is another rationale from the government side. That strikes me as being a more credible concern than the use of Soyuz, for example.

On the ULA side, I don't see why they'd make the investment, for exactly the reasons you mentioned.

On costs, the 2011 NASA budget does have the goal of reducing costs for the engine (as well as other improvements). From the budget:

"Other key target characteristics for this new capability include improvements in overall engine robustness and efficiency, health monitoring, affordability, and operability. In every aspect of the design, NASA will seek to incorporate features that will reduce manufacturing and operating costs for this engine, once it achieves nominal production status."

Time will tell how that works out.

I have to say that, from the point of view of NASA exploration, I'd put this and the other HLV work at a lower priority than the other propulsion work.


Tom the Younger said...

I can see where SpaceX would really like a single large kero-lox engine to replace the 9 that are currently on it's Falcon 9. Another large rocket motor would be very useful if only for redundancy. 2 really is better than 1 in such matters.