Main Engine Cut Off

Marcia Smith of SpacePolicyOnline.com published an incredibly detailed history of NASA’s asteroid mission, and talks about where it stands today. The cost of the mission is growing, and will seemingly exceed the cap set previously. That leaves NASA in a tricky spot and they need to decide how to play their hand—ask for more money, or scrap their current plans (for a third time) and figure out what fits in the budget.

NASA calls it the Asteroid Redirect Mission (ARM), which made sense when their plan was to redirect an entire asteroid into lunar orbit. Instead, they plan to snag a boulder off the surface of an asteroid and bring that back to lunar orbit.

By their definition, a Mars sample return mission that included a rendezvous in Earth orbit to retrieve the samples could be called the Mars Redirect Mission. Hell, the Apollo program could have been the Moon Redirect Mission.

Propagandistic name aside, turning it into a boulder retrieval mission eliminated what I thought was the most important aspect of the mission: planetary defense. Learning how to move asteroids is an incredibly important skill for a spacefaring civilization. However, the planetary defense angle was continually downplayed as not a main focus of the mission, probably because planetary defense could also be seen as planetary offense—if you can move an asteroid out of the way, you could also move it into the way.

Without practicing planetary defense, ARM is left with two main goals: to demonstrate solar electric propulsion in use with heavy cargo, and to manufacture a destination for a mid-to-late 2020s SLS/Orion mission.

NASA has declared solar electric propulsion for cargo an absolutely necessary component of the path to Mars. I disagree, but if NASA wants their roadmap to include a solar electric propulsion cargo demonstration, I’d much prefer the kind directly applicable to the end goal:

If NASA wants to put ARM on the critical path to Mars, it should be focused on Mars.

The second goal of ARM—to provide a destination for a mid-to-late 2020s SLS/Orion mission—is even more of a disappointment. The SLS and Orion programs have set NASA up to be flying consistently(ish) in the 2020s, but with nowhere to go and no payloads to test, since nearly all of the budget has been spent on the launch vehicle and spacecraft.

Without landers, ISRU units, or other critical components, NASA wouldn’t be quite ready to head to Mars by the late 2020s. ARM is an admission that those components won’t be ready to be tested by even the late 2020s, or else there would be no need to manufacture a destination for those flights. There would be plenty of work to be done, none of which involve a ridiculously expensive sample return mission.

Instead, the mission needs to fly somewhere, so including it as part of ARM lets each flight (robotic and crew) provide a rationale for the existence of the other. Hardly inspiring.

The only hope I have is for commercially-built habitats to be placed in lunar orbit, and for the mid-to-late 2020s missions to be based there. If NASA isn’t spending budget on landers or ISRU units, they should at least spend it on long-duration habitats.

The Asteroid Redirect Mission is something that I think should be flown in its fullest state—that is, actually redirecting an entire asteroid. Planetary defense is an important skill that we haven’t yet acquired. The importance and seriousness of the asteroid program should warrant its own program, and not be forced onto the critical path to Mars.

The mere existence of ARM on NASA’s #JourneyToMars roadmap is an admission of just how flawed that roadmap is in its current state.