NASA's Asteroid Redirect Mission (ARM) is not getting much love, according to Eric Berger, writing in the Houston Chronicle. NASA can’t afford to send humans to Mars. “With its current plans to build a large rocket, the Space Launch System, NASA can’t even afford to go back to the moon,” he writes. “What NASA can afford to do, in about a decade, is bring a small asteroid to a location near the moon, and then send astronauts to fly in formation with the rock.”
Berger quotes John Culberson, a Houston Republican, as saying, “I don’t think there’s a clear consensus on a lot of things in Congress, but we all agree that pushing a rock around in space is a waste of taxpayer dollars that we don’t have to spare.”. (Read Berger's full post here.)
But NASA has offered several benefits (which I'll quote in part in the bulleted list below) of ARM in particular and operating in the cis-lunar space in general:
- Solar electric propulsion. Using advanced Solar Electric Propulsion (SEP) technologies is an important part of future missions to send larger payloads into deep space and to the Mars system. Unlike chemical propulsion, which uses combustion and a nozzle to generate thrust, solar electric propulsion uses electricity from solar arrays to create electromagnetic fields to accelerate and expel charged atoms (ions) to create a very low thrust with a very efficient use of propellant. When compared to conventional chemical propellant sources, the ARM mission uses five to 10 times less propellant as a result of the SEP technology.
- Trajectory and navigation. As we learn to maneuver a large mass like an asteroid using low-thrust propulsion and the gravity fields of Earth and the moon, we’ll prove valuable technologies for the future Mars missions. Human missions to Mars will require far more cargo at a long distance from Earth—much greater than the amount of cargo we currently send to the space station, which takes about one to three days to arrive. The ARM mission will help perfect techniques for sending those large masses to Mars by requiring a precise set of maneuvers to intercept the asteroid at a distance with large time delays.
- Advances in spacesuits. Some of the spacesuit systems NASA uses today aboard the International Space Station were first designed 40 years ago and require regular cargo resupplies from Earth. These spacesuits, known as EMUs (Extravehicular Mobility Units), are truly engineering masterpieces—but they were not designed to be easily maintained by the crew, and are typically returned to Earth. Spacesuits designed to operate in deep space and for the Mars surface will require upgrades to the primary life support system (PLSS). For example on Mars, a carbon dioxide atmosphere exists rendering the current PLSS’s cooling technology obsolete.
- Sample collection and containment techniques. Asteroids are the left over building blocks of the solar system—pristine pieces of the matter that formed our sun’s planets and their moons. Astronauts aboard the Orion spacecraft will take samples of the redirected asteroid and bring them back to Earth for scientific evaluation and study. Additionally, the interaction with the asteroid could provide data on the internal structure of the asteroid and the answer many long-debated questions about their composition. Some asteroids may contain resources future astronauts could use to extract water and breathable air, create rocket fuel, or even use for 3-D printing.
- Rendezvous and docking capabilities. Future human missions to Mars will require new capabilities to rendezvous and dock spacecraft in deep space. We will advance the current system we’ve developed with international partners aboard the International Space Station—the International Docking System. A mission to Mars could require us to stage several vehicles in cis-lunar space first, like habitats or cargo modules. Astronauts could then dock with these vehicles before starting their journey to Mars. Astronauts landing on Mars will also need to re-dock with their Orion spacecraft for the return trip home.
- Developing the building blocks for exploration. Overall, the Asteroid Redirect Mission combines the best of NASA's technology and human exploration efforts. ARM is a compelling early use of the Orion spacecraft and SLS rocket that also affordably lays more foundation for future missions to Mars. The mission will lower the costs of exploration by building systems that can be used and upgraded multiple times. Ultimately, the mission allows NASA to move as fast as possible on a human path to Mars, while minimizing new developments, building experiences aboard the space station, and testing new systems and capabilities in the proving ground of cis-lunar space.
I have not seen critics rebut these points effectively.