BEING THERE: An asteroid, Mars's moon Phobos and the Red Planet's surface are all on the proposed itinerary. The moons are exaggerated in this artist's fanciful conception. Image: Illustration by Patrick Leger
- Space policy in the U.S. has gone through an upheaval. NASA has retired the shuttle, given up the Constellation program that was to have replaced it and outsourced orbital launches. It is supposed to return to what it does best—going where no one has gone before. But how?
- The authors argue that engineers need to assume that the political process will continue to be unpredictable—and plan for it. They must design mission options that can be ramped up or down as circumstances change.
- Deep-space vehicles propelled by ion drives can mount progressively more complicated expeditions to lunar orbit, near-Earth asteroids and eventually Mars.
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In October 2009 a small group of robotic space exploration geeks decided to venture out of our comfort zone and began brainstorming different approaches to flying people into space. We were spurred into action when the Augustine commission, a blue-ribbon panel that President Barack Obama set up earlier that year to review the space shuttle and its intended successor, reported that “the U.S. human spaceflight program appears to be on an unsustainable trajectory.” Having worked in an exciting robotic exploration program that has extended humanity’s reach from Mercury to the edge of the solar system, we wondered whether we might find technical solutions for some of NASA’s political and budgetary challenges.
Ideas abounded: using ion engines to ferry up the components of a moon base; beaming power to robotic rovers on the Martian moon Phobos; attaching high-power Hall effect thrusters to the International Space Station (ISS) and putting it on a Mars cycler orbit; preplacing chemical rocket boosters along an interplanetary trajectory in advance so astronauts could pick them up along the way; using exploration pods like those in 2001: A Space Odyssey rather than space suits; instead of sending astronauts to an asteroid, bringing a (very small) asteroid to astronauts at the space station. When we crunched the numbers, we found that electric propulsion—via an ion drive or related technologies—could dramatically reduce the launch mass required for human missions to asteroids and Mars.
It was like being back in the NASA of the 1960s, minus the cigarette smoke. We talked about what we can do and avoided getting mired in what we cannot. After our initial analysis, we put together a lunchtime seminar for our colleagues at the NASA Jet Propulsion Laboratory (JPL) that synthesized these notions and calculations. Throughout the following spring and summer we met other engineers and scientists who were interested in our approach and gave us ideas to make it better. We learned about experiments that people inside and outside NASA had been conducting: from tests of powerful electric thrusters to designs for lightweight, high-efficiency solar arrays. Our discussions have grown and become part of a larger groundswell of inventive thinking across the space agency and aerospace industry.
We have now combined the most promising proposals with tried-and-true strategies to develop a plan to send astronauts to the near-Earth asteroid 2008 EV5 as soon as 2024 as preparation for an eventual Mars landing. This approach is designed to fit within NASA’s current budget and, crucially, breaks the overall task into a series of incremental milestones, giving the agency flexibility to speed up or slow down depending on funding. In a nutshell, the aim is to apply lessons from the robotic scientific exploration program to renew the human exploration one.
Small Steps Make a Giant Leap
The Augustine commission’s report ignited a mighty political fight, culminating in the decision to delegate much of the task of launching astronauts into orbit to private companies [see “Jump-Starting the Orbital Economy,” by David H. Freedman; Scientific American, December 2010]. NASA can now focus on transformative technology and push human exploration on to new frontiers. But how can the agency move forward without the political support and resources it enjoyed during the glory days of the Apollo moon landings?
The established approach in robotic exploration is incremental: develop a technology portfolio that enables increasingly ambitious missions to take place. Rather than relying on an all-or-nothing development path to a single target, the robotic exploration program makes use of novel combinations of technology to reach a variety of targets. To be sure, the robotic program has suffered its own mistakes and inefficiencies; nothing is perfect. At least it does not grind to a halt when the political winds change or when technological innovation lags. The human program can borrow from this strategy. It need not commence with “one giant leap” as with Apollo. It can embark on a series of modest steps, each building on the one before.