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Setting Space Goals

Rovers make Mars the center of attention, but is Bush's space exploration plan good science?

February 23, 2004 | A version of this story appeared in Volume 82, Issue 8

An artist's depiction of one of the twin Mars rovers shows the probe in action.
An artist's depiction of one of the twin Mars rovers shows the probe in action.

Thanks to a series of breathtaking images beamed back to Earth by two golf-cart-sized rovers, Mars has once again captivated our imagination. The National Aeronautics & Space Administration's Mars website has received more than 4 billion hits since January for the latest information about the agency's most recent successful mission.

Coinciding with our renewed fascination with the red planet was the announcement on Jan. 14 of a new space exploration policy by President George W. Bush. The policy lays out a plan to return humans to the moon as a stepping stone to other solar system destinations, namely Mars. The projected cost is a mere $1 billion in new funds over a five-year period as a start. After that time, NASA expects the cost of the plan to be covered by inflationary budget growth.

The allure of Mars is understandable: It's the most Earth-like planet we know of, and it shows evidence of ancient water beds. There's also speculation that the planet might even have nurtured microscopic life. For these reasons, Mars has been the target of a number of probes, from the first successful Mars orbits by the Mariner missions in the 1960s to the 1996 Pathfinder mission with its minirover, Sojourner, to the current rover missions.

In a way, the success of NASA's most recent rovers--Spirit and Opportunity--serves as a foundation for the President's plan to one day put humans on Mars. For one thing, it provides evidence that NASA can operate within a budget. The total cost for both rover missions, which in a short time have sent back quantities of new information about martian soil and rocks, was about $820 million. In the past, NASA has not been known for its fiscal responsibility, as evidenced by the cost overruns of the space shuttle and the space station.

We now also have some confidence in NASA's ability to land a craft on Mars safely. This is by no means a small feat. Together, the world's space agencies have a spotty track record when it comes to Mars missions, which have suffered a 50% failure rate. But whether the failures were due to internal snafus or the inherent dangers of space, it's hard to imagine NASA ensuring astronaut safety with a sudden, giant leap in success rates. Additionally, NASA will also have to develop technology to protect astronauts from cosmic radiation and long-term space effects.

Assuming, however, that NASA could successfully develop the necessary technology within the outlined fiscal constraints, the question then becomes: What can humans add to the exploration of Mars and other solar system destinations that robotic probes could not achieve alone for a fraction of the cost? Or to put it another way: Is it worth risking human lives on missions that do more to fulfill our much-vaunted need to feel like explorers than to further science?

The Apollo missions to the moon were great for our sense of accomplishment, but the information gathered by the unquestionably heroic astronauts could have been collected more easily, safely, and cheaply with robots. In fact, that is exactly what the President's plan is calling for: robotic survey missions to the moon to scout out available resources in preparation for setting up a crewed lunar station.

For now, we think NASA should hold off on any plans to send humans beyond lower Earth orbit and should focus its resources on robotic missions. After all, the probes seem to be doing the job ably. NASA's Global Surveyor and Mars Odyssey spacecrafts continue to orbit Mars, and it was Odyssey's discovery of hematite, a mineral frequently formed in the presence of water, that determined the location of the landing site of one of the rovers.

Unencumbered by a need for oxygen, water, and food, Spirit and Opportunity continue to obey commands sent to them from Earth. The radiation that human explorers would have to be protected from will take its toll on the probes' equipment, and they'll eventually break down. But with the cost savings of robotic missions over human ones, we can afford to send up a number of these probes to pick up where the last one left off.

Besides, there are many places we just can't go ourselves. For example, no peopled craft could handle the sweltering heat of Venus or the crushing gravity of Jupiter. But NASA's Magellan orbiter peered under Venus' heavy CO2 atmosphere and mapped its surface. The Galileo spacecraft showed us secrets of Jupiter and its moons, including Europa, which may have a liquid ocean underneath a coating of ice.

Some may also argue, as President Bush did during his presentation of the new plan, that "the human thirst for knowledge cannot be satisified by even the most vivid pictures or the most detailed measurements." Without a human space mission to look forward to, some say, our children will grow up without the desire to strive for greatness. Balderdash. It's quite clear that Americans are dazzled and inspired by the remote accomplishments of the rovers.

Right now, we can't even maintain the health of our own global environment, much less shoulder the responsibility of safely sending humans to visit and then colonize the moon and Mars. So until our knowledge and technology catch up with our ideals, let's let the robots do our space exploration for us. We can still enjoy the thrill of discovery and feel like pioneering explorers, without an unacceptable cost.

Views expressed on this page are those of the authors and not necessarily those of ACS.



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