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What Gets Left Behind?

By Robert Gounley

Space exploration is due for a transition-returning astronauts to the Moon and onward to Mars. These are heady times and cyberspace is abuzz with excitement. For now, it matters little whether you regard the Moon or Mars as the most important destination or whether you think private enterprise or government programs should help place footprints on another world. Chances are, you hear something in President Bush's message to give you encouragement.

Transitions, unfortunately, are inherently awkward times. Amidst the jubilation, there's always something that gets left behind. It may be something highly visible or something easily overlooked. Only by exercising the greatest care can we avoid losing something irreplaceable without making preservation our only objective.

Take the Hubble Space Telescope, for example. It has produced more scientific discoveries than any other space mission in this generation. Its continued operation was possible only because it was designed to be tended by astronauts, and the Space Shuttle was available for regular maintenance calls. That seemed like a safe and reliable assumption for the duration until Hubble's replacement in ten years by the James Webb Space Telescope.

That assumption no longer holds. Under new safety guidelines, shuttles must be capable of on-orbit recovery from a launch accident like the one that doomed Columbia and its crew. That's most easily done when a shuttle visits the International Space Station (ISS). If things go horribly wrong, at least the crew can remain on orbit until a rescue mission is launched.

Unfortunately, the orbits of Hubble and the ISS are significantly different. To accommodate access by the Russian Soyuz spacecraft-currently the only means of reaching the station-ISS travels in an orbit inclined 52 degrees relative to the equator. Hubble orbits at 28 degrees inclination. A shuttle can launch into one orbit or the other; it can not carry enough fuel to travel from one to the other. Thus, for safety reasons, NASA plans no further servicing missions to Hubble, instead allowing its operations to continue until enough components fail to make useful observations impossible. That could be next year or next decade-without preventative maintenance, Hubble has no defense against failures that all spacecraft are prone to.

Is safety an insurmountable technical obstacle to further Hubble servicing? No, it isn't. One answer might be to prepare a second shuttle for crew rescue in case the first runs into trouble. That would be extremely expensive and tie up a scarce national resource required for completion of the Space Station. Some people propose designing equipment to quickly inspect and repair the shuttle without the convenience of a space station to work from. Others suggest that launching to Hubble is safer than visiting the space station and requires no additional safety measures. There is no shortage of ideas, although all have some formidable challenges.

Ultimately, a Hubble rescue is a question of priorities. The proposed budget to fund the Moon/Mars initiative calls for retiring the Space Shuttle soon after completion of the space station. That affords little opportunity to amortize investments to restore shuttle capabilities we have taken for granted. Even if we fly to an unimproved shuttle to Hubble, that mission's cost must still be paid for. Without NASA funding greater than Bush's proposed budget (a difficult feat given our current record deficit) fixing Hubble will either take money from new initiatives or other existing programs, each with their own constituencies.

I hope Hubble is rescued. It doesn't matter to me if a dedicated shuttle mission or a privately financed servicing robot does it. As much as I welcome human deep-space missions, Hubble's immediate benefits are too great for me to be unmoved by their near-term loss.

Change happens in spite of protests from curmudgeons like me. Sometimes we are surprised and have to reconsider our assumptions. Still, I can't help but wonder if in the rush to put new footprints on other worlds tomorrow, we may give up something valuable today.