NASA Administrator Mike Griffin announced Oct. 31 that the agency would mount a shuttle mission to save and upgrade the Hubble Space Telescope, thereby ending a dark episode in the history of the American space agency.
The crisis began Jan. 16, 2004, when then-NASA Administrator Sean O’Keefe just two days after President’s George W. Bush’s declaration of the new Vision for Space Exploration chose to announce his decision to desert the Hubble Space Telescope.
According to Mr. O’Keefe, Hubble needed to be abandoned because — despite four successful previous shuttle missions to the Hubble — NASA now realized after the Columbia disaster that missions to Hubble were too dangerous to risk. Instead, the space agency would limit its future shuttle flight plans to a supposedly much safer program of 29 missions to the international space station (ISS).
O’Keefe’s statement was categorically absurd. While ISS missions that manage to reach their target have a potential safe haven at the space station, which Hubble missions lack, Hubble flights have much better abort options than those to the ISS. When they depart from Cape Canaveral, Fla., Hubble missions fly east-southeast, and thus have the possibility to ditch in warm tropical waters. In contrast, ISS flights leave the Cape traveling northeast, and their crews face the bleak prospect of aborts into the frigid waters of the North Atlantic, where their chances for survival would be much less.
Furthermore, Hubble missions, because they take off more lightly laden than ISS flights, can abort to orbit with engine out much earlier. For example, in order to be able to abort to orbit on an ISS mission such as STS-113 (Endeavor), all three shuttle main engines must fire for a full 282 seconds before one cuts out. In contrast, on Hubble missions such as STS-103 (Discovery), only 188 seconds of full three-engine operation is required. This lower full-power time requirement for Hubble missions is a critical safety advantage, because the maximum time that either ISS or Hubble missions can attempt a Return to Launch Site (RTLS) abort is about 232 seconds. Thus Hubble missions have a 50 second overlap during which either a RTLS or an orbital abort is possible. ISS missions, on the other hand, have a 50 second gap in which neither is possible.
Finally, the Hubble orbit has a much lower micrometeorite and orbital debris hazard than that of the ISS. So, in short, there is no reason to believe that a Hubble mission is more dangerous than one flight to the ISS, let alone 29. Yet Mr. O’Keefe chose to blandly ignore the data and proceeded to abandon Hubble — the most productive scientific instrument in human history, and by far the most important accomplishment of NASA’s manned spaceflight program since Apollo.
But faced with powerful political opposition from senators whose opinions he could not dictate, Mr. O’Keefe attempted a diversionary tactic by ordering a study of the feasibility of a robotic rescue mission using unproven — indeed nonexistent– technology as an alternative. The acceptance of this nonsense would have represented a complete abandonment of NASA’s engineering discipline, which requires that mission-critical technology be mature before it is used.
The Mars Society responded to Mr. O’Keefe’s decision to desert Hubble with an immediate denunciation and a forceful and sustained counter-campaign. It does not matter what the space agency’s nominal goals are if it does not have integrity. A NASA too timid to return to Hubble would never be able to reach for the Moon or Mars. It is impossible for any engineering organization to operate competently for any purpose if it becomes accepted practice that management has the right to deny technical reality on the basis of political convenience or arbitrary whim. Engineering needs to be done on the basis of truth.
So now the decision has been made to save the space telescope. It’s the right decision, even though the Hubble flight will be risky. Yes, risky – no more so than an ISS mission, but risky nevertheless. It could fail. Despite all the hard work done by the shuttle team since the Columbia accident to improve safety, the best bet is that the risk of loss of future shuttle missions is about the same as past ones — 2 percent. The shuttle is a very complex system, with thousands of potential failure modes; we’ve eliminated two.
Yet it is the right decision, because it averts a historic crime against science. It is the right decision, because it represents the victory of reason. It is the right decision because it reasserts NASA’s commitment to its mission. It is the right decision, because it saves the honor, and the soul, of NASA.
Robert Zubrin is president of the Mars Society (www.marssociety.org) and author of the books The Case for Mars (1996), Entering Space (1999), and Mars on Earth (2003).