THE Challenger disaster spurred NASA to tighten up on safety; so will Wednesday's Titan IV rocket explosion at Vandenburg Air Force Base. But there's still a critical area where complacency rules - computer software.
"Many of the same kinds of mistakes that played a role in the Challenger accident are now being repeated with the shuttle flight software," warns University of Washington scientist Nancy Leveson. She says there is a belief among some shuttle staffers that safety is treated with less importance in their area than on unproven programs.
Professor Leveson was speaking as chair of a National Academy of Sciences committee that released a study of space software safety earlier this summer. It has stirred little public comment, probably because software is an unglamorous subject. Yet the shuttle depends on its computers for all its operations, including spacecraft handling and landing. Defective software could be just as deadly as defective rockets.
Actually, software safety transcends the shuttle. It's critical for building and operating NASA's planned space station and the agency's increasingly sophisticated unmanned missions. The agency is now engaged in some of the most complex software projects ever attempted.
Making sure this software is sound is as demanding as ensuring the performance of space hardware and operating personnel. The committee says its report should not be taken as a "wholesale indictment" of NASA's effort to do this. But it leaves no doubt that this effort can be tightened up.
NASA relies too much on contractors to develop software and set standards. It needs more in-house competence to set its own standards and see they are met. One proposed software guideline has been in draft form for four years.
The committee made 22 recommendations to ensure software safety. Some of these hark to earlier studies, including the 1986 official report of the Challenger accident investigation. The committee notes that if NASA had heeded these the present report might not have been needed.
It's heartening to see the care with which NASA is handling Discovery's upcoming nine-day mission. Controllers have postponed the launch three times since mid-July - twice to correct technical problems and now to avoid the August meteor showers.
The agency should show the same care for the safe operation of the software that will make the system go.