NASA Study Whether Misaligned Fuel Tanks Caused Shuttle Leak
WASHINGTON (AP) _ NASA engineers are focusing on a small misalignment of fuel tanks and spacecraft on two space shuttles as they search for the elusive hydrogen leaks that have grounded the shuttle fleet.
The continuing mystery of the leaks is throwing the shuttle schedule into disarray and threatens to postpone at least two missions this summer, officials said Monday.
Most of the 35 orbiter-tank combinations flown so far have had some misalignments, but the two found in the shuttles with the leaks are the largest to date, space flight director William B. Lenoir said.
″One of the areas we are looking at is the angle of connection between the external tank and the orbiter,″ Lenoir said. ″Ideally you think of them to be really aligned (but) it’s never perfect, it’s always some small degree of misalignment.″
Lenoir said the leak problem - which shows up while the tank is being filled with supercold liquid hydrogen a few hours before flight - must be fixed within a few weeks to keep NASA anywhere near its ambitious flight schedule.
The schedule called for a Columbia launch in May on an astronomy mission, Atlantis in July, Columbia again in August and then Discovery in October.
The hydrogen leak on Columbia in May and the discovery last week of a similar leak on Atlantis scrambled that schedule and Lenoir said it is unclear now if the agency can recover in time to fly all the missions this year.
Discovery must go in October to take advantage of a planetary alignment that occurs only once every two years. The shuttle’s cargo is the Ulysses science probe that is to study the sun.
″We’re right on the edge of the point where two flights no longer fit in the schedule before the launch of Ulysses,″ said Lenoir. Fixing the leak, he said, will have to be quick and simple to avoid more changes in the NASA launch schedule.
The shuttle orbiter - the airplane-like vehicle in which astronauts fly - is attached to the 154-foot-long fuel tank at three points, two on the lower end and one on the upper.
Fuel flows from the tank to the orbiter’s three engines through a 17-inch pipe that disconnects when the tank is empty and begins its fall back to Earth.
One of the lower attachment points on Columbia’s tank is .160 of an inch higher than the other and the one on Atlantis is off by .150 of an inch, said shuttle boss Robert L. Crippen.
That small misalignment is well within the tolerance built into the shuttle system, he said.
But whether that is enough of a deviance to put strain on the fuel line, also near the bottom of the tank, is being studied by one of the four teams NASA has set up to look into the problem.
Lenoir said he hoped to get some answers by Thursday. Parts of Columbia are being tested in a laboratory. Atlantis was undergoing tests - with helium substituting for the volatile liquid hydrogen - while still on the launch pad Monday, despite severe thunderstorms and high winds that raked the Kennedy Space Center in Florida.
″We’ve been unable to say, ’Hey, that’s a problem area,‴ Lenoir said. ″On the other hand, because of their coincidence we are not stopping there.″
NASA’s science chief, Lennard Fisk, sought to put a brighter view on NASA’s other headache, the faulty mirror on the $1.5 billion Hubble Space Telescope that prevents the accurate focusing that scientists sought.
″There are two characteristics of the people who work for NASA,″ he said. ″We’re stubborn and we’re clever. We’re going to make this thing work.″
NASA is consulting with experts in image processing - using technology to enhance pictures received from the telescope.
″There is growing optimism that we will be successful,″ Fisk said. ″Six months from now, a year from now, I expect you all to ooh and ahh over the picture that Hubble is going to produce and of course, compliment the current management of NASA for their success in pulling it off.″