From BBC News World Edition
Monday, 3 February, 2003, 00:41 GMT
People across the US are mourning the astronauts
The space shuttle Columbia may have been shedding heat-protection tiles as it flew over the United States on its re-entry into the earth's atmosphere, Nasa officials have said.
At the latest press conference given by the US space agency, officials gave more details about temperature sensor readings during the last few minutes of the orbiter's flight.
The new information came as Nasa officials confirmed that remains of all seven astronauts on board Columbia have been found.
Nasa has vowed to leave "no stone unturned" in its investigation into why the space shuttle disintegrated just minutes before its scheduled landing on Saturday.
Data reviewed by investigators showed the left side of the shuttle started to rise in temperature as it passed over California and New Mexico and that the shuttle was experiencing increased drag on the left-hand side of the vehicle.
.instructionsheader{
font-family: verdana,arial;
color: #666633;
font-size: 11px;
text-decoration:none;
font-weight:bold;}
.instructions{
font-family: verdana,arial;
color: #000000;
font-size: 11px;
text-decoration:none;}
Space Shuttle Programme Manager Ron Dittemore said the detection of increased drag could have been an indication that the shuttle had lost heat-protection tiles or that the tiles had become uneven.
"But I have to caution you that this is a very fluid situation and what we understand today may change in the coming days," he stressed.
 A piece of foam hit the shuttle's left wing shortly after lift-off
|
Experts are carrying out a painstaking analysis of the mass of data transmitted back from the shuttle in the last minutes of its flight.
Another key part of the investigation will be analysing the pieces of the shuttle which rained down over the southern US - a process likely to take months.
Possible damage to Columbia's protective thermal tiles on its left wing had already been flagged up as a cause for concern.
The wing was hit by a piece of insulating foam which peeled away from the external fuel tank a little more than a minute into Columbia's launch on 16 January.
The incident was spotted and checked at the time, Nasa officials said. But on Saturday they acknowledged they could not now rule out a connection.
As Americans mourned the deaths of the shuttle's seven astronauts, police teams scoured large areas in Texas for shuttle fragments.
Already accusations are being levelled that Nasa chiefs ignored a series of safety warnings.
But these were rejected by Nasa administrator Sean O'Keefe, who said every safety concern was tackled before a shuttle launch.
In some Morton-Thiokol memos between engineers, the sealant putty was nicknamed either "lucky putty" or "magic putty".
I merely quoted them.
What we see in NASA re the other vulnerabilities of the Shuttle incuding tile damage similar to what is described in this part of the Challenger Commission report. Here is another quote. Notice the part "they got away with it last time."
EARLY DESIGN
The Space Shuttle's Solid Rocket Booster problem began with the faulty design of its joint and increased as both NASA and contractor management first failed to recognize it as a problem, then failed to fix it and finally treated it as an acceptable flight risk.
Morton Thiokol, Inc., the contractor, did not accept the implication of tests early in the program that the design had a serious and unanticipated flaw. NASA did not accept the judgment of its engineers that the design was unacceptable, and as the joint problems grew in number and severity NASA minimized them in management briefings and reports. Thiokol's stated position was that "the condition is not desirable but is acceptable."
Neither Thiokol nor NASA expected the rubber O-rings sealing the joints to be touched by hot gases of motor ignition, much less to be partially burned. However, as tests and then flights confirmed damage to the sealing rings, the reaction by both NASA and Thiokol was to increase the amount of damage considered "acceptable." At no time did management either recommend a redesign of the joint or call for the Shuttle's grounding until the problem was solved.
FINDINGS
The genesis of the Challenger accident -- the failure of the joint of the right Solid Rocket Motor -- began with decisions made in the design of the joint and in the failure by both Thiokol and NASA's Solid Rocket Booster project office to understand and respond to facts obtained during testing.
The Commission has concluded that neither Thiokol nor NASA responded adequately to internal warnings about the faulty seal design. Furthermore, Thiokol and NASA did not make a timely attempt to develop and verify a new seal after the initial design was shown to be deficient. Neither organization developed a solution to the unexpected occurrences of O-ring erosion and blow-by even though this problem was experienced frequently during the Shuttle flight history. Instead, Thiokol and NASA management came to accept erosion and blow-by as unavoidable and an acceptable flight risk.
Note that tile damage at launch has been regarded as unavoidable and an acceptable flight risk until now.
Specifically, the Commission has found that:
1. The joint test and certification program was inadequate. There was no requirement to configure the qualifications test motor as it would be in flight, and the motors were static tested in a horizontal position, not in the vertical flight position.
2. Prior to the accident, neither NASA nor Thiokol fully understood the mechanism by which the joint sealing action took place.
3. NASA and Thiokol accepted escalating risk apparently because they "got away with it last time." As Commissioner Feynman observed, the decision making was:
"a kind of Russian roulette. ... (The Shuttle) flies (with O-ring erosion) and nothing happens. Then it is suggested, therefore, that the risk is no longer so high for the next flights. We can lower our standards a little bit because we got away with it last time. ... You got away with it, but it shouldn't be done over and over again like that."
4. NASA's system for tracking anomalies for Flight Readiness Reviews failed in that, despite a history of persistent O-ring erosion and blow-by, flight was still permitted. It failed again in the strange sequence of six consecutive launch constraint waivers prior to 51-L, permitting it to fly without any record of a waiver, or even of an explicit constraint. Tracking and continuing only anomalies that are "outside the data base" of prior flight allowed major problems to be removed from and lost by the reporting system.
5. The O-ring erosion history presented to Level I at NASA Headquarters in August 1985 was sufficiently detailed to require corrective action prior to the next flight.
6. A careful analysis of the flight history of O-ring performance would have revealed the correlation of O-ring damage and low temperature. Neither NASA nor Thiokol carried out such an analysis; consequently, they were unprepared to properly evaluate the risks of launching the 51-L mission in conditions more extreme than they had encountered before.
She was proud to be representing her country
