The rover managers have successfully tested methods for extracting Opportunity from the sand. Principal investigator Steve Squyres has said all along that it will be a slow process:
the design of the LOX tank was a disaster waiting to happen: fly it enough and it will blow up
No. The fan motor design that concerns you so was not at fault in this accident. This particular tank was damaged, with partially bared wires that touched when the tank was stirred; it was indeed a disaster waiting to happen. But there was nothing inherently unsafe in the tank design. Unless you have more specific information on the design of the fan motor than I do?
it is not safe to spark in pure oxygen
No argument there! Of course this would not have been news to the tank designers either.
No, the wiring overheated on the ground, as the test conductors ran the internal tank heater for hours to boil off the LOX inside. The tank contents did not empty as quickly as usual because the tank fill pipe had been dislodged when the tank was dropped two inches during installation some months before. Because the tank heater was built for 28V and the older ground test equipment delivered 65V, the heater thermostat failed, and the tank heater stayed on 100% of the time instead of cycling on and off. The intense heat that built up in the well-insulated tank damaged the wiring in the tank.
the LOX would have cooled the wires so that they wouldn't have reached ignition temperature
Ignition occurred when the wires with damaged insulation came into contact with each other and arced. The arc was hot enough to induce combustion in the wire insulation.
Yuri Gagarin urinated on the bus tires in this fashion, and all crews launched from Baikonur since then have repeated this tradition for luck. That includes the first ISS crew, commanded by NASA astronaut Bill Shepard.
You're blaming the loss of Columbia on the orbit chosen for the ISS???
1) The reason Columbia could not rendezvous with the ISS is not because the ISS is in some kind of undesirable orbit. The reason is that the shuttle was launched into an orbit from which it could not reach the ISS. The shuttle has a limited capability to change its orbit, and it wasn't enough to move into the same orbit as the ISS. You may have noticed some discussion since the tragedy about launching shuttles only to the ISS, save for Hubble repair missions.
2) The whole question of orbits presupposes that Mission Control would have chosen to have Columbia rendezvous with the ISS, if possible. This is obviously not true. The flight director Linda Hamm (shades of Larry Mulloy - "prove to me it isn't safe") made it clear that she saw no issue with the foam impact. There was never a chance that Houston would have ordered that rendezvous. Any such discussion is only Monday-morning quarterbacking (or hindsight, for our non-American readers).
FWIW, on the most recent Soyuz flight, the very first flight of a new model, it suffered a significant problem (near complete failure) with it's [sic] guidance computer.
Yet the consequences of this failure were no more than missing the targeted landing point, and experiencing higher (but still tolerable) deceleration during reentry. The guidance failure was unfortunate, but the backup guidance mode was completely successful. The only effect on the mission was a delay in recovering the reentry vehicle and crew. The American media made more of this than was justified by the facts.
A blunt body like the Soyuz is clearly a more robust design than any lifting body can be in the case of a guidance failure during reentry.
Don't remember where I read it, but I agree with the person who said that space flight will not be affordable until we build our launch vehicles in something more like a foundry than a clean room.
Seems unlikely, since the shockwaves from bow and stern can never interfere with each other, either constructively or destructively. The bow and stern shocks travel at the same speed (i.e., the speed of sound) and so the stern wave can never catch up to the bow wave to combine with it.
Not to mention that there are many more shockwaves of varying strength riding on various portions of the airframe.
Wish they'd do something like this for subsonic airliners, though, and tailor it for their normal crusing altitude.
For those who have asked how much of a reduction in sonic boom was achieved:
The following URL says the peak pressure was reduced by one third, but there was very little difference in the sound of the boom on the ground. This was a better result than expected, since they did not expect to hear _any_ difference.
After all, this was _not_ an attempt to fly supersonically without generating a sonic boom, despite the misleading title of this thread. Instead, it was a (very successful) attempt to valid the CFD models used to design the aircraft nose modifications and predict the reduction of the pressure wave on the ground.
Now that they have proved that their method works, they can work on more noticeable reductions.
Slashdot Mirror
The rover managers have successfully tested methods for extracting Opportunity from the sand. Principal investigator Steve Squyres has said all along that it will be a slow process:
http://athena.cornell.edu/news/mubss/
the design of the LOX tank was a disaster waiting to happen: fly it enough and it will blow up
No. The fan motor design that concerns you so was not at fault in this accident. This particular tank was damaged, with partially bared wires that touched when the tank was stirred; it was indeed a disaster waiting to happen. But there was nothing inherently unsafe in the tank design. Unless you have more specific information on the design of the fan motor than I do?
it is not safe to spark in pure oxygen
No argument there! Of course this would not have been news to the tank designers either.
In flight, the wiring overheated
No, the wiring overheated on the ground, as the test conductors ran the internal tank heater for hours to boil off the LOX inside. The tank contents did not empty as quickly as usual because the tank fill pipe had been dislodged when the tank was dropped two inches during installation some months before. Because the tank heater was built for 28V and the older ground test equipment delivered 65V, the heater thermostat failed, and the tank heater stayed on 100% of the time instead of cycling on and off. The intense heat that built up in the well-insulated tank damaged the wiring in the tank.
the LOX would have cooled the wires so that they wouldn't have reached ignition temperature
Ignition occurred when the wires with damaged insulation came into contact with each other and arced. The arc was hot enough to induce combustion in the wire insulation.
Yuri Gagarin urinated on the bus tires in this fashion, and all crews launched from Baikonur since then have repeated this tradition for luck. That includes the first ISS crew, commanded by NASA astronaut Bill Shepard.
You're blaming the loss of Columbia on the orbit chosen for the ISS???
1) The reason Columbia could not rendezvous with the ISS is not because the ISS is in some kind of undesirable orbit. The reason is that the shuttle was launched into an orbit from which it could not reach the ISS. The shuttle has a limited capability to change its orbit, and it wasn't enough to move into the same orbit as the ISS. You may have noticed some discussion since the tragedy about launching shuttles only to the ISS, save for Hubble repair missions.
2) The whole question of orbits presupposes that Mission Control would have chosen to have Columbia rendezvous with the ISS, if possible. This is obviously not true. The flight director Linda Hamm (shades of Larry Mulloy - "prove to me it isn't safe") made it clear that she saw no issue with the foam impact. There was never a chance that Houston would have ordered that rendezvous. Any such discussion is only Monday-morning quarterbacking (or hindsight, for our non-American readers).
FWIW, on the most recent Soyuz flight, the very first flight of a new model, it suffered a significant problem (near complete failure) with it's [sic] guidance computer.
Yet the consequences of this failure were no more than missing the targeted landing point, and experiencing higher (but still tolerable) deceleration during reentry. The guidance failure was unfortunate, but the backup guidance mode was completely successful. The only effect on the mission was a delay in recovering the reentry vehicle and crew. The American media made more of this than was justified by the facts.
A blunt body like the Soyuz is clearly a more robust design than any lifting body can be in the case of a guidance failure during reentry.
Don't remember where I read it, but I agree with the person who said that space flight will not be affordable until we build our launch vehicles in something more like a foundry than a clean room.
Seems unlikely, since the shockwaves from bow and stern can never interfere with each other, either constructively or destructively. The bow and stern shocks travel at the same speed (i.e., the speed of sound) and so the stern wave can never catch up to the bow wave to combine with it. Not to mention that there are many more shockwaves of varying strength riding on various portions of the airframe. Wish they'd do something like this for subsonic airliners, though, and tailor it for their normal crusing altitude.
For those who have asked how much of a reduction in sonic boom was achieved:
The following URL says the peak pressure was reduced by one third, but there was very little difference in the sound of the boom on the ground. This was a better result than expected, since they did not expect to hear _any_ difference.
After all, this was _not_ an attempt to fly supersonically without generating a sonic boom, despite the misleading title of this thread. Instead, it was a (very successful) attempt to valid the CFD models used to design the aircraft nose modifications and predict the reduction of the pressure wave on the ground.
Now that they have proved that their method works, they can work on more noticeable reductions.
http://209.157.64.200/focus/f-news/973267/posts