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Post by laurel on Apr 5, 2008 14:11:30 GMT -4
I have a question about Scott Carpenter and how he overshot his landing site by 250 miles on Aurora 7. I've heard there is some controversy about this. Some people say it was Carpenter's fault because he wasn't paying attention and some people say his spacecraft had a mechanical problem like a faulty autopilot. Which is the more likely explanation? I guess that strictly speaking, this isn't exactly an Apollo question, but could anyone on here shed some light on it for me?
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Post by Czero 101 on Apr 5, 2008 14:21:14 GMT -4
From Wikipedia - Mercury / Atlas 7The "fireflies" were the same phenomenon that John Glenn reported. Carpenter saw them too, and was able to determine that the phenomenon was a result of ice particles that had been shaken loose from the capsule. Cz
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Al Johnston
"Cheer up!" they said, "It could be worse!" So I did, and it was.
Posts: 1,453
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Post by Al Johnston on Apr 5, 2008 14:41:37 GMT -4
I'd imagine there are elements of both sides to it: his spacecraft wasn't functioning properly, but a pilot with the "Right Stuff" was expected to overcome such trivialities and perform the mission anyway... ;D
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Post by Ginnie on Apr 5, 2008 15:41:54 GMT -4
I have a question about Scott Carpenter and how he overshot his landing site by 250 miles on Aurora 7. I've heard there is some controversy about this. Some people say it was Carpenter's fault because he wasn't paying attention and some people say his spacecraft had a mechanical problem like a faulty autopilot. Which is the more likely explanation? I guess that strictly speaking, this isn't exactly an Apollo question, but could anyone on here shed some light on it for me? This is the sequence of events that I've been able to come up with: Six times the attitude control jets are accidently turned on, wasting fuel The ASCS doesn't hold the ships attitude properly Thus during re-entry Scott must align the spacecraft by means of the horizon window reference while 'flying by wire'. So now the retro-rockets do not go off automatically (they slow the ship to allow re-entry). Scott fires them manually, but is five seconds late. Apparently this is 'good enough', but not perfect. Fuel is so low that Scott does not use power to guide the craft. At 80,000 feet all fuel is exhaused. At 50,000 feet the Aurora 'swings around dangerously, but all Scott can do is ride it out'. Parachute fired at 25,000 feet. Main chute deployed at 9,000 feet. At the end of the communications blackout Scott tries to reach Mercury Command but can't. Hears Grissom (from MC) broadcasting that Scott is 200 miles off course. See the whole mission report: ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19620004691_1962004691.pdf(you may be interested in pages 110-116) Note that MC said that they should be by in about an hour to pick Carpenter up - in fact it turned out to be almost two. EDIT: Cool NASA simulated animation of the new moon mission: anon.nasa-global.edgesuite.net/anon.nasa-global/NASAHD/Lunar_Surface/LunarSurface_HD_480p.wmv***HB ALERT: This is a simulation ONLY. Not a genuine Moon Landing. ***
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Post by Ginnie on Apr 15, 2008 19:09:38 GMT -4
I'm reading 'Moonshot:The Inside Story of America's Race to the Moon' by Deke Slayton and Alan Shepard. Here is how the Carpenter-Fireflies episode is described:
...But they made a last moment decision to let Carpenter stay in orbit if he would go into a "drifting mode", which would conserve his remaining fuel. Scott judged it a good idea, and he floated in weightlessness, enjoying every moment. Entering a sunrise, he banged his head against the inside wall of his capsule. It was a fortuitous blow with unexpected payoff. The moment he struck the wall, he was flying through a swarm of John Glenn's "fireflies." Again he struck the capsule bulkhead, and more fireflies showered into view. Despite his low thruster fuel, he fired the jets, swung around the capsule, and proved beyond a question the mysterious fireflies originated from vapor vented from the spacecraft. Vapor produced by the human body. The astronaut's body generated moisture. As he perspired, and especially when he exhaled, body moisture and gases were removed from the spacecraft, dumped through an external vent in the side of the capsule. The instant this moisture entered the cold vacuum of space, it froze into frost and ice particles. Some swarmed about the capsule or floated away; others clung to the spacecraft side, to be knocked off when Scott thumped the wall. When the sun angle was just right, at sunrise or sunset, these particles became the famed "celestial fireflies." Scratch one mystery. Carpenter somehow began to fall behind in the checklists. As the time came for him to fire his retro-rockets, a controller at the Hawaii tracking station reported, "We had the impression he was very confused about what was going on. But it was very difficult to say whether he was confused or preoccupied." For undetermined reasons Carpenter fired the retros three seconds late, resulting in a twenty-five-degree error om Airpra Seven's yaw position. "My fuel, I hope it holds out," Carpenter said as the descent began. It didn't and he had to release his drogue and main chutes early to stabilize a badly oscillating spacecraft. A few seconds delay at orbital speed translates into big mileage errors. Because of the late retro-firing and the misalignment, Aurora Seven whooshed 250 miles beyond its intended landing point in the Atlantic.
So it does seem like the fireflies distracted him and he wasted fuel and delayed firing the retro rockets.
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Post by Jason Thompson on Apr 17, 2008 8:31:49 GMT -4
I'd say a combination of both factors played a part. Carpenter is interviewed on the Spacecraft Films Mercury DVD set, and the following statements stuck out when listening to it.
'I was more interested in where I was than in what got me where I was' (referring to his interest in the environment versus the spacecraft).
'If you talk to Chris Kraft it was failure of the man, if you talk to me failure of the machine. Where the truth is I don't know.'
'I didn't manage my fuel supply very well on the second orbit.'
He also brought up the fireflies early in the interview, indicating a strong interest in them, and it does seem he wasted some time and fuel confirming what they were when he should have been doing other things. He mentioned a faulty yaw indicator as well, which probably contributed to his directional error during retrofire.
I'm also going to look through a couple of the books I have on the subject (the books by Kraft, Kranz and Slayton) and see what I can glean from those.
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Post by laurel on Apr 17, 2008 9:28:27 GMT -4
I know that Gene Kranz said in his book, "A crewman distracted and behind in the flight plan is a risk to the mission and himself." He also said that the systems monitor thought Carpenter hadn't done a gyroscope alignment when he was supposed to and that John Llewellyn was angry with Carpenter for saying, "I didn't know where I was and they [Mission Control] didn't either." Thanks for the detailed answers, everyone.
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