For the space geeks out there, you know exactly what February 20, 1962 (and yes last week was the 51st anniversary of one of the greatest moments in U.S.A's spaceflight history) means in the annals of the US's spaceflight.
February 20, 1962 was the first time NASA had sent a manned craft into space with the intent of circling the globe. The capsule in question was Freedom 7 and the pilot (I know, stretching the pilot on a Mercury) was John Glenn.
But how many of you remember how close we came to losing Freedom 7 and Glenn on that same flight?
The flight play called for seven orbits but shortly after launch NASA noticed that Freedom 7's yaw thruster had malfunctioned which would mean that the mission would have to be drastically cut back.
Freedom 7's problems didn't end there. Almost immediately ground control received a warning that the "flotation ring " had been deployed. The ring was carefully stowed behind the heat shield and was only deployed after landing. The thruster pack is discarded during re-entry and the heat shield when atmosphere heating is no longer a problem. But when controllers discovered the floatation ring error, they knew this could only mean that the heat shield had partially or completely detached
This means that astronaut Glenn could perish on re-entry.
Since the thruster package still seemed intact and firmly attached, NASA decided to have Glenn fired a small de-orbit burn but do something unprecedented, leave the maneuvering pack still attached in hopes that if the heat shield was detached the pack would hold the shield in place.
Since a whole lot of things went right, John Glenn is still will us as are some very fortunet
There is a wealth of information on this flight at nasa and this report from the wiki
3 comments:
If I remember right the heat shield was made of cork, cork is the bark of a oak tree (the cork oak tree).
The capsules frame was of titanium, covered in steel and beryllium shingles. The base of it was made of a beryllium heat sink for guard against the re-entry heat build up. Later space craft use the ablative style heat shields. In other words,
the shield breaks up and vaporizes, instead of the ship itself.
Lynn
Yes if we look at the study done at the time (http://history.nasa.gov/SP-4201/ch5-7.htm) we see there was 2 camps that had completely different ideas on thermal management of reentry. One idea was to "sink" the heat with various amalgams of copper type metals which had proved very successful on ballistic missiles, with the other camp leaning towards ablation shields made of materials such as beryllium, and by 1958 all contractors were asked to consider this material in future bids and contracts. Of course any material that wasn't to be "brought back" didn't need to meet these requirements, hence the horrifying sight of parts of Glenn's ship flying past the port during reentry.
Now I can not confirm or deny that cork was not used in the manufacture of the Mercury capsule, but as a primary heat sink, well all we have to do is look to recent history to know how incredibly hot reentry is.
Kall in this matter is 100 percent dead on.
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