jeudi 15 avril 2010

Interview de Bruce McCandless, astronaute et premier homme à utiliser le MMU

Bruce McCandless, ancien pilote de l'US Navy et ingénieur aérospatial, est un astronaute de la NASA sélectionné en 1966 dans le Groupe 5.
Il a participé au Programme Apollo en tant que ''support crew'' pour Apollo 14.
Puis il a été doublure en tant que pilote du CMS de la mission Skylab 2.
Il fait partie de l'équipe qui a conçu le M-509, fauteuil autonome qui sera testé dans Skylab.
Il est surtout connu pour avoir été le responsable du développement du MMU - Manned Maneuvring Unit, qui est ce petit engin fixé au dos de l'astronaute utilisé dans les EVA de la navette.
Lors de la mission STS-41B, en 1984, il sera le premier à l'utiliser et deviendra aussi le ''1er homme satellite''. Il sera le 1er utilisateur du ''Fauteuil Volant'' - ''Flying Armchair''.
Il s'éloignera avec son MMU à près d'une centaine de mètres de Challenger. Sans aucune attache le reliant à la navette spatiale.

Il sera également le responsable de la conception et du développement de IUS (Inertial Upper Stage) qui permet le largage des satellites depuis la soute de la navette.
Il a également été le responsable des procédures de mise en orbite d'Hubble, de la réparation du satellite Solar Max et des projets de la station Alpha qui deviendra par la suite ISS.
En 1990, il participe à la mission STS-31 qui voit la mise sur orbite du télescope spatial Hubble depuis la navette spatiale Discovery.
Après 2 vols spatiaux (STS-41B et STS-31), il quitte la NASA en 1990.
Interview réactualisée en 2010
How many years were you connected to the space program prior to your flight ?
5 1/2 years before my assignment to the backup crew of SKYLAB 1. 
17 1/2 years before actually flying on the Tenth Shuttle Flight, STS 41-B.
 How did you feel prior to the flight ?
Delighted to be both (1) actually realizing the opportunity to make a space flight, and (2) the prospective first-ever free-flying pilot of the Manned Maneuvering Unit (MMU).
 What kinds of sensations did you experienced during take-off ?
In the presence of the loud noise and strong vibrations of first stage flight, I was a bit apprehensive.
Intellectually, I knew what was happening, but it was difficult to actually perceive the situation using my own senses – similar to aircraft flight in instrument conditions.

What does weightlessness feel like, and what did you think about during the flight ?
"Weightlessness" is more the absence of feeling.
 One's body feels no pressure points, facilitating sleep when desired, and also is comfortable even in unusual attitudes / orientations.
 In particular, the "upside down" orientation is rather uncomfortable in a pressure suit in the (training) "water tank," but feels perfectly normal in the "real" weightlessness of orbital space.
I do not recall "thinking about" much during the flight other than the activity at hand, or planning for the next day. It was a very busy period.
What were some of the problems you encountered and how did you fixed them ?
Most of the problems encountered were not "fixed," but left behind as we moved on.
Examples: The solid rocket motors of the two PAM's (Payload Assist Modules) that boosted the WESTAR and PALAPA satellites each failed, about 20 seconds after ignition.
These two satellites were thus put into useless orbits, and later recovered by the STS 51-A mission later in 1984.
The Rendezvous Target Balloon exploded, instead of inflating, so we were unable to fully test the new Rendezvous RADAR system.
What did you eat, and did it taste real ?
We had pretty much the run-of-the-mill Shuttle foods, plus a "Trail Mix" (assorted nuts, candies, dried fruits, etc.) from a local vendor, which promptly renamed the product "Shuttle Mix," and proceeded to capitalize on its "flown" status.
I especially liked the freeze-dried "shrimp cocktail" item since the "cocktail sauce" contained a significant amount of horseradish, which had the effect of "clearing" my sinuses and enabling easier breathing.
Another favorite on my first flight, STS 41-B, was the radiation-stabilized beef steak.
It was delicious.
In contrast to "canned" beef, or beef "stew," the radiation stabilization process permitted retaining a "rare" level of cooking, which I prefer.
What did you feel prior to made the 1st MMU flight and what kinds of sensations have you had during this flight where you became the 1st man to use the MMU ?
As is well known, I spent almost 17 years working, part time, on maneuvering units of various sorts, including the SKYLAB M-509 Experiment, prior to launching on STS 41-B.
Consequently, I was both "over-trained," and highly confident that we had fully and correctly qualified the MMU's.
We actually had only one unexpected aspect of MMU flight – my actual combined (human + pressure suit + life support system + MMU) center of mass was about an inch vertically offset from the geometric center of MMU thrust.
Consequently, when attempting to simultaneously accelerate in the forward / backward directions and automatically "hold" an attitude, there was some rapid thruster cycling, which made an unexpected noise – but the system was working exactly as intended.
When venturing some distance away from the Shuttle Orbiter, however, I got quite cold – at one point I was shivering and my teeth were chattering.
The life support system had been designed to keep a hard-working individual comfortably cool – but the only real exertion in flying the MMU was using one's fingertips to manipulate the two hand controllers (one for translational accelerations, the other for rotational accelerations) !
What was re-entry like ?
Reentry was very smooth.
The "g" forces built up very slowly, never exceeding two "g's", and we only felt a light turbulence coming down through the jet stream at supersonic speeds.
Looking out the front windows early in reentry revealed an incandescent-hot vision – like looking into a red-hot/yellow-hot oven!
Looking out through the overhead windows showed that we were leaving a writhing, yellow-incandescent "tail" – a sort of "rope" trailing behind us.

Were you glad to be back on Earth, or did you feel you could have spent the rest of your life up there ?
I had mixed emotions.
I was both relieved that reentry had been fully successful (with the first Shuttle landing back at the Kennedy Space Center in the State of Florida) and aware that there would be a lot of additional training required and "jockeying for position" in order to return to space once again.
I would never entertain spending the rest of my life in space – Earth is too nice a place to live !

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