Comments by "MRA" (@yassassin6425) on "" video.

  1. Good question. I know that the possibility of using a superconductive magnetic coil to create a very strong magnetic field near the leading edge of the vehicle to deflect plasma is currently being researched. This would be much lighter than an ablative heat shield and would eliminate the cost of reapplication in the case of craft such as Crew Dragon. However there are a myriad of challenges associated with the development of this, chiefly calculating changes to the trajectory of a vehicle, because the air will be deflected away much more than with current heat shield technology. Also, the ionised gases surrounding a capsule using a magnetic heat shield would prevent the use of radio signals for telemetry data.
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  2. Reentry is basically an energy management equation. In the case of the shuttle, it was about shedding it at precisely the right rate to reach the landing site and in one piece. If the angle is too acute then the vessel will burn up, too shallow as you suggest and even apollo/soyuz capsules are lifting bodies and will bounce off the atmosphere and into space like a pebble skimming across the surface of a pond. Since orbital velocity is in the region of 17,500 mph - depending on orbit, it would take a huge amount of energy to shed this and so the atmosphere is used as a brake. Crewed space vehicles must therefore be slowed to subsonic speeds before parachutes or air brakes may be deployed. Such vehicles have kinetic energies typically between 50 and 1,800 megajoules, and atmospheric dissipation is the only way of expending the kinetic energy. The amount of rocket fuel required to slow the vehicle would be almost equivalent to the amount used to accelerate it into orbit. This has to be performed at precisely the right angle although high G ballistic reentries in which the only forces are gravity and drag are still an emergency contingency.
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  3. Good question. I know that the possibility of using a superconductive magnetic coil to create a very strong magnetic field near the leading edge of the vehicle to deflect plasma is currently being researched. This would be much lighter than an ablative heat shield and would eliminate the cost of reapplication in the case of craft such as Crew Dragon. However there are a myriad of challenges associated with the development of this, chiefly calculating changes to the trajectory of a vehicle, because the air will be deflected away much more than with current heat shield technology. Also, the ionised gases surrounding a capsule using a magnetic heat shield would prevent the use of radio signals for telemetry data.
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