As I mentioned in the previous post, the book keeps getting delayed because events occur that simply beg to be incorporated. One that was hanging me up but is no longer because I’ve incorporated it, is Inspiration Mars. Here is one of the relevant sections, as a further tease for the book:
…consider the case of the Inspiration Mars plan. In order to get the crew and hardware needed to perform the mission into orbit, they will need to get a launch license from the FAA-AST (and probably more than one, since it seems unlikely that the mission will be feasible with a single launch, even with Falcon Heavy). That license will be issued after reviewing it to ensure that it is not deleterious to the security or national interest of the US, or a danger to (among other things) the environment or public safety. To what degree should they have a legitimate concern with the safety of the mission participants themselves, given that this will be a non-government mission?
On ascent, none at all. Entry, however, could be more problematic. This vehicle will be the largest, fastest artificial object to ever return to earth, at over fourteen kilometers per second (escape velocity is a little over eleven). Energy goes up directly with mass, and as the square of the velocity, so it will have about sixty percent more energy than an equivalent mass coming back from the moon (e.g., an Apollo capsule). If, instead of skimming the top of the atmosphere to gradually slow1, it comes in at a very high angle, or even vertically – that is, it targets the center of the earth rather than the limb (i.e., edge), it could do as much or more damage than a meteoroid (like the one that recently exploded high over Chelyabinsk in Russia, which would have destroyed the city had it released the energy at a lower altitude).
Presumably, it won’t be just the capsule that enters, but the expandable module and trans-Mars Insertion stage as well, though they’ll have to separate from them first in order to allow a safe capsule entry (the capsule will presumably only be designed to enter itself, not the whole deep-space assembly). If it does enter (that is, they only do a small separation maneuver to build up a little distance between them beforehand) they would burn up in the upper atmosphere, though it’s possible that some parts of them might make it to the ground. The other option would be to separate while on a trajectory that misses the earth, and then do a correction burn of the capsule to have it enter properly, leaving the rest to become one or more new artificial near-earth objects orbiting the sun. This would involve a trade-off between the risks of pieces of them hitting the ground and those of creating new extraterrestrial navigation hazards, and the risk of killing the crew if they fail to perform the final entry maneuver, sending them off for another solo journey around the sun without sufficient supplies and the loss of much of their radiation protection. From a crew-safety standpoint, aiming for a good entry interface from millions of miles out, minimizing the time that they have to spend in the more-cramped capsule, would obviously be preferable, but it increases the risk to everyone else, even if by a minuscule amount.
As noted in the previous chapter, the safety of the crew for this project is a primary mission goal. If they don’t survive, the mission will have failed, with little to show for it except perhaps lessons learned for future attempts. The crew is an essential element for hardware success, in that they must maintain the life-support and other equipment necessary to get to Mars and back. The question is: will they also be necessary to ensure a safe entry? That is, will they be responsible for the adjustment burns needed to get the correct entry interface? Or will it be done from the ground?
If they are responsible for maneuvering, then the FAA will have a legitimate interest in ensuring that they are alive and healthy at least through the final correction burn to ensure an entry that poses no risk to those on the ground. If not, then the agency has no current statutory authority to be concerned with whether or not they return dead or alive, any more than they are concerned with whether or not a commercial payload gets to orbit. That is, (and to repeat) their sole job with regard to safety is public safety, not mission assurance.
Now, we have a wealth of decades of demonstrated experience since the early sixties with performing very precise and accurate planetary maneuvers with unmanned probes2, so in fact there would be no reason to put the crew in the loop, and this would be a good reason not to do so, if the project’s planners want to minimize potential issues with their launch licensing in that regard. If the crew is not mission critical for entry, then (at least prior to the current planned end of the moratorium in October, 2015, and if the prospects for extending the moratorium look poor, it would behoove them to get a launch license before that date), the FAA would have no legitimate concern with their safety. It would be well not to establish a precedent in which they did.
1. The current mission baseline is to make two passes, reducing it to seven kilometers per second for each pass with a several-day earth orbit in between them. This would reduce the heating energy per pass by seventy-five percent.
2. A notable exception was the loss of the Mars Climate Orbiter in 1999, when it did a “controlled flight into terrain,” striking the planet instead of orbiting it, due to a confusion between English and metric units. Its trajectory into the planet was, however, quite precise. It should be a valuable lesson for Inspiration Mars.