TR: I understand that Orion will have a new type of heat shield for reentry into Earth’s atmosphere.
PM: The idea is pretty much the same as with Apollo, but there will be a new design and new materials that provide more robust protection. That’s important because with vehicles coming back from the Moon, or particularly from Mars, the reentry velocities are going to be a lot higher [than with spacecraft in low-Earth orbit]. We are looking at heat-shield materials like PICA [phenolic impregnated carbon ablator] and SLA [a cork-based ablative material] that Lockheed has proven on the Genesis and Stardust deep-space sample return missions.
Another thing that’s going to be new is “skip reentry,” which we are going to be doing routinely. That’s where you bounce off the atmosphere and come back in again, which gives you the ability to touch down on land, as opposed to the Apollo landings in the ocean. That provides an extra measure of safety and enhances the reusability of the system. Of course, we’re also looking at upgraded landing-impact systems. You still come down on parachutes, like Apollo did, then you deploy airbags or fire retrorockets, similar to what the Russian Soyuz vehicle does, to slow down the vehicle for a safe landing.
TR: What will conditions be like inside the crew module?
PM: Apollo could carry only three people, and they had very tight living conditions. The Orion crew module will have twice the volume: 361 cubic feet per crew member. Four crew can go back and forth to the Moon, and on flights to the International Space Station we could accommodate up to six crew. Also, the crew module will be able to stay in orbit around the Moon in a fully autonomous mode, so all four crew members could go down to the surface, for potentially long-duration stays.
TR: For Apollo, NASA designed an abort system to carry the command module away from the Saturn V rocket in the event of a launch emergency. Such an abort system might have saved the Challenger astronauts, but unfortunately the Space Shuttle doesn’t have one. What’s being planned for Orion?
PM: It’s the same kind of idea as with Apollo. One of the particular advantages of the capsule configuration over the Space Shuttle is the fact that we aren’t side-mounted. On the Shuttle, both the solid rocket boosters and the external fuel tank are right up against the belly of the vehicle, and there is no way to separate the crew from those in an emergency. Orion will sit on top of the Ares I launch vehicle in the same fashion as Apollo, so that if there’s any kind of issue with the rocket below, the advanced launch abort rockets on the tower above the crew module are fully capable of accelerating away from the Ares and getting the crew into a safe situation, with parachutes for landing.
TR: The old mechanical cockpit systems in the Space Shuttle were recently replaced with a modern “glass cockpit” design, with fully electronic displays and controls. I assume that technology will go into Orion as well?
PM: The avionics systems on board are going to be light-years ahead of where Apollo was. Not only will we have what you called the glass cockpit, but the other key element is “dual fault tolerance.” That means that with the critical systems being built into Orion, you could have two failures in the same system and still fly safely. The system that our teammate Honeywell is working on is based on the avionics architecture of the Boeing 787, which is also dual-fault tolerant. The systems constantly monitor one another, and if one system has a problem, another one automatically takes over. It adds some additional weight and complexity to the vehicle, but it provides a much greater margin of safety on these very dangerous space missions.