Beyond the Moon and Mars

Musk has been quoted saying that the Dragon capsule can be used to explore almost any world in the solar system: “With Dragon launched on a Falcon Heavy, it can go pretty much anywhere in the solar system, because that’s a heck of a big rocket...Dragon 2 is capable of transporting scientific payloads to anywhere in the solar system, with a liquid or solid surface, with or without an atmosphere. So Dragon is really a crew transport and science delivery platform...Dragon, with the heat shield, parachutes and propulsive landing capability, is able to land on a planet that has higher entry heating, like Mars. It can also land on the Moon, or potentially conduct a Europa mission.”

Musk’s claim appears to touch on three separate issues. The first is whether the Falcon Heavy could propel a Dragon spacecraft to any location in the solar system. The answer likely is yes. For our moon, Mars, and Venus, the launcher will be able to send the Dragon directly to these worlds. If the Falcon Heavy cannot send a Dragon directly to Mercury or the outer planets, it certainly could launch it on a trajectory that would use Venus and/or Earth gravity assists to provide the additional velocity needed.

The second issue is whether the Dragon could land on these more distant worlds, which breaks into two parts. The first is how the Dragon capsule would kill the high approach velocity when it reaches its destination. The atmospheres of Mars, Venus, and Titan can kill much of the speed. It’s less clear to me whether the Dragon spacecraft would carry enough fuel to first brake into, say, Jovian orbit and then kill the remaining velocity to land on Europa. (A direct landing on Europa without entering Jovian orbit also would need to kill a lot of speed.) Musk’s statements suggest it could, but for now we lack details.

The third issue is whether the Dragon spacecraft could deal with the special environmental issues at various worlds. The moon and Mars are reasonably straightforward challenges both because of their proximity and their comparatively (for planetary destinations) benign environments. By contrast, while the Mercurian poles are cool, the spacecraft would need to deal with intense solar heating on the way to this world. The surface of Venus is intensely hot and has a crushing atmospheric surface pressure. Jupiter’s moon Europa sits deep within an intense, electronics frying, radiation belt. Titan’s surface is as bitterly cold as Venus’ is broiling. Landing on a small asteroid or comet may require special adaptations such as harpoons to hold the capsule on the surface. Traveling to any world beyond Jupiter will require a radioisotope generator for power (Saturn might be an exception).

It is possible to design spacecraft to handle any of these challenges. Missions have been proposed to land on each of these worlds, but using custom designs that take into account the unique challenges of each environments. Would it be cost effective to modify the Dragon spacecraft to handle the challenges of any of these worlds, or more cost effective to design a custom spacecraft?

There’s also the question of whether a prior scouting mission would be needed. For the moon and for high priority locations on Mars, existing high resolution images would allow mission planners to identify precise locations of safe terrain within otherwise rugged but scientifically interesting terrains. The same will be true for selected sites on Europa following NASA’s planned Europa Multiple Flyby mission. What about a world with only coarse resolution mapping or none at all?