Chair Force Engineer

Tuesday, July 08, 2008

Ticket to the Moon

Elon Musk, CEO of SpaceX, has provocatively declared that an eventual flight around the moon would cost $80 million. I assume he means $80 million per seat, which is four times the rate of an ISS trip on a Russian Soyuz.

Mr. Coppinger complains that passengers in the cicrumlunar "Dragon" will be cramped. They'll need a habitation module and an earth departure stage, or so he claims. While SpaceX's Dragon capsule can carry up to seven people, it's likely that some seats would be removed for the lunar voyage to reduce mass and/or provide more habitable volume. It is likely that a circumlunar version of F9 Heavy would need a restartable upper stage to perform the mission, unless the current second stage can restart, and if it has enough propellant left over once the capsule has achieved orbit.

The plan to launch a Dragon around the moon using a Falcon IX heavy has a lot of merit. Unfortunately, I'm skeptical whether Falcon IX Heavy is capable of the 27 ton payloads that are promised. That's similar in performance to the postulated Atlas V Heavy. Unfortunately, Falcon IX has less energetic engines on both stages compared to Atlas V. The gas-generator Merlin has a vacuum Isp around 309 seconds, while the staged-combustion RD-180 has an Isp of 331. The upper stage comparison is between the kerosene-burning Merlin and the hydrogen-burning RL-10A-4A; there's no contest betweenthe two upper-stages performance-wise. Until a Falcon IX flies, it's hard to say whether it will live up to expectations.

Still, Elon Musk's announcement should serve as testing the waters on whether there's a commercial demand for lunar exploration. While the lunar trip might only appeal to eccentric billionaires at first, it's the first step towards an entire lunar exploration industry.

EDIT: After re-reading the Rob Coppinger piece, it appears that the quoted $80 mil figure is for the entire mission, and all seven seats will be utilized. Such a boast does not pass the sniff test. But a four-crew mission with each ticket costing $80 mil seems to be a more credible approach.