Fuel depots would allow NASA to mount moon missions without spending billions of dollars developing the gigantic Ares V rocket. Existing, less powerful rockets such as Boeing’s Delta IV or Lockheed Martin’s Atlas V would suffice.
Prior to each moon mission, fuel would be ferried to the orbiting depot by these or even smaller rockets operated by private companies. Competition for this work would drive down costs and spur development of more efficient launch vehicles, Goff argues. “Until we lower the cost of transportation to space, we’re never going to see serious off-world exploration,” he says.
On 30 July, the panel’s subcommittee on exploration beyond low-Earth orbit came out strongly in favour of creating fuel depots in space as a way to facilitate exploration beyond low-Earth orbit. At a public meeting of the panel in Cocoa Beach, Florida, the subcommittee proposed that depots be part of every space exploration scenario that the full committee puts forward in its final report.
Private companies would compete for the job of ferrying fuel to the orbiting depot
It remains to be seen whether the panel will back the idea in its final report, to be published at the end of August. “This panel is probably the best chance depots are going to have in the next 10 years to get actual NASA support and funding,” Goff says.
The committee reviewing NASA’s goals has outlined a scheme to send astronauts on progressively longer space trips – including dockings with asteroids and flybys of Venus – to prepare for an eventual landing on Mars.
One of the options the team proposed is called the “flexible path”, which Crawley also described as a “deep space” or “in space” option.
It would see astronauts sent on a series of progressively longer missions beyond low-Earth orbit. The first would fly by the moon. Later missions would include rendezvousing with one or more of the many asteroids on orbits that take them close to Earth. Asteroid missions would take several months each.
Later, astronauts could fly by Mars and Venus, and touch down on Mars’s 27-kilometre-wide moon Phobos. Each of these missions would take more than a year.
An advantage of the stepwise approach is that the difficult job of building landers and surface equipment could be deferred, since early missions would be restricted to flybys or rendezvousing with small objects that have negligible gravity – a process that would resemble docking with another spacecraft.
Although Crawley did not give a specific year by which the first human mission to an asteroid could occur, he said it could happen within six years of starting a project to accomplish this goal.
The other options on the subcommittee’s shortlist were:
• Mars first: Cancel the return to the moon and focus on sending humans to Mars instead.
• Lunar global: Have astronauts land in many different places on the moon’s surface, with the option of eventually building a lunar outpost, but focus on doing things there that really help prepare the way for human Mars missions. In one version of this option, hardware would be designed from the beginning to be used on Mars, with the moon missions serving to test it.
• Continue with the current plan, which aims to return astronauts to the moon by 2020 and eventually build a permanent lunar base. Meeting the 2020 deadline would presumably require an increase to NASA’s budget.
• Continue with the current plan, but keep within the budget currently expected for NASA by slowing the schedule.
• Continue with the current plan, but cancel the Ares I rocket designed to put a crew capsule in low-Earth orbit. In this case, NASA would build only the more powerful Ares V rocket, which is capable of sending crew and cargo to the moon.