“Return to the Moon”, the Bush Administration’s road map to space, may be more of a cul-de-sac. This is the contention of The Planetary Society in an article by Robert Farquhat in the March / April 2008 edition of their magazine Planetary Report.
NASA has focused on the Moon base as its next logical step, and spelled this out in some detail in its Vision for Space Exploration (VSE). Proponents of the Moon base have several objectives:
1. Expanded human exploration of the Moon.
2. Establish large telescopes.
3. Test technologies and techniques to be used on Mars.
However, lunar exploration on a large scale can be accomplished much faster and cheaper with robotic missions. While a large radio observatory on the far side of the Moon may make sense, placing large telescopes on the dusty moon does not. Performance, accessibility and cost all favor space based systems. Lastly, systems designed for the airless Moon will not be used on Mars.
Remember to keep your eyes on the prize: Mars and Beyond. Farquhar, of the Johns Hopkins University, has said:
“I think that if we get stuck on the cul-de-sac of going to the Moon, I don’t see us going anywhere else for the next 75 to 100 years, because that’s such a huge program…”
Farquhar is leading a follow-up to a study issued by the International Academy of Astronautics in 2004 entitled “The next Steps in Exploring Deep Space”. This study identified four destinatins: Sun-Earth Libration Point L2 (SEL2), the Moon, Near-Earth Objects (NEO’s), and the planet Mars. SEL2 is 1.5 million km beyond the Earth, in a line with the Sun.
Now, what’s the point of L2, we should ask. Joseph Veverka, a professor of astronomy at Cornell University, who is also involved in the IAA study, has said:
“There are at least 19 or 20 missions over the next 20 or 30 years that want to go to the L2 point.”
Among these missions is the James Webb Space Telescope, the successor to the Hubble Space Telescope. SEL2 capability would mean that servicing the James Webb Space Telescope, or its successors, could be done on a routine basis, without developing an expensive robotic servicing vehicle. Or, abandoning the investment if something breaks. The use of libration points was initiated long ago by the International Sun-Earth Explorer-3 (ISEE-3). ISEE-3 took up residence on 20 November 1978 at L1 (between the Sun and the Earth).
As noted in an article in The Space Review:
The alternative Farquhar and his international team of colleagues are investigating involves bypassing the Moon for more distant destinations. Instead, human missions would initially go to the Sun-Earth L2 (SEL2) point. That location would serve as a staging point for more distant expeditions, initially to NEOs and, later, to the Martian moon Phobos. Eventually the architecture would support human missions to the surface of Mars, just as such missions are an ultimate long-term goal of the VSE.
So what is involved with this approach. The IAA study proposed three initial steps:
1. Establish a staging node at L2 for human missions beyond the Earth-Moon system.
2. A human mission to a near-Earth asteroid.
3. A human mission to one of the Martian moons.
These are the organizing principals of the IAA study. These milestones each takes us toward Mars. And they generate a lot more science than the Moon base.
The first piece of hardware is the Deep Space Shuttle (DSS). This involves a service module capable of supporting up to four crew for 50 days, a detachable re-entry vehicle such as NASA’s Crew Exploration Vehicle (CEV), which is currently in development, and a chemical propulsion system. The total delta-V required for the low-Earth orbit (LEO) to L2 and back is less than 5 kps, and the delta-V for the trip to L2 is almost the same as to low lunar orbit.
The second piece of hardware is the Interplanetary Transfer Vehicle (ITV). The components include a crew module for five or six members capable of sustaining a mission for up to three years, a propulsion module, and a detachable re-entry vehicle (CEV). ITV would be assembled at L2, and maintained there, empty.
The mission scenario involves a small (less than 50 meters per second) adjustment out of L2 into an elliptical Earth orbit. The DSS would transfer the crew and supplies from LEO to the ITV, which would execute an Earth-escape maneuver. The mission (NEO, asteroids, or the moons of Mars) would be conducted and the ITV would return the its elliptical orbit. The crew would return to Earth, and the ITV would return to L2.
Farquhat closes the article with this note:
If plans for a Moon base don’t stop us in our tracks, the path ahead can lead human explorers to an asteroid, to a Martian moon, and then to Mars.
