The View From L5

Link: http://www.moonsociety.org/2003-pcsn/16-L5view.html

Why NASA should put a RelaySat & Dedicated Moonscope at L5

Planetary Scientists and others have prioritized sampling missions to the South Pole Aitken Basin, some of which lies within the 60° slice of the Moon’s Farside around the east flank of the Moon. A relay satellite at L5, a stable Lagrange point at which gravitational forces of Earth and Moon are neutralized, would provide communications between Earth and ground probes and rovers within this area.

Objects at (L4) L5 forever (precede) trail the Moon in its orbit around Earth, “flying in formation” with the Moon at a 60° angle, as seen from Earth. The distance from (L4) L5 and the Moon is the same as that between Earth and the Moon, an average of 238,000 miles. So the advantage is not in proximity, but totally in the angle of perspective.

We also encourage NASA, as part of its outreach mission to both the public in general and to students in particular, to combine a small telescope with the communications relay in one package or bus.

The telescope could be smalll, with an 18 inch (45.5 cm) mirror, and dedicated to observing the Moon from this new perspective. The telescope would view the Eastern 2/3rds of nearside from a different angle, and would show the adjacent 1/3rd of Farside, not otherwise observable from Earth.

This telescope would be dedicated to amateur astronomers fascinated by the Moon and could switch between preprogrammed scans and views requested by amateur astronomers.

NASA would determine the size, shape, weight, and power constraints of the telescope as well as its telemetry interface. But design of the telescope would be the work of an amateur astronomy team, greatly increasing public interest.

There is precedent for such an approach. In 1984, a team based at Rensalleer Polytechnic Institute in New York State began work on designing an Amateur Space Telescope [AST] to fit in a NASA “getaway” special package. After the Challenger Accident in early 1986, the project was abandoned.

The design project was well developed at the time, specifying an 18 inch Ritchey-Chretien (version of a Cassegrain) Telescope design.

These AST plans could be dusted off, but the team could also decide on a clean slate design, given the advances in telescope design in the past two decades.

NASA would foot the bill for construction of the telescope and mating it to the relaysat package. NASA would also launch the combined package.

An “Amateur Lunar Flank Telescope” control center would be set up, possibly in Baltimore in connection with the control center for the Hubble Space Telescope. But other options should be looked at including a university-based center.

The object is not to discover new features either on the Nearside portion in the telescope’s view or in the adjacent Farside area. The purpose would be to increase public and youth interest in the Moon and support for Moon missions to come.

If the technological and outreach success of this project warranted, NASA could then launch a twin relaysat/telescope package to the L4 Lagrange area, extending the view available to amateur astronomers on Earth to more than 5/6ths* of the Moon’s surface.
[* The Moon’s libration or wobble would extend the views around both east and west limbs, or flanks to more than 60° into Farside, leaving only a small “orange peel slice” of farside out of reach]

The view from L5 would allow such interesting features as Mare Moscoviense and the major craters Tsiolkovsky, Mendeleev, Schrodinger and countless others to be seen from Earth for the first time, as well as to give face on views of several maria now seen only edge on along the Moon’s eastern Limb: M. Humboltianum, M. Marginis, M. Smythii, and M. Australe. We’d see Mare Crisium and Mare Anguis (dubbed “Angus Bay” by Greg Bennett) and M. Fecunditatis at the center of the hemisphere of the Moon visible from L5 instead of 60 degrees off to the right. Our view of them would be less distorted than in the view we now get from Earth.

A twin telescope at L4 would present a grand view of Mare Orientale which we now see only edge on, as well as some very rugged highland terrain on Farside. And, of course, the companion relay sat would extend communications to another 1/6th of the lunar surface. NASA must address the challenge of communicating with surface probes on the farside at any rate.

A simple and inexpensive third component of such a package could be a simple dust counter. Its purpose would be to characterize the “environment” around the L4 and L5 areas, which theory suspects will act as gravitational “Sargasso Seas” attracting dust and larger debris. Both areas have been proposed as locations in which we might someday construct Space Settlements as envisioned by Dr. gerard O’Neill, famous for his Island 1, Island 2, and Island 3 concepts. Indeed misty glows have been seen in the night sky in both of these areas by some amateur astronomers under ideal observing conditions.

For an Amateur Lunar Flank Telescope team to raise the money to build such instruments would be quite a challenge, with the odds of success against them. But with NASA footing the bill out of its mandated outreach program, would fit nicely into the Vision of Space Exploration program. The project might also energize SEDS chapters (Students for Space Exploration) and lead to the formation of new SEDS chapters.

We challenge and encourage NASA to consider such a student/NASA mission. We see this as a win-win proposal.