Moon Miners' Manifesto

#10 November 1987

Farside

FARSIDE

Part II. The Ideal Site for Front-Line Astronomy in the 21st Century

By Peter Kokh

A popular theme of science fiction has long been the idea of using the Moon, and particularly the lunar "farside", as a platform for astronomical research. The advantages the Moon offers over today's orbital satellite astronomy are considerable:

1. shielding over 50% of all vectors ( 2 pi steradians ), and with it, halved exposure and vulnerability to cosmic rays, flares, and micrometeorites;
2. greatly reduced radiation coming from particles trapped in Earth's magnetosphere and Van Allen Belts;
3. vastly reduced vulnerability to the swiftly multiplying trash-belt of cavalierly discarded space junk, a trend which, if not soon reversed, will eventually render LEO orbits unusable;
4. a rotation rate 400-500 times slower ( 0.5 degrees or 33 arcminutes per hour versus 240 degrees for the typical LEO-sited facility, and with it the possibility of long exposure times of up to two weeks or more, extreme stability, and long integration times;
5. ease of access for maintenance and changeout of equipment;
6. low 1/6th g which will be a mechanical plus in comparison to both 0g and 1g and which will allow very large instruments and which also serves to scavenge dust out of the environment very rapidly ( not so in the "Sargasso sea" environments of LEO, L4, and L5. )

These advantages over LEO facilities are available anywhere on the Moon. Even for radio astronomy, the Earth presents a far smaller cross-section and can conceivably be baffled out-of-sight, especially since Earth's position in any nearside sky remains fixed within libration limits of a few degrees.

Radio astronomy has been at the forefront of astronomical research for more than two decades. At first very crude in its resolving power, integrating arrays of radio telescopes can now achieve angular resolution and detail that optical astronomers can only drool over. But the problem arises with interference from man-made radio and TV signals which make for poor listening even as Earth's thermally shaky atmosphere makes for poor seeing for optical instruments. The idea, long a favorite in science fiction, has been to put radio telescopes beyond reach of such interference on the far side of the Moon. Here we can best listen to the "music of the spheres" from natural astrophysical processes and, some hope, from intelligent species, if there are any out there trying to make their presence known.

Not just anywhere on Farside will do, however. Not only should such an installation ( let's call it FARAF, Farside Advanced Radio Astronomy Facility ) be closer to the equator than the lunar poles, so as to cover as much as possible of both celestial hemispheres, but it should be in the shadow, not just of Earth-direct transmissions but of indirect relayed transmissions from the L4 and L5 Lagrange areas, 60 degrees ahead and behind the Moon respectively in its orbit about the Earth, where the Moon's version of synchronous communications satellites will be placed.

Line-of-sight exposure to L4 and L5 encroaches 60 degrees or more ( if "halo"" orbits are used ) on each flank of Farside thus ruling out such otherwise ideal sites as Tsiolkovsky crater, Mare Orientalis, and Mare Moscoviensis. Rather, only a central "orange-slice" between 155 E and 155 W ought to be considered, restricting us to 25 degrees either side of the central Farside meridian, 180 degrees. Moreover, a treaty or convention will be needed to prohibit the use of the L2 Lagrangian position behind the Moon for anything but intermittent tight-beam transmissions on a non-casual emergency basis only. Laser-based communications relays via L2 to sundry Farside points are a possible substitute. If such alternative communications systems cannot be developed, it may be necessary to make Deep Farside off-limits to settlers except at, around, and in support of FARAF.

We have already mentioned some mare/diluvium-floored Farside locations that must be ruled out. Highland type sites abound, of course, and the ivory-tower ideal site at 0 degrees ( the equator) and 180 degrees E-W is on highland terrain. However, this would limit us to highland-sourced building materials and rougher topography than would be available at a highland/mare "coastal" or "near-shore" site which would offer the advantages of both kinds of soil and terrain. Further, mare-like areas will be vastly superior for such extended installations as a Socorro ( NM ) type Very Large Array or even for its design-archetype, the "Cyclops" Array.

Unfortunately, there is no such mare / coastal site anywhere near dead-center Farside. The site I would like to suggest is northeastern Mare Ingenii ( variously translated as the Sea of Engineers or the Sea of Ingenuity ) centered about 168 E and 32 S. While this location is further south than one might wish, it will still allow full coverage of the entire Milky Way and such important nearby galaxies as M31 ( Andromeda ) and M33 ( Triangulum ). Bear in mind that, on the Moon, the apparent celestial equator will more nearly coincide with the ecliptic -- the plane of the sun and path of the major planets.

Mare Ingenii is incompletely and thinly covered over much of its expanse with mare lava sheets. The best flooding conveniently occurs in the large ( 70 mi, 112 km ) Thomson Crater in the ENE part of the Mare Ingenii basin. This is surely the ideal site for the next generation VLA ( Very Large Array ), a "Y"-shaped array of movable, tracked, steerable radio telescope dishes that can provide significant resolving power, working in concert. Ancillary smaller outlying installations for further image integration over longer baselines could be placed at convenient Farside sites outside our "orange-slice" preserve. ( It goes without saying that a competing free space array anchored in L4 and L5 with a baseline of about 400,000 miles ( 643E3 km ), should also be built and teleoperated from central Nearside. )

On the north crater rim of Thomson are a number of small deep craters that might prove suitable for a large unsteerable Arecibo-like dish, appropriately scaled up as far as the lesser lunar gravity will allow. Nor need our Mare Ingenii-Thomson site be restricted to radio astronomy. Dedicated optical/infrared observatories concentrating full-time exclusively on the two Magellanic Clouds, the major companion satellite galaxies of our Milky Way, lying at ( LMC ) and near ( SMC ) the lunar celestial south pole and always above the horizon from our proposed FARAF site, are a logical adjunct.

What about the supporting settlement itself? Not only will astronomers and technicians be needed, but also support personnel to grow food and maintain the life-support systems, in short a whole community of eventually some hundreds. And what about a name for the place? Thomson City? Or tired, stuffy names related to the history of radio astronomy or SETI such as Marconi, Sagan, Jansky, Spielberg, or New Socorro? Personally, I'd like to see something more suggestive of the special vocation of this unique settlement such as Sussuri ( Latin for 'whispers', i.e. of the stars ) or simply Stellarum ( Latin: 'of the stars' ).

Sussuri would have a very distinctive ambience. Earth would be out of sight and out of mind. The sunless fortnights would be dominated by the Milky Way in spectacular unrivaled brilliance. The whole mentality would be outward-oriented, astro-empathic, in tune with the stars ( and any supposed intelligent species circling them ). A major hobby will be brainstorming end-runs around the restrictions imposed by the speed of light and the shortness of human lifetimes. The psychological distance of Sussuri from Earth and its flesh-pot distractions will be far greater than any physical quarter million miles. For some, not all, of course, Sussuri could be a stimulating place to live out one's years.

--- Peter Kokh

Contents of this issue of Moon Miners' Manifesto