With all of the plans various nations have for resuming manned exploration of Earth’s moon, has any mention been made of manned exploration of the moon’s far side?
Specifically, I’d like to know about plans to build large radio telescopes there, (as scientists have talked about in the past.)
It seems that would be a really exciting place to be stationed for radio astronomers.
A lot of these plans, especially Russian and Chinese, are more propaganda than anything real. The US might be going back to the moon, but I doubt the mission will be adventurous like planting a telescope on the far side, but it will be a very safe PR move for NASA.
That said, we dont need men on the far-side to plant a telescope. We can drop one off with robotics.
Radiotelescopes vary greatly in size. A small one would not need to use the moon surface for structural mounting. In fact, Japan has orbited a small radiotelescope. One like that could be placed in interplanetary space, like the James Webb Space Telescope will be.
I highly doubt a radiotelescope big enough to require mounting to the moon’s surface could be built by robots. It’d be a major construction project requiring site preparation, precise surveying and alignment, etc.
A small start on doing such has been made:
Of course, this argues against human labor construction of a radio telescope on the surface of the Moon (face side or far side), too. Even the fairly minor tasks that manned missions have performed on the Lunar surface (erecting equipment, exploration on foot and in the Lunar Rover) have turned out to be far more problematic and risky than anticipated. In fact, there is very little reason for establishing a manned Lunar base except as a practice exercise for constructing habitats and structures on other celestial bodies. And of course, bragging rights. Compared to the costs and hazards of a manned Lunar presence, robotic exploration makes substantially more sense for the foreseeable future from any practical standpoint, though there is a persistent logic in pursuing some level of limited manned space program if just to maintain current understanding of the problems and solutions and to incrementally improve the state of the art until such time that life support and propulsion technology make interplanetary transits a realistic possibility.
To address the unstated assumption of the o.p., solar-orbiting telescope (or one located in the metastable L2 libration point) makes a lot more sense; it doesn’t have to be soft-landed down into a gravity well at great expense and risk, it won’t be subject to or have to be isolated from any of the seismic events endemic to any ground-based telescope, it can be pointed in any direction necessary and held in orientation indefinitely by the use of precisely controllable reaction wheels without having to account for the rotation of a planetary body, and you won’t have to deal with the corrosive and tribological effects of atmosphere and dust contamination. The few deficiencies that apply to space telescopes (evaporation of volatile lubricants, unmitigated exposure to ionizing radiation, orbital FOD) also apply to a Lunar telescope.
Stranger
What advantage would a moon-mounted telescope have over an orbiting one like Hubble? They would both have the significant advantage of not having to peer through the Earth’s atmosphere, and I suppose the moon telescope would be slightly closer to what it was looking at, but…with technology advancing as it is, can’t we just drop a newer version of Hubble into orbit around the Earth with a bigger, better mirror and computers?
The advantage for this scenario to me would be that it is closer to the Earth than a moon-based one, and therefore would be more readily accessible for maintenance via spaceflights, and also wouldn’t the command control signals be faster than on the dark side of the moon, since it never faces the Earth?
Fight my ignorance, I am very interested in observing the cosmos for there is so much to learn.
I don’t know if there’s any advantage to having a large optical telescope on the moon, although I guess it would be easier to build larger on a surface. However, a radio telescope would work better on the far side of the moon, because it wouldn’t have to deal with all the radio chatter from terrestrial sources.
To amplify on that point, the reason is that the bulk of the moon will block radio signals from Earth.
Which brings me to a question - how would we get the data back to Earth from the LunaFarSide-o-Scope™? Presumably we’d need to build a few extra relay transmitters to bring data round to the “front” of the moon and beam it back to us.
That’s true. As Stranger on a Train has discussed above, the situation of a lunar telescope and an orbiting one are pretty similar. The one on the moon has the disadvantages of being subject to lunar gravity, dust and magnetic fields on the surface, and the hassle of landing everything on the moon when you can just float it in space, among other things. The advantage, though, is that you can make a very large array with very long baselines – potentially almost the diameter of the moon itself. It can also be shaded from Earth’s radio noise (by the moon).
This advantage is completely trivial given the distances to the objects being observed.
For various reasons (see my ‘anonymous’ post here), it’s not practical to launch an upgraded Hubble. Instead, the partner agencies (NASA, ESA, CSA) are developing a completely new design to go into a Lagrange orbit out beyond the moon. This is the James Webb Space Telescope, to be launched in 2013.
Radio signals cannot, in general, get to the surface of the moon’s far side directly from Earth at all; they would have to be relayed by some kind of lunar communications satellites. The delay is probably negligible in the event such a satellite is visible to both the Earth and the telescope; if there are times when no satellite is available, the delays might then be significant (ie, waiting for visibility again).
I should point out, as well, that the design of a radio telescope is very different from that of an optical telescope. Optical scopes use lenses, mirrors, and camera elements; radio telescopes use tremendous arrays of antennas. Because of the wavelengths involved, a radio telescope needs to be much larger (in general), but is more tolerant to misalignment and positioning errors. For reference, Hubble has a mirror of 2.4 m diameter; JWST will have a segmented 6.6 m mirror array. The VLA radio telescope (in New Mexico) has antennas of 25 m, spread out over an area of 36 km diameter.
An optical telescope on the moon has little advantage over one in orbit; it has to deal with dust, gravity, and rotation of its base, as well as moonquakes which can shake it. These last are a problem because these telescopes need fine pointing control, and have sensitive optical elements.
The radio telescope could probably accept these vibrations a little more, and benefit from the large area over which to spread the antennas. But you could also fly spacecraft in formation, an approach which is the subject of current study.
The moon is probably a bad place for infrared telescopes, since the moon itself is warmer than many of the distant objects being studied with these. This noise would, I suspect, make observations very difficult. Recently-launched infrared observatories already have to cool their detectors down to as low as a tenth of a degree above absolute zero; the moon is a lot warmer than that.
Gamma ray observatories need to be pointed rapidly, because many of the interesting gamma sources are short-lived. This is easier to do in free spaceflight, when you don’t have a big ball of rock obscuring half of your field of view.
You could have a satellite that picks up data from the telescope on one side of its orbit and transmits back to earth on the other side.
