Science: Telescopes on the Far Side of the Moon
Tuesday, February 26, 2008; 11:00 AM
Since the beginning of the space age, astromers have dreamed of putting telescopes and other instruments on the far side of the moon, and now with NASA planning to send astronauts back to the moon sometime after 2019, those dreams of a radio telescope looking out through the galaxies from the protected side of the moon have been revived.
Join Washington Post science writer Marc Kaufman on Tuesday, Feb. 26 at 11 a.m. ET for a discussion about the latest news, which he reports in the Monday Science Page story.
A transcript follows.
Marc Kaufman: Good morning, folks. We're talking today about some NASA-funded preliminary plans to place arrays of radio antennas on the far side of the moon. This is a plan astronomers have dreamed about for decades because it would allow them to use radio telescopes to look very, very far into the past of the universe. If the arrays of antennas can be placed on the far side of the moon, then the ever-growing radio interference created by us on Earth would be blocked out and the secrets of the early universe can be much more intimately explored.
If this were to happen, it would be well in the future. But big projects like this take time and have to start small.
Farragut Square, D.C.: Mr. Kaufman:
Fascinating project you've written about; thank you. Forgive me if I'm overlooking this, but how would the instruments on the moon's far side send their data back to earth? And how would we send any modifying signals to the instruments? Maybe I slept through that lecture back in the '80s....
Marc Kaufman: No clear answer yet to your question. The two different proposals -- which may in time be joined -- call for transmitting information by laser or through other means to either a receiving computer station on the moon or to a circling satellite. In either case, info would be then transmitted back to Earth. Because the amount of data coming in will be enormous -- with hundreds or thousands of dipole radio antennas set up in large arrays -- receiving, computing and analyzing the information will be a huge and daunting task. Researchers are still in the early stages of figuring it out, I believe.
St. Paul, Minn.: Would it be possible to put a satellite telescope in stationary orbit above the far side? (I don't know what to call the orbit - maybe lunar-synchronous?)
If so, wouldn't this be a bit easier to do than to have one on the lunar surface?
Marc Kaufman: The researchers tell me that having the arrays on the lunar surface would greatly enhance their ability to receive data. They also say that it doesnt seem feasible to have a substantial array of radio antenna circling the moon, and that surface-based makes most sense.
Washington, D.C.: Thanks for writing this article, Marc. It highlights one of the reasons we should be going back to the Moon. I'm wondering though, why the people designing these 'scopes believe it will be so expensive and take so long. We know how to build radio telescopes and we know how to build space telescopes - why is this such a stretch? And would NASA astronauts sent back to the Moon do the construction work or would the telescopes be "dropped" into place like one of the Mars Exploration Rovers (plug and play, so to speak)? Or are we smart enough now to build robots that could assemble the telescopes for us?
Marc Kaufman: A lot of good questions here. That $1 billion figure is obviously imprecise, but it does show the scale of what's involved. I believe the issue of how to receive, transmit and analyze the data is both daunting and costly, and can perhaps explain some of the pricetag.
As mentioned earlier, one reason why NASA likes this idea is that it would indeed involve lunar-based astronauts in a major scientific project. A first stage might involve planting a pre-assembled array of antennas near the lunar South Pole, where it could get some very faraway signals, but where it could also measure coronal mass ejections from our sun and other aspects of space weather.
As for how arrays might ultimately be placed on the far side of the moon, it might involve astronauts, it might involve pop-open antenna being planned by the MIT group, it might involve automated rovers. This is clearly where real science and science fiction begin to meet.
Eden, N.C.: Hi, Marc, just a quick question for you here: Why does everything NASA plan to do require years for its realization? Seems to me 2019 is an awfully long time just to get back to a place we've already been before...
Marc Kaufman: Here is the $64,000 question: Why does it all take so long. A number of reasons, including limited NASA funds, the large number of tasks NASA has been given, the need to develop new technologies, and the sheer difficulty of some of the projects. While we have indeed visited the moon, the current plans call for returning with a goal of setting up small settlements for long-term stays, and that would apparently be quite challenging to make work. Some people very interested in space and space exploration say that returning to the moon would be a costly and time-consuming distraction, and that NASA should instead be thinking of heading to nearby asteroids or to Mars.
Tehran: Why on the far side of the moon? is there any scientific reason? what's that?
Marc Kaufman: The far side of the moon is protected from the jumble of radio interference created on Earth - everything from radio stations to garage-door openers to television transmission satellites. That allows for a much deeper probe into space and time. The far side of the moon -- which, of course, is not a "dark side" but rather the side that never faces us because it is tidally locked into place -- is the quietest part of the inner solar system for radio astronomy, I was told.
In addition, part of our atmosphere -- the ionosphere -- interferes with radio waves, and so limits the precision and and breadth of radio astronomy from Earth. The moon doesn't have anything like the ionosphere.
Lanham, Md.: I guess you will have to put a satellite in lunar synchronous orbit to serve as a relay since radio transmission between the far side of the moon and earth is not possible?
What happens when the far side is facing the sun?
Marc Kaufman: You are correct that there would most likely have to be a relay satellite.
As to the periods when the far side of the moon faces the sun, it may well be that the antennas would be swamped with radio waves from the sun, and so couldn't look deeply into space at those times. But measuring and better understanding the sun is another goal of the proposed mission.
St. Paul, Minn.: From the article, it sounds like possibly this would be done in conjunction with a permanently occupied moon base.
Would such a base be a requirement of the telescope? I assume people would not be stationed right at the site of the telescope.
Also, is there any talk of other types of telescopes on the far side?
Marc Kaufman: I'm unaware of astronomy proposals for the lunar far side other than for the radio telescope, which would have unique advantages there.
And yes, as of now it seems that a radio telescope system on the far side of the moon would need human attention and human help in setting it up. And while humans would not set up a permanent moon base on the far side, current plans are for a base near the lunar South Pole, and the initial prototype radio antenna array would be laid out there. Much, however, could change before this ever becomes a reality.
Fairfax, Va.: If Obama wins the presidency can NASA expect financial set backs? I remember hearing that he wasn't too keen on the idea of putting serious funding into NASA and the moon mission(s)... which brings on a second question, are we talking about one moon mission to get all this accomplished, or several like APOLLO did?
Marc Kaufman: While NASA, space and exploration have not been particularly visible issues in the campaign, Sens. Clinton and Obama have taken seemingly quite different stands on them. Clinton issues a detailed critique of the Bush Administration's handling of science in the fall, and it included both a call for more NASA focus on Earth science and for a robust human exploration program. Obama has said less, but has made a point of questioning the wisdom of spending lots of money to travel beyond low Earth orbit. Indeed, he said he would place a five-year moritorium on spending for space exploration beyond Earth orbit. Many have interpreted this as meaning he would halt or delay funding for the Constellation program, which is the new generation spacecraft system now being developped.
And regarding moon missions, the current plans call for something akin to a continuous presence on the moon -- some astronauts would be coming, living for a time, and going.
Woodbridge, Va.: It seems to me that NASA is building a case to return to the moon, which I think is a good idea. They're saying to the public, "hey we're not going up there just collect some rocks and play a round of golf." However, while the idea of more open access the univers excites me, a science nut, I don't think that radio telescopes are going to get NASA the support they need. I think they're going to have to kick it up a notch and add a goal to the list that's more symbolic and inspiring to capture the attention and enthusiasm of the American people.
Marc Kaufman: Interesting point, and something that NASA is definitely wrestling with. The Apollo program had its critics, but it was also hugely popular and made many Americans feel proud. The space shuttles, the international space station and orbitting observatories like Hubble all have their fans, but none has captured the imagination like Apollo did.
This is a problem, in that it limits NASA funding, but it also speaks to the very broad agenda that the agency now has. Hopefully it can continue with manned space exploration while also sending up new space obseratories -- like the Webb -- and starting projects like the lunar radio telescopes. They may not be as dramatic as a moon walk or a landing on Mars, but they would tell us things about the early universe that could forever change our understanding and sense of who and what we are.
Collinsville, Va.: What's your own personal view: Is concentrating on the moon, with a possible sustained manned presence there, a good idea, or should we go for broke to get to Mars?
Marc Kaufman: I don't really have an opinion, and believe that both could be absolutely fascinating. What I do have an opinion about is that NASA has been tasked with doing more things than it has funding to accomplish. The NASA budget is some $17 billion, which certainly is a lot of money. As a percentage of the federal budget, however, it is tiny, well under 1 percent. NASA projects can be very expensive and have not always worked out as planned, but it seems to me that the agency often provides something that is invaluable -- inspiration and insights into the vastness and complexity of our universe. We don't need NASA, but we would be considerably poorer without it, I believe.
Hoffman Estates, Ill.: I have heard the siren song of the "telescope on the dark side of the moon" played in the media many times in the past. Whenever the plans for such a device start to look realistic, like clockwork, comes the cold shower from various scientific experts; that trying to land a telescope on the moon would require all kinds of new technology and infrastructure, that lunar dust would be an ever-present hazard, that servicing such a 'scope would be a far more expense endeavor than a similar scope stationed in geocentric orbit over the dark side of the moon.
Frankly, all of those arguments have seemed awfully convincing to me. So what's new this time?
Marc Kaufman: You may turn out to be correct with your assessments of the feasibility/cost of a lunar-based mission, and much work must be done before this project gets off the drawing boards. The NASA funding is seed money of sorts for two groups, from MIT and the Naval Research Labs, to develop more detailed proposals to present to the National Research Council of the National Academies of Science. NAS will be doing its decadal survey pretty soon -- getting experts together from across the space community to prioritize projects. The lunar radio telescope may get high marks or it may not, and that will help determine whether it gets future funding. But this much is clear: If such a system could be established, it would provide remarkable information about the early universe. It's up to the experts to decide whether the technology is good enough to move ahead.
Man or Man-less: Is a manned mission to the moon necessary for placing a telescope there or can this be done with an unmanned landing craft and robots?
Marc Kaufman: Because of the number of antenna arrays that have to be placed, the expectation is that it will required a manned mission. Indeed, the Naval Research Laboratory proposal involves the placing of a prototype set of antennas near the lunar south pole, and for it to be done by astronauts. This would not be exactly on the far side of the moon, but close to it.
Rockville, Md.:"NASA should instead be thinking of heading to nearby asteroids or to Mars."
Perhaps, but the experienced gained by being on the moon could save lives.
Marc Kaufman: There is definitely a debate going on now between those who favor a return to the moon with settlements and those who see the proper next horizon as being Mars or a near asteroid. I can't claim any special insight into the pros and cons -- but I do know this will become a serious policy issue once we have a new administration.
Hoffman Estates: Hoffman Estates may be confusing proposals to have optical telescopes on the dark side of the moon (which would be subject to lunar dust and other concerns) with the MIT proposal, which would have no moving parts and would not be affected by the dust.
Marc Kaufman: Yes, the current proposals involve simple dipole antenna which probably can be made quite sturdy. Nonetheless, putting new technology onto the moon -- however straight-forward -- is bound to be a challenge, with unexpected problems.
Many thanks for all your questions, and I regret I didn't get to all of them. Until next time...
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