LRO’s “BFF”

Monday, August 3rd, 2009

The second of the two moon missions that NASA launched in June is called LCROSS, an acronym for Lunar Crater Observation and Sensing Satellite. According to Tony Colaprete, the chief scientist for the LCROSS mission, “The younger folks at Goddard Space Flight Center have started calling it LRO’s BFF… at least until October 9.”

Hmmm… I can see some puzzled looks out there. Okay, I’ll explain. LRO is the Lunar Reconnaissance Orbiter (LRO), which launched on the same rocket as LCROSS on June 18. BFF is Internet-speak for “best friends forever.” (But you knew that already, right?) And October 9 is D-day for the LCROSS mission.  Unlike LRO, which will accumulate its results slowly and steadily over a period of one to three years, LCROSS will go out in a blaze of glory, and will do all of its most interesting science over the course of 5 minutes.

LCROSS consists of two main pieces — a spent rocket booster and a “shepherding satellite.” On October 9, around 4:30 AM Pacific time, the bigger rocket booster will slam into a crater near the moon’s south pole. Imagine an SUV crashing head-on into the ground at more than 5000 miles per hour! That’s what the impact is going to be like. It will be equivalent to the explosion of about a ton of dynamite. 

The explosion will be big enough, in fact, to be seen from Earth. That is the whole idea — to time the impact so that it can be tracked by all of the big telescopes on Hawaii, as well as the Hubble Space Telescope. Colaprete says that even a 10-inch telescope (well within the range of many amateur astronomers) should be able to see the flash, if it is pointed in the right place at the right time. If you don’t have access to a 10-inch telescope, you can also watch the impact over the Internet.

A minute or so after the big kablooie, the shepherding satellite will come swooping in, flying right through the debris plume. While it’s getting buffeted about, it will hopefully be able to sniff out any volatile compounds that have been excavated by the blast, including water vapor — the number one target of the mission.

We’ve seen tantalizing hints of water ice from orbit, but nothing that absolutely confirms it. We know that there is hydrogen in the permanently shadowed craters near the south pole, but there is no guarantee that the hydrogen is bound up with oxygen to make a water molecule. There’s only one way to find out for sure, and that is to “reach out and touch it,”  as Colaprete says. Or perhaps “reach out and blow it up” would be a slightly more accurate wording.

After it flies through the plume, the shepherding satellite will itself crash into the moon a few minutes later, creating a second and smaller blast. Colaprete is deliberately not building up any great expectations for this one, because it will be harder to control where the shepherding satellite lands. However, it will give scientists a second chance to look for signs of water, or at least to understand the mechanical properties of the ground that LCROSS is crashing into.

Last month I had a chance to interview Colaprete by e-mail and then in person at the Moon Fest. I also went to his talk at the Lunar Science Forum. In my next post I will try to reproduce these three “conversations” as if they were all one interview.

By the way, the LCROSS mission reminds me of something interesting I learned when researching my moon book. After Russia launched Sputnik in 1957 and when our scientists and politicians were debating what we could do to respond, one of the crazy ideas that was floated was to nuke the moon. That’s right, launch a nuclear missile at the moon and blow it up, thereby proving somehow that we were bigger and badder than the Russkies.

What a stupendously bad idea this would have been, because we would have learned nothing from it. The response we chose instead — sending men to the moon — was vastly more difficult, but we got so much more out of it, including a real understanding of the moon’s origin and makeup, plus the fleeting goodwill of all of the rest of the world.

It’s just a tiny bit ironic, then, that on our second round of missions to the moon, one of the first things that we are doing is slamming a rocket as hard as we can into the moon to create a big explosion. I mention this parallel with some hesitation, because I don’t want to make LCROSS seem like just a stunt. That is exactly what it is NOT. There are two huge differences between this mission and the stunt that was proposed back in the late ’50s:

1. A spent rocket booster is not a nuke.
2. The LCROSS mission was designed with a specific scientific purpose in mind: to excavate water ice, to see first of all if there is any ice there and secondly how much there is and how easy it is to get it out. These are vital things to know if we are ever going to set up a permanent moon base.

Maybe these points are obvious and didn’t even need saying, but I just wanted to explain why the LCROSS mission is not just about some engineers blowing things up for fun.

(Still, blowing things up is fun … See any episode of Mythbusters for proof!)

Tags: blaze of glory, hydrogen, ice, kablooie, LCROSS, Mythbusters, nuke, Tony Colaprete, water
Posted in Science | 2 Comments »

A colder and wetter moon?

Wednesday, July 22nd, 2009

Yesterday I went to the Lunar Science Forum at Ames Research Center, which was the scientists’ version of a Moon Fest – a chance for all the recent and current moon missions to unveil their latest and greatest findings. According to the organizers, more than 500 people registered, including 200 just since last Friday. I don’t think that all these people actually came — the main meeting room holds 300, and it was not filled to capacity. Nevertheless, it was a well-attended (and well-Twittered) event.

Yesterday the science teams of the LRO and LCROSS missions, which just launched last month, presented their data publicly for the first time. As David Morrison, the head of the Lunar Science Institute, said in his introductory remarks, “Last year most of the papers reported plans, but I’m delighted to say that most of the talks this year are about results.”

All of the LRO results are very preliminary, because LRO is still in its “commissioning orbit,” when they are still warming up and checking out the systems. By the way, I mean warming up quite literally. Most of the instruments have residual moisture in them from their time on Earth. (So do most tourists, after a few hours in the humidity of south Florida!) So they have to go through a “bake-out” period to dry out all of that extra moisture. The LRO camera finished its bake-out on July 10, but even before then (as mentioned in this entry) it started sending back fabulous pictures.

Also, scientists from two other moon missions spoke yesterday. There was one presentation on the Japanese Kaguya mission that just ended a week before LRO lifted off, and three about the Indian Chandrayaan-1 mission that is still ongoing.

The most interesting news yesterday all had to do with results that we can’t really talk about yet! One of them is so preliminary that no one can really interpret it yet. The other two are results that are going to be published soon but are currently under “embargo,” meaning that the scientists aren’t supposed to talk about them until the publications come out.

First, David Paige, principal investigator for LRO’s Diviner experiment, showed some of Diviner’s first measures of the temperatures in the moon’s permanently shadowed craters. Remember that these are supposed to be “cold traps,” where water molecules could perhaps accumulate as ice because they are too cold to float away. The first temperature readings in Amundsen crater turned out to be even lower than expected: around 33 degrees Kelvin (or 33 degrees above absolute zero).

No one had predicted such a low temperature; I think that 70 degrees Kelvin was closer to what they had expected. As Paige said, “If this is true, it’s colder than the poles of Pluto!”

From his wording, you might correctly infer that Paige is not really sure this measurement is right. The instrument has been calibrated, but he said there are some possible reasons why the instrument-measured temperature may not be the same as the physical temperature. (For example, they don’t really know what kind of surface they are looking at — rocky or soft and fluffy — and that can make a difference to how they estimate the temperature.) The instrument is still too fresh and new, and the finding too unexpected, to put a lot of stock in it yet. But what it could mean is that the permanently shadowed craters are a better cold trap than we thought.

Two other surprising results that can’t be talked about yet came out of the Chandrayaan-1 mission. Carle Pieters of Brown University reported on the Moon Mineralogy Mapper, and said that her team had made a new discovery on lunar volatiles that she can’t discuss yet. Of course, the most important potential  ”lunar volatile” is water. But, she said, “Don’t give me wine and try to dig the secret out of me.”

Then Paul Spudis, whose Once and Future Moon blog is always thought-provoking, talked about the results from his mini-SAR (synthetic aperture radar) experiment, which is also on the Indian Chandrayaan-1 spacecraft. Like Pieters, he has a result that he can’t talk about yet, but he said, “I may be susceptible to being plied with drinks!”

Mini-SAR is also looking for water ice; the idea is that ice will reflect a circularly polarized radar beam differently from rocks. (The radar wave will actually go into the ice before bouncing back, because ice is transparent.) This is similar to the way that ice was first detected at the south pole, by the Clementine mission in 1994; Spudis was the deputy leader of the Clementine science team. However, the Clementine satellite only got one brief peek at the south pole, and so its results were very ambiguous. You can’t do very much in science with one data point. Chandrayaan-1 should do much better. We will have to wait to find out just how much better it’s done.

Nevertheless, I will transcribe a fascinating exchange that occurred during the audience-questions period after Spudis’ talk. Clive Neal, the chair of NASA’s Lunar Exploration Analysis Group (which advises NASA on the choice of moon missions) went to the microphone.

NEAL: You said there were some things that you cannot talk about, but then you proceeded to talk about some of them… (Laughter from audience.)

SPUDIS: You don’t know that! (Laughter.) You’re making an assumption, and maybe it’s warranted, maybe it isn’t.

NEAL: So I’ll ask my question as delicately as I can. You showed data that seemed to be consistent with the presence of water ice on the moon. Would you care to comment on that? (Loud laughter.)

SPUDIS. No! (Laughter.) But you’re welcome to draw whatever conclusions you care to.

NEAL: Can I just rephrase the question? If I buy you a beer, would you comment?

SPUDIS: It depends on what kind of beer and how much. (Laughter.)

DAVID MORRISON: I think all of us are beginning to assume that in a month or two we’ll have a wetter moon than we do now.

SPUDIS: Well, the moon isn’t going to change. (Laughter and applause.) Our perceptions might change. But, you know, some of us have had this perception for a long time.

Make of it what you will! Just don’t blame me for breaking any embargoes.

Other tidbits and factoids from the first day of the meeting:

These roads are so confusing.

• Google released its new version of Google Moon on Monday, and there was a large screen in the tent demonstrating it. It’s a huge improvement over the previous map-based Google Moon. This one has all the latest imagery from the LRO mission, and will continue to be updated constantly — so look for it to continue improving by leaps and bounds over the next year.
• The LRO launch was perfect, and that is very good news for the scientists, because it means that there is more fuel left for an extended mission than they could previously count on. Craig Tooley said that this could extend the life of the mission by a year. (The spacecraft has a planned one-year life span, followed by a two-year extended science mission. I interpret Tooley’s remarks to mean that it could continue orbiting for a fourth year.) I would think that the extra time would be especially valuable for the narrow-angle camera, which can only image about 10 percent of the moon in any given year.
• I asked Sam Lawrence, of the LRO camera team, whether they had felt under any pressure to get the pictures of the Apollo landing sites out early. He said, “I won’t lie to you. Several people in Headquarters simultaneously and independently came up with the idea of taking pictures of the Apollo landing sites. But Isaac Newton is in the driver’s seat. It was largely serendipity that we happened to be in the right place to image them.” In fact, the Apollo 12 landing site has not been imaged yet, but it should come around into the camera’s view in a couple of weeks.
• There was lots of Twittering going on at this conference. I sat behind someone whose laptop had a screen full of twitters. I have so far refused to get on twitter.com, but those of you who are might want to check out what the scientists are twittering about.
• Yes, there is such a thing as a free lunch! Registration for this conference was free (which is already unusual for a scientific meeting) and the Lunar Science Institute provided the lunch and refreshments free of charge, too! Shhh… Don’t tell Washington that they’re using your tax money to feed starving scientists …

Tags: Ames Research Center, beer, Chandrayaan, cold trap, free lunch, Google, ice, Kaguya, LCROSS, LRO, Lunar Science Forum, Lunar Science Institute, Twitter, water
Posted in Just for Fun, Missions, Science | 1 Comment »

LRO First Picture!

Saturday, July 4th, 2009

Two days ago, on July 2, NASA released the first photograph from the new Lunar Reconnaissance Orbiter. And here it is! (Actually, this is just a small piece of it, but a very interesting piece, as I will explain below.)

LRO First Light

The complete photograph is actually a very long strip, something like 500 by 50,000 pixels, taken near the edge of Mare Nubium in the moon’s southern hemisphere. The LRO website ways that the photo was taken near a crater called Hell … I’m not sure why. It doesn’t seem like the best place to start a mission!

If you want to find the location through a telescope or binoculars, it’s at about 30 degrees south latitude and 10 degrees west longitude. To the south is Tycho (one of the brightest craters on the moon), and to the north is an easily spotted trio of craters, Ptolemy, Alphonsus, and Arzachel. The best time for looking at this region was two days ago, when the picture was taken — and that is no accident. Photographers on Earth like to take pictures at sunset or sunrise, and so do lunar photographers! The lunar topography shows up most clearly near the “terminator” — the boundary between the day side and night side of the moon. The LRO spacecraft is currently in a terminator orbit, circling the moon from pole to pole and following the moon shadow around. This is the place to be if you want to take stunning photographs!

There are two very interesting things to notice in this picture. First, at the very bottom, you might notice a string of craters, like beads on a chain. Is this an accident? If not, how is a chain of craters like this formed? The answer is that they are “secondary craters” — craters formed by debris that is blasted off the moon’s surface by a meteorite impact. When the debris lands, it forms smaller craters all in a line. The first person to notice this phenomenon, I believe (perhaps some historians can correct me if I’m wrong) was Ralph Baldwin, an amateur astronomer in the 1940s. At the time, the conventional wisdom was that the moon’s craters were volcanoes. Baldwin put together many pieces of evidence, like this, to conclude that at least some of them were formed by impacts.  In this case, the amateur was right and the professionals were wrong.

Also, Baldwin noticed very large-scale linear patterns on the moon, which again seem to radiate outward from some of the great basin impacts. According to the LRO team, you can see some of the linear features in the photograph. I suspect that what they mean is the overall southwest-northeast orientation of the valleys in this photo. These furrows must have been scoured out by a vastly larger and earlier impact than the one that made the little chain of craters that I mentioned above.

As cool as the LRO pictures are, I want to mention that LRO is way, WAY more than just a camera. It has seven extremely cool instruments on it. I will list them below in no particular order of coolness. I will not translate the abbreviations into English — if you want to know what they stand for, check out the LRO website.

1. LAMP. How cool is this? We are going to see the dark regions of the moon by starlight. The stars give off ultraviolet light, and the whole darned galaxy glows at one particular wavelength, and we can use this invisible (to human eyes) light to peer into craters that never see the sun.
2. Diviner. We’re going to take the moon’s temperature. It’s not the same everywhere. Equatorial regions range from 150 degrees below zero (Celsius) to more than 100 degrees above zero (i.e., hotter than the boiling point of water).If you’re building a lunar base, that’s kind of tough to deal with. But near the poles, the temperature is much more even, although cold — roughly 100 to 120 degrees below zero.
3. CRaTER. This one is interesting because it is specifically directed towards human habitation. How much radiation does the moon get from the sun and from outer space? The answer will tell us how long we can keep astronauts on the moon’s surface safely. Remember that the Apollo astronauts were there for only three days or less.
4. LEND. Another instrument that will measure radiation — this time neutrons coming from inside the moon. This is kind of a repeat of the experiment that Lunar Prospector did to confirm the presence of hydrogen (and therefore maybe water) at the poles. An interesting point here is that it’s a Russian experiment flying on a NASA spacecraft — a nice example of international collaboration!
5. LOLA. This laser altimeter will construct 3-D images of the moon’s surface.
6. Mini-RF. A synthetic aperture radar that will search for ice at the lunar poles. This is similar to the Clementine experiment in 1994 that started all the excitement about water at the poles, but I assume it will be much better because it will have a lot more time to gather data and because it was designed for this purpose.
7. LROC, the LRO camera, which by now needs no introduction.

I am by no means an expert in all of these technologies (or any of them), but I hope that over the coming months I will have a chance to interview some of the scientists involved with these projects, so that I can tell you how they work.

One thing that I find interesting about the web links is that almost all of them mention that they are “heritage” or “legacy” instruments — in other words, similar experiments have flown on other NASA missions, to Mars or to other planets. In our budget-conscious age, NASA wants equipment that is cheap and reliable. Still, one can’t help feeling a little bit nostalgic for the 1960s and the Apollo missions, when nothing was a legacy experiment — everything was being done for the first time!

Tags: craters, equator, ice, LRO, NASA, opinions, poles, radiation, technology, telescope, water
Posted in Missions, Science | 5 Comments »