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Posts Tagged ‘Kaguya’

“That’s Daddy’s rocket!”

Tuesday, August 25th, 2009

 

In an earlier post I wrote about the LCROSS mission, which is due to make its crash landing on the moon on October 9. (Mark your calendars!) In July I talked with Tony Colaprete, the Principal Investigator for the mission. I apologize if there is a bit of unevenness in this interview, because I have cobbled it together from three sources — our conversation at the Moon Fest, an e-mail, and his presentation at the Lunar Science Forum. Answers have been edited for length but I have tried to preserve Tony’s wording.

Tony Colaprete (NASA photo)

Tony Colaprete (NASA photo)

DM: You told me that you were born the week before the Apollo 11 landing. So, happy birthday! How big an inspiration have the Apollo missions been to you?

TC: I was born July 16, 1969, the day Apollo 11 launched. My father was heavily involved in the Apollo program, and one of my early childhood gifts was the classic Snoopy dressed in an EVA suit. So, yes, the Apollo mission was a huge influence, not only because they were so amazing but also because of my father’s involvement. … I am amazed to think that the folks who did Apollo were on average around 25 to 27 years old! The commitment, devotion, and guts those people had is inspiring.  I just hope I can do things half as right as they did for the Apollo program.

DM: When and how did you decide that you wanted a career in space exploration? How did you prepare for it?

TC: When I graduated from high school I knew I wanted to either go into the sciences or art. Luckily for us all, I decided to go into the sciences. … Very early on, though, I loved being in the woods near Boulder, Colorado, where I grew up. I would go for hours by myself and just watch what went on around me. So very early on I knew I loved systems, how things work together and influence each other … I still do.

I worked on instrumentation at the University of Colorado through the Space Grant College and the Laboratory for Atmospheric and Space Physics for a few years after getting my bachelors degree in physics. I was taking a few graduate classes (including my first planetary atmospheres class, taught by a very inspiring David Grinspoon), when I realized I wanted to pursue a graduate degree in planetary sciences. Luckily, CU is a great place to do that!

While I was doing my graduate work I continued to work on instrumentation for sounding rockets, space shuttle flights, and small spacecraft. This combination of science and engineering (again, systems!) was key, I think, to helping me get where I am now.

DM: How did the idea for the LCROSS mission come about?

TC: When LRO moved up to a bigger rocket, they had room for an extra 1000 kilograms on board, and a call for proposals went out for a co-manifested mission. And by the way, they said, you have only 2½ years to get it done, and you can’t spend more than $80 million.

When the call was announced, we [at NASA Ames] formed a “Tiger Team” to come up with ideas. Early on in the process we considered an impact mission, but I concluded that with only 1000 kilograms to work with, the impactor mass would be too small.

Another person in the group, Geoff Briggs, suggested using the spent upper stage of the launch vehicle. He has since said that he got the idea from someplace else. I ran some numbers and convinced myself that an impact by an object of about 2000 kilograms would produce a cloud observable from earth.

At about the same time, Northrop Grumman submitted a [proposal] that was also using the upper stage and also had a small shepherding satellite that could make observations. An engineer on the Tiger Team saw the idea and told me about it. We had a couple Northrop Grumman scientists come up and we discussed our ideas and the rest was history. So I don’t think it was any one person’s idea, but just enough people with the same idea!

In the end, LCROSS was selected out of 17 proposals. We cheated the 1000 kilogram limit — it’s 3200 kilograms, because we held on to the spent Centaur [rocket stage], which is about 2300 kilograms.

DM: Have you ever watched a launch in person before? If so, how was it different, knowing that it’s your own experiment that is going up?

TC: I’ve flown payloads on sounding rockets and shuttle flights, and have seen those go before. This Atlas moved so slow at first! I thought to myself, “You’d better pick up some speed or you’re not going to make it!” The sounding rockets and the shuttle use solid fuel, whereas the Atlas V is all liquid — it’s a big difference!

My biggest concern at launch was whether we could get off on the 17th or the 18th [of June], because those two days result in very good impact observing conditions for the continental U.S. The 19th was not so good, and on the 20th [there were no good times] at all. So I was very glad the weather broke in time for us  to go on  June 18.

DM: Have there been any exciting moments since the launch?

TC: I held my breath when we turned on the instruments for the first time. That was a moment of sheer terror and anxiety for me. Also, I’ll hold my breath again on August 1, when we turn them back on. Radiation and vacuum can have effects on detectors, so they always degrade over time. Once we know that they are working, I will be very confident that the payload will survive until the impact with the moon. [According to the mission page, the checkout of the infrared cameras and spectrometers on August 1 went very well. They took spectra of Earth and -- stop presses! -- detected oxygen, water, and vegetation! -- DM]

DM: What are you expecting to see when LCROSS hits the moon?

TC: There are a couple different models of how the water gets to the south pole and two different predictions for how it is distributed. We describe them as the smooth versus chunky models. In the smooth model, the ice is uniformly distributed on the scale of this room, with about a 1 percent concentration of ice. If that model is correct, LCROSS will have very good chances of detecting it. LCROSS should be sensitive down to concentrations of half a percent.

However, if the ice is chunky, with smaller pockets of up to 10 percent ice, then we might have a 10 percent chance of hitting something. If we hit one of the “peanuts” in the chunky peanut butter, we’ll know. This would immediately distinguish between the two competing models.

My biggest fear is that we won’t see anything — that it will be a dud. But even in that case, then we’ve learned that the distribution isn’t smooth. That is important to know, because it means that your next mission [i.e., a lander to search for ice on the ground -- DM] had better be mobile.

DM: How does the LCROSS mission compare with other spacecraft that have crash-landed on the moon (Lunar Prospector, the European SMART-1, and the Japanese Kaguya)?

TC: None of those other missions were designed as impactors. The biggest difference is that they typically hit the moon at a low, grazing angle, because they were in orbit around the moon. LCROSS is not, it’s in orbit around the Earth. [This is a rather non-obvious fact that is illustrated on the flight director's blog at this link. LCROSS doesn't "go to the moon." It goes into an orbit around Earth that is the size of the moon's orbit, and then the moon just runs into it! - DM] So it will hit at a very steep angle, around 85 degrees. Also, we’re bringing quite a bit of mass. So those missions can’t be compared to LCROSS for visibility, size, and impact angle.

DM: How big a crater will the LCROSS impact make?

TC: We’ve done simulations using Apollo-era technology, and we expect the crater to be about 20 meters wide — the size of a tennis court. We expect the plume to contain about 300 to 400 metric tons of material.

DM: On the LCROSS website you have a list of several possible target craters. Do you have a favorite on this list?

TC: Faustini would be my preference. It’s a very old, large crater, so the material in there has been in shadow for a very long time — around two and a half billion years. We want to hit somewhere that is flat and fluffy, not blocky and steep. One thing against it is that it’s right on the limb of the moon. So the ejecta have to go up 2 kilometers in order to be illuminated by the sun. In some of the other target craters, the ejecta only have to go up about 500 meters. But for earth observers, a position on the limb means that you get high contrast [against the darkness of space -- DM], and that’s good.

DM: I think it’s interesting how you have been able to use the results of other recent missions to narrow down the list of targets for this mission. Can you talk a little bit about  the synergy between missions, and especially the Japanese Kaguya spacecraft?

TC: The topography from their laser altimeter has been invaluable. First, it lets us calculate the slope of the ground. You don’t want to hit a slope [because you would then lose the benefit of a high impact angle -- DM]. Kaguya also gave us amazing information on the depth of the craters. Some of the errors in the previous estimates were significant, on the order of 500 meters to a kilometer. From the Kaguya terrain camera we got information on the surface roughness and albedo [reflectivity] of the craters. So, overall, they matured our current data set.

Also, with new LRO data coming online, we’ll be refining our numbers continuously to make the wisest choice of target. We will finally make an impact site selection by 30 days before impact, roughly the first week of September.

DM: How can ordinary people contribute to the LCROSS mission?

TC: Amateurs have already contributed, and with an impact with the moon high and the skies dark as far east as Texas, I hope many more will continue to contribute.

One thing to realize is that professional astronomers typically don’t point their telescopes at the moon. To most of them, the moon is a source of light pollution. So when we asked the best in the world to look at the moon for a change, there was a steep learning curve. One thing they needed to learn was how to find the crater you want to point to amongst a hundred or so other craters that look very similar. The shadows and bright areas change dramatically with small changes in the sun angle, so finding one’s way around the moon can be difficult if one has never looked before. To help, we asked the amateur community to image the moon at all phases and tilts so that we had a library of sorts for the various light conditions.

During the impact, amateurs with a minimum of about a 10-12 inch telescope can observe the impact. We will be soliciting these observations and will share them with others. [There is a Google Group for amateur observers at this link -- DM.]

DM: Finally, do your kids know that “Dad is a rocket scientist”? If so, are they proud of it, and are they paying any attention to the LCROSS mission?

TC: I have a son who is two and a half and a daughter who is five years old. They came to the launch, and when they look at the moon now they say, “Daddy’s rocket is flying to the moon!” After the launch my wife and children took a different flight home than I did. During the layover, on one of the cable news channels playing at the gate, they showed a replay of the launch. My children both yelled, “Daddy’s rocket!” My wife says that the people around them looked with a bit of a skeptical stare until she said, “Actually, it is their daddy’s rocket.”

Tags: Ames Research Center, Apollo, chunky, craters, interviews, Kaguya, LCROSS, LRO, Northrop Grumman, smooth, telescopes, Tony Colaprete
Posted in Missions, Science | 3 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.

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 »

Liftoff!

Friday, July 3rd, 2009

We're on our way!
We’re on our way!

To all space enthusiasts, especially those who are interested in the moon, welcome! I’m celebrating the launch of my blog, appropriately enough, with a picture of a rocket launch. On June 18, 2009, NASA successfully sent its first two lunar missions of this millennium into orbit: the Lunar Reconnaissance Orbiter (LRO) and Lunar Crater Observation and Sensing Satellite (LCROSS). (Image credit: United Launch Alliance/ Pat Corkery.)

LRO Logo in center, LCROSS just above it

LRO Logo in center, LCROSS just above it

It’s an exciting time to start a moon blog. Not only have the LRO and LCROSS missions gotten underway, but also the Indian Chandrayaan-1 mission is still going and the Japanese Kaguya mission has just ended. We also have a big anniversary coming up: the fortieth anniversary of the Apollo 11 manned mission to the moon. Two days after that, the longest total solar eclipse of the 21st century will take place — and as you know, we wouldn’t have eclipses without the moon.

That is a sample of the topics I plan to cover in my blog. I also hope to include interviews with people who are working on moon-related projects, whether they be NASA or private, science or literature or art. Yes, I do intend this blog to be not just about lunar science. The moon plays a large role in our culture, so I don’t think that we should just stick it in a box labeled “Science” and forget about all the other things that the moon means to us. But that’s a topic, or discussion, or rant for another time!

This blog takes its name from the working title of a book that I wrote six years ago, which was published by John Wiley & Sons: The Big Splat, or How Our Moon Came to Be. It’s a figure of speech my grandfather used to employ often. If you “think so-and-so hung the moon,” that is another way of saying that you are a great admirer of said person.

Eventually, my editor and I decided that “Who Hung the Moon?” was not an appropriate title for the book. The main reason, for him, was that book titles should not be in the form of a question. This was news to me — hadn’t he ever heard of “Who’s Afraid of Virginia Woolf?”? My reasons were different. I was concerned that “hung the moon” might be an idiom from a specific region — the American South — and not everyone would understand it. And finally, “Who Hung the Moon?” didn’t quite say what the book was about. The title we chose, The Big Splat, or How Our Moon Came to Be, was a much more straightforward description of the book’s contents.

Nevertheless, I still like the abandoned title. But it was actually my SO (Spousal Overunit), Kay, who suggested reviving it as the title for this blog. She did more than suggest it — she designed the whole look of this webpage around it, so that by the time she was done I couldn’t possibly say no! If you like the design, please send your compliments to her (and check out her quilting blog, www.allaboutapplique.net).

See the “About” pages if you want to read more about my background and reasons for writing this blog. But now, let’s get started!

Tags: Apollo, Chandrayaan, eclipse, Kaguya, LCROSS, LRO, NASA, spousal overunit, The Big Splat
Posted in Missions | 4 Comments »

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