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Archive for August, 2009

Who Flung the Moon?

Thursday, August 27th, 2009

I did, that’s who! And on national TV, no less. But let me back up and tell the story from the beginning.

As regular readers of this blog know, I recorded an interview in June for a program on the History Channel called “The Universe.” Here are links to my previous blog posts about the interview:

  • History Channel, Part 1
  • History Channel, Part 2
  • History Channel and “This Week’s Finds”
  • History Channel Appearance — Next Tuesday!

The episode, called, “The Day the Moon was Gone,” debuted Tuesday night. Kay and I both thought that this was one of the best episodes of “The Universe” that we have seen. In my previous posts, I expressed some apprehension — about errors of fact that seemed to be creeping into the script, and about the general tendency of the program to exaggerate things. However, I am happy to report that most of the concerns I had did not materialize.

There were lots of good things about the episode. I was very interested to hear what the other scientists would say, and I thought that for the most part they had interesting ideas, including some that I would never have thought of myself. I really enjoyed seeing Bill Hartmann again. Everything he says just sounds so cogent and well thought-out. To me, he has the same sort of avuncular, “That’s the way it is,” presence that Walter Cronkite did.

I got quite a bit more camera time than I expected, and that was nice in a vain sort of way. The coolest thing was that they added some CGI effects to a couple of my clips. One time, when I was explaining tidal friction, I made some hand gestures to pantomime the moon moving outward from Earth. They dubbed in a little moon graphic to move along with my hands, so that it looked as if I was swinging the moon around in a circle and then flinging it away. What a feeling of omnipotence! I told Kay, “I should have called my blog, ‘Who Flung the Moon’!”

Other good points about the program: The pacing was not as frenetic as some episodes of “The Universe.” There was much less repetition than there often is. Most, though not all, of the topics were presented in logical sequence. Fundamentally, I think the concept worked. And that was a surprise to me.

When I first heard about the topic, a program about how Earth would be different if we had no moon, I was very skeptical. How, I wondered, could scientists answer a question with a fundamentally unscientific premise? The moon cannot disappear. So in some sense, you can make any statement you want, and no one can really prove or disprove it.

Nevertheless, I think that the episode worked because it got the scientists to think in unfamiliar and unexpected ways about the moon, and to bring out facts that they knew that maybe the average person doesn’t. Case in point: When I tell you that the solar tide is about 1/2 the size of the lunar tide, you yawn and say who cares? But when I tell you that if the moon went away you would suddenly have a huge tsunami as the water redistributes itself, all of a sudden it’s kind of interesting.

There was one minor disappointment for me. The narration did, on three or four occasions, try to argue that the giant impact that formed the moon is also responsible for Earth’s plate tectonics. I have previously discussed in this blog why I do not think that conclusion is correct. However, in the context of the whole episode it really was not that big a deal. I think that 95 percent of the audience probably did not even notice or care. I’m afraid that I lectured Adrian, the director, on this point so many times that by the end I was sounding pedantic even to myself. So I’m letting it go. Don’t let it spoil your enjoyment of the episode!

If you missed “The Day the Moon was Gone,” according to the History Channel website the episode will air again on September 8 at 8:00 Eastern time. I suspect it will also air at least a couple more times this week, but the website did not have those times listed.

Tags: giant impact, History Channel, interview, tides, Universe, William Hartmann
Posted in Media, Science | 1 Comment »

“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 »

History Channel Appearance — Next Tuesday!

Thursday, August 20th, 2009

 

The episode of “The Universe” on which I will appear — though probably only briefly — has now been scheduled! It will have its first showing on the History Channel at 9:00 pm (8:00 pm Central time) on the History Channel. For those people who don’t get the History Channel, I think that it will also be available on the Web. Go to the main page for “The Universe” and click on “Watch Full Episodes.”

The title of the episode is “The Day the Moon was Gone.” It looks at various scenarios for what Earth would be like if we had no moon. What if we had never had a moon? What if the moon suddenly disappeared?

Also, for those of you who missed my first appearance on ”The Universe” in 2007, they are re-running that episode (simply called “The Moon”)  just before the new one — 8:00 Eastern time, 7:00 Central.

If you have been following my blog entries — this one, this one, and this one – you know already that I have some concerns about the upcoming episode. I have not yet seen the episode, but I am worried that the show is going to exaggerate certain claims.  Some ideas might be presented or emphasized not because they are good science, but because they are good TV. After the show has aired, please feel free to ask me what I think is good science, what is doubtful, and what is just plain bogus. Keep in mind, though, that anything I say is just one person’s opinion! I can be wrong, too.

By the way, I have no such reservations about the earlier episode. On the whole I think that the History Channel (or really, Flight 33 Productions, which has produced all the episodes of “The Universe” except one) did a really nice job with that episode, and I am proud to have appeared on it.

Tags: Flight 33 Productions, History Channel, television, The Universe
Posted in Media, websites | No Comments »

Moon (the Movie)

Wednesday, August 12th, 2009

 

So far I’ve stuck pretty much to science in this blog, but I have promised to write about the moon in our culture as well. I’ve been looking forward to seeing the movie Moon, starring Sam Rockwell, ever since I first read about it this spring. It has been out for two months now, and I managed to catch it at a local theater that had it for a one-week engagement.

I’m very glad that I had not read anything about the plot of the movie, so that during the movie I was as clueless about what was going on as the character(s) were. Kay, who had seen a review on TV, knew more about the basic premise. So she picked up on the clues faster but missed out on some of the surprise factor. Nevertheless, we both liked the movie.

I am very much a fan of science fiction that takes place in a future we could conceivably get to, unlike such franchises as Star Trek and Star Wars that completely bend reality to suit the purposes of the storyteller. Moon has a very gritty, realistic feel. The lunar base feels claustrophobic. The space suits are always grimy. Things are broken and don’t get fixed. A central plot point, involving exposure to radiation, is a real possibility on the moon and something that the designers of lunar bases will have to contend with. (One hopes that they will never contemplate the solution portrayed in this movie.)

There are a few small holes in the plot that don’t spoil the overall story too badly. For example, any astronauts who go to the moon will certainly know about the danger of radiation and not be taken by surprise, as they seemed to be in the movie. Also, the astronauts are supposed to be on the far side of the moon, but one of them drives what seems to be a short distance and then he can see Earth.

One extremely cool thing about the movie is the computer, Gerty. It is obviously an homage to HAL, the computer in 2001: A Space Odyssey. I read one review on IMDb (after seeing the movie) that complains about the similarity, but I think it is delightful how the director plays with that cultural reference. Anybody who has watched 2001 will have certain expectations about how Gerty is going to behave — and let me just say that you will be very surprised.

Some of the visual elements of the movie are wonderful. I would nominate this movie for an Oscar in the following categories:

  • Most Effective Use of Emoticons. A little bit reminiscent of the Jack-in-the-Box commercials, but much better!
  • Best Use of a Full-Earth Shot. You’d think that we would be jaded, after seeing the Earthrise photos from Apollo, but the director gives us one look at Earth from the moon and uses the image very, very wisely. I was especially shocked at how huge Earth was — and, of course, that’s to be expected. Earth from the moon would look quite a bit bigger than the moon from Earth.

It’s interesting that the director, Duncan Jones, is the son of rock singer David Bowie, who of course had his own SF-oriented phase (“Space Oddity,” “Ziggy Stardust and the Spiders from Mars” and all that). I admire Jones for not shying away from his famous dad’s legacy, and exploring some of the same issues in a way that is completely different from his father. Also, as you might expect from the son of a musician, the music in the movie is very effective.

According to IMDb, Moon ranks in the top 250 movies (of all time!) in user rankings, coming in at #242, just above Rocky (#243) and just below Roman Holiday (#241). It has an average user rating of 8.4 out of 10. So a lot of people liked it! It probably won’t be in movie theaters too much longer, but if you can’t find it in a theater, perhaps you can catch it when it comes out on DVD.

Tags: dystopia, earth, fathers, lunar base, radiation, science fiction
Posted in Just for Fun, Movies, Science | 4 Comments »

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 »

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