Anthonares

While most folks remember Apollo for the videos and photos it returned of a foreign, desolate world, some of the science experiments left behind have gone under-appreciated. Two of the science experiments, the Lunar Laser Ranging Experiment and the lunar seismometers (Passive Seismic Experiments), returned data long after the astronauts left. While the lunar seismometers were turned off in 1977, the Lunar Laser Ranging Experiment (LLRE) continues to this day, and has produced some incredible results. For instance, we now know that the Moon still has a liquid core, that the fundamental gravitational constant G is either static or is evolving very very slowly, that Einstein’s General Theory of Relativity predicts the Moon’s orbit better than we can measure it, and that the Moon is receding from us at a rate of about 3.8 cm/year.

The primary reason that the LLRE has been so successful is that it is allows for almost unlimited upgradeability in precision, is free to use, and costs no money to maintain. In the 35 years since the first LLRE reflector was deployed by the Apollo 11 astronauts, dozens of teams have used the laser reflectors to learn more about lunar geology and the evolution of the Earth/Moon system, as well as to conduct basic physics research. Scientists continue to use the LLRE reflectors today and are constantly improving their accuracy so that in the coming years new research can be conducted with these astounding little experiments.
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In my undergraduate cosmology class my professor introduced this satellite as having brought about quantitative cosmolgy. While that’s probably just a bit of an exaggeration, this little craft definitely revolutionized the science. Prior to the launch of the Wilkinson Microwave Anisotropy Probe (WMAP) (and to a much smaller degree its predecessor, COBE), cosmology, the study of the evolution of the universe, was a mess of theories and ages. But after a series of papers published in 2003 detailing the first year of data collection from WMAP, the universe suddenly had a definite age, 13.7 billion years, and was shown to be dominated by dark energy.

Since then, WMAP has been the darling of the astronomy community and has undoubtedly led hundreds of eager young undergraduates into cosmology. The science community knew that WMAP was still collecting data, but I’m not sure that anyone really expected the news released last week (discussed at Cosmic Variance and at Bad Astronomy, here are the technical publications). The age of the universe was left unchanged at 13.7 billion years, but the date of first star formation was moved to 400 million years in better agreement with theory. Also, the first true evidence for cosmic inflation was presented as well.

It was an exciting announcement from a team that has already done so much for the field of cosmology. To better understand just why the WMAP mission is so important, I’ve put together this relatively brief summary of the study of the Cosmic Microwave Background in the last decade. These three missions have changed our prospective and refined our vision. Cosmology is now a field of true quantitative prediction that bears little resemblance to the unorganized conjecture of two decades ago.
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Almost two weeks ago, Cassini mission scientists published a host of results pertaining to Saturn’s tiny moon Enceladus. The world had been given a hint of what to expect from the image on the right released last November that revealed a geyser of material spewing away from the south polar region of the moon. We were treated to a literal feast of fantastic results, summarized in this perspectives article by Jeffrey Kargel (a hydrologist at University of Arizona). Because of the importance of these new papers, the journal Science is offering free access to the 11 articles published in the March 10th issue relating to Cassini and Enceladus. You can spend $10 to buy the newsstand edition, gotta love free and open science!

As much as I would love to review all of the Enceladus science, so many important discoveries could not receive the attention or care they deserve in a single blog entry. Instead I will focus just on the discovery of watery geysers emanating from Enceladus’ south polar region. I will focus on the two papers detail the discovery of water ice in that jet of material, though two additional papers provide the important linkage between that jet and relatively warm surface features. The so-called tiger-stripes seen on Enceladus occur on a geologically very recent portion of the moon’s crust (Porco and others), and are shown to be about 70 degrees warmer than the surrounding crust. This makes the tiger stripes about 145 Kelvin, or -128 Celsius, while the surrounding crust is a chilly 70 Kelvin (Spencer and others).

Citations

• Hansen, CJ, and 7 others (2006). “Enceladus’ Water Vapor Plume.” Science 311(5766), pp. 1422-1425. [online at CiteULike.org]
• Waite, HJ, and 13 others (2006). “Cassini Ion and Neutral Mass Spectrometer: Enceladus Plume Composition and Structure.” Science 311(5766), pp. 1419-1422. [online at CiteULike.org]

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Following the discovery of what appeared to be an ice-filled crater early this year, the MARSIS team announced that they have discovered a thin layer of water ice surrounding the southern polar ice cap. Though the layer is not very thick, its extent means that it contains about half as much water as the southern polar cap.

These findings were announced at this year’s Lunar and Planetary Sciences conference. As soon as they are published, or more details emerge, I will cover the story further here.

One of the reasons that astronomy appeals to so many people are the stunningly beautiful photographs of nebulae throughout our galaxy. Tomorrow’s edition of the journal Nature features a paper that explains just how a cloud of gas was twisted and formed into a double helix shape. NASA’s Spitzer Infrared Telescope took this color-enhanced image of the nebula.

Twisting and interacting magnetic fields near the center of the galaxy are probably the culprit here, according to the article (see the citation below). When viewed in this broader-context image (taken using the Midcourse Space Experiment satellite), the twisting double helix nebula appears to be emerging nearly vertically out of the galactic plane. This fact, combined with the temperature of the gases and their proper motions provide strong evidence that the galaxy’s central magnetic field has sculpted this nebula.
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Here’s a short article that I wrote for DamnInteresting.com, but I finished it a bit late in the day so I’m not sure that it will get published:

Mathematicians (I won’t call them math geeks) are not generally considered wild partiers. Positioned in front of whiteboards endlessly writing arcane proofs and derivations, they seem more the quiet type. But today, on March 14th, the entire math world sets down their dry-erase markers, breaks out the party hats and eats a slice of pie. Why? Because it’s Pi Day!

But math geeks worldwide (there, I said it) aren’t just celebrating the happy coincidence of the date and the first few digits of pi (3.14159265…). Pi day gives them a chance to celebrate the deep mystery of the universe, along with marvelous history of mathematics, by paying homage to that little greek letter that appears in so many equations.
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While working on my new condominium (well not exactly while I was working, in the evenings more like), I enjoyed some great reading this last week, and some really terrific news from Enceladus. I’ll be writing a published research synopsis on the Science paper later today (I’m sure you’ve all been waiting to hear about how the water geysers were detected and confirmed). Also, there was some exciting news in the alt.space community with the announcement of the Dragon manned capsule by SpaceX.

As on most Mondays, today’s fantastic skeptical examination of the Aviation Week article last week about the supposed Blackstar hypersonic spy aircraft/orbital spaceplane. Dwayne Day methodically exposes the uninformed speculation that sent so much of the apparently overly-credulous space blog community into a tizzy last week.

In that The Space Review article, Day mentions that the optical adaptive optics/laser guide star system rumored to have been installed on the Blackstar would not work from above. Let me go over just why it would not work, so you can better see the difference between science and psuedoscience in this case.
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My wife and I are buying our first home, and we are going to use Spring Break to clean, paint, and install floors, lights, and everything else. So, I’ll be taking a week off here unless something comes up that I feel the need to write about. Also, this will give me a chance to catch up on my reading a bit. I hope to see you back here next Sunday!

Before reading this week’s Published Research Synopsis, hop on over to DamnInteresting.com and check out my latest entry A Big, Big Hole in the Ground. Now that you have the basics down about the Yellowstone Supervolcano, we can dig a little bit deeper into what geologists are doing to monitor it.

Astonishingly, modern satellite remote sensing techniques are capable of actually “seeing” the magma flow deep beneath the surface. The magma slightly deforms the crust above it, and by measuring that deformation and comparing it to computer models, the authors of today’s paper convincingly estimate the volumes and timing of magma flow beneath the surface. For the first time, then, we are given a window into the hidden world deep beneath Yellowstone’s feet. And a very important window it is.

Citation

Wicks, CW, Thatcher, W, Dzursin, D, and Svarc, J (2006). “Uplift, Thermal Unrest and Magma Intrusion at Yellowstone Caldera.” Nature 440(7080), pp. 72-75. [online at CiteULike.org]
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Last night, PBS aired a two-part series on NOVA about the search for the Northwest Passage and two of the most famous Arctic explorers, John Franklin and Roald Amundsen. As I watched I realized something that helped to put much of the discussion about Martian exploration into perspective: Arctic and Antarctic explorers would spend up to several years at a time on any given expedition.

These weren’t years spent in the relative shirt-sleeves comfort of a pressurized, climate-controlled Mars base either. They were fitful, short summers bracketed by horrifically cold and dangerous winters. Supplies were often quite limited, and scurvy and tuberculosis were constant threats. There were no radios (though the final Shackleton expeditions did carry radios for part of the journey), and absolutely no communications with home. Support teams were non existent, resupply missions were impossible, rescue was unlikely, and the psychological conditions of the journey were simply brutal. In the words of Shackleton in an advertisement in the Times of London in 1901 (historically disputed, btw):

Men wanted for hazardous journey. Small wages. Bitter cold. Long months of complete darkness. Constant danger. Safe return doubtful. Honour and recognition in case of success.

Why, then, did these men choose to go? I’m not talking about Franklin, Amundsen, Scott, or Shackleton. I mean the men whose names have not come down to us, the hundreds or even thousands of men upon whose backs the poles of this earth were explored. I think the answer to this question is the reason why space exploration is inevitable. These men were along in part for the money, and in part for the fame, but mostly because the urge to explore is embedded so deep in all of us that the dark specter of death was no deterrent. Let me make my point all the more clear.
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