NASA Research Team Reveals Moon Has Earth-Like Core

Dwayne Brown

Headquarters, Washington                          

 

Janet Anderson

Marshall Space Flight Center, Huntsville, Ala.

WASHINGTON – State-of-the-art seismological techniques applied to Apollo-era data suggest our moon has a core similar to Earth's.

Uncovering details about the lunar core is critical for developing accurate models of the moon's formation. The data sheds light on the evolution of a lunar dynamo -- a natural process by which our moon may have generated and maintained its own strong magnetic field.

The team's findings suggest the moon possesses a solid, iron-rich inner core with a radius of nearly 150 miles and a fluid, primarily liquid-iron outer core with a radius of roughly 205 miles. Where it differs from Earth is a partially molten boundary layer around the core estimated to have a radius of nearly 300 miles. The research indicates the core contains a small percentage of light elements such as sulfur, echoing new seismology research on Earth that suggests the presence of light elements -- such as sulfur and oxygen -- in a layer around our own core.

The researchers used extensive data gathered during the Apollo-era moon missions. The Apollo Passive Seismic Experiment consisted of four seismometers deployed between 1969 and 1972, which recorded continuous lunar seismic activity until late-1977.

"We applied tried and true methodologies from terrestrial seismology to this legacy data set to present the first-ever direct detection of the moon's core," said Renee Weber, lead researcher and space scientist at NASA's Marshall Space Flight Center in Huntsville, Ala.

In addition to Weber, the team consisted of scientists from Marshall; Arizona State University; the University of California at Santa Cruz; and the Institut de Physique du Globe de Paris in France. Their findings are published in the online edition of the journal Science.

The team also analyzed Apollo lunar seismograms using array processing, techniques that identify and distinguish signal sources of moonquakes and other seismic activity. The researchers identified how and where seismic waves passed through or were reflected by elements of the moon's interior, signifying the composition and state of layer interfaces at varying depths.

Although sophisticated satellite imaging missions to the moon made significant contributions to the study of its history and topography, the deep interior of Earth's sole natural satellite remained a subject of speculation and conjecture since the Apollo era. Researchers previously had inferred the existence of a core, based on indirect estimates of the moon's interior properties, but many disagreed about its radius, state and composition.

A primary limitation to past lunar seismic studies was the wash of "noise" caused by overlapping signals bouncing repeatedly off structures in the moon's fractionated crust. To mitigate this challenge, Weber and the team employed an approach called seismogram stacking, or the digital partitioning of signals. Stacking improved the signal-to-noise ratio and enabled the researchers to more clearly track the path and behavior of each unique signal as it passed through the lunar interior.

"We hope to continue working with the Apollo seismic data to further refine our estimates of core properties and characterize lunar signals as clearly as possible to aid in the interpretation of data returned from future missions," Weber said.

Future NASA missions will help gather more detailed data. The Gravity Recovery and Interior Laboratory, or GRAIL, is a NASA Discovery-class mission set to launch this year. The mission consists of twin spacecraft that will enter tandem orbits around the moon for several months to measure the gravity field in unprecedented detail. The mission also will answer longstanding questions about Earth's moon and provide scientists a better understanding of the satellite from crust to core, revealing subsurface structures and, indirectly, its thermal history.

NASA and other space agencies have been studying concepts to establish an International Lunar Network -- a robotic set of geophysical monitoring stations on the moon -- as part of efforts to coordinate international missions during the coming decade.

For more information about NASA science exploration missions, visit http://www.nasa.gov/topics/moonmars.

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Andromeda’s Once and Future Stars

Two European Space Agency observatories combined forces to show the Andromeda Galaxy in a new light. Herschel sees rings of star formation in this, the most detailed image of the Andromeda Galaxy ever taken at infrared wavelengths, and XMM-Newton shows dying stars shining X-rays into space.

ESA’s Herschel and XMM-Newton space observatories targeted the Andromeda Galaxy, the nearest large spiral galaxy, which like our own Milky Way contains several hundred billion stars. This is the most detailed far-infrared image of the Andromeda Galaxy ever taken and clearly shows that more stars are on their way.

In this image, Herschel’s infrared image of the Andromeda Galaxy shows rings of dust that trace gaseous reservoirs where new stars are forming and XMM-Newton’s X-ray image shows stars approaching the ends of their lives. Both infrared and X-ray images convey information impossible to collect from the ground because these wavelengths are absorbed by Earth’s atmosphere.

For more information and images, visit the ESA site.

Image Credit: ESA/Herschel/PACS/SPIRE/J.Fritz, U.Gent/XMM-Newton/EPIC/W. Pietsch, MPE

Making the Grade: Arnold Elementary School [Dispatches from Antarctica]

By John Ohab

The series features Air Force Lt. Col. Ed Vaughan’s first-hand experiences on OPERATION: DEEP FREEZE, the Defense Department’s support of National Science Foundation research in Antarctica.

In our effort to engage students and teachers, we asked students in Ms. Vogt’s class at Arnold Elementary School in Arnold, MD, to submit their top questions about life in Antarctica. As you probably guessed, bugs, penguins, and food were on their minds.

Stayed tuned for two more question and answer series from elementary and high school students at the Department of Defense Education Activity. Please feel free to let us know what you think in the comment section. Off we go!

1. How did you prepare for your trip to Antarctica?

Lt. Col. Vaughan: The first thing I did to prepare was complete Arctic survival training. Even though I worked in Antarctica, surviving in the Arctic had many similarities.

I did this training in Greenland in 1992. It was known as barren land Arctic Survival Training because there are no trees and few if any animals in Antarctica to help with survival. In that training, we learned how to fashion living quarters out of the snow and ice. We also learned about hydration and not overheating by working too hard because that might lead to sweating underneath the heavy gear and later hypothermia.

In order to specifically get ready for Antarctica, however, I was left to my own devices. For that, I talked to people who had been there many times before. I asked them what they recommended I bring to supplement the basic cold weather gear issued by the government.

Most people discussed having a good water bottle that I could refill and wash easily. They mentioned sunscreen, yes even in a cold place the sun can burn any exposed skin like face and neck. They also recommended I bring lip balm and skin moisturizer for the extremely dry air. Some were able to suggest particular brands of long underwear and glove and sock liners that are designed for extreme cold regions like this. Again, the key is to wick away excess moisture from the skin, while maintaining warmth.

2. What do you eat?

Lt. Col. Vaughan: These days, both the food and accommodations are quite good. There’s a PhD nutritionist in charge of food service at McMurdo. Fresh meals are cooked every day. There are always dishes with meat of some kind, plus vegetarian style dishes for those who do not eat meat. When the C-17s are flying frequently, to and from New Zealand, then we tend to have more fresh eggs and vegetables, called “freshies”. When there are longer times between flights, then we may eat egg mix or frozen or canned produce.

Here is a video all about the cuisine we enjoy in Antarctica courtesy of Dr. Jennifer Jabs, Culinary Manager for all of US Antarctic Program:

3. How do you travel in Antarctica? Is it a place where people could live?

Lt. Col. Vaughan: Excellent question. We travel by airplane, helicopter, and overland using a variety of tracked and wheeled vehicles. In the old days, people traveled by dog-sled, and occasionally by horse, but that practice has been banned in Antarctica due to the risk of dogs and animals carrying diseases that might spread to local species.

To give you a sense of the travel conditions, here is a video of an inbound flight to Antarctica as viewed from several different people with different perspectives:

People do live in Antarctica at the various science stations and remote outposts scattered about. However, these people require outside support. Food and fuel from other places must be brought in to support them. These supplies are brought in via airplane, tractor, overland traverse and other methods.

There are some expeditions who attempt “unsupported” crossings of the continent, meaning they will carry all their supplies with them and not require outside help. However, these are very difficult treks and can result in calls for emergency help when they fail.

4. Are there bugs in Antarctica? How do they survive?

Lt. Col. Vaughan: That is a loaded question and took me a long time to ponder. I think you probably mean garden variety bugs like flies, mosquitoes, bees, and spiders. The answer to that is no. Although some bugs will accidentally stow away on an airplane, once they hit the sub zero temperatures of Antarctic air, they usually perish. If that doesn’t do them in, then the lack of food, lack of mates, and poor conditions for reproduction will eventually wipe them out. Taken another way, though, there are many “bugs” in Antarctica.

Paleontologically and Archeologically speaking: scientists have recently unearthed evidence, 45 million-year old turtle bones actually, that suggest the coldest continent was once a tropical rain forest with many species of bugs. According to scientists working in Seymour Island, Antarctica was once connected to New Guinea and Australia. During the Eocene Epoch, roughly 50 million years ago, the combined continent known as Gondwanaland, supported a tropical rain forest. Given the diversity of life found in such a climate, it is reasonable to expect that there might be ancient bug remains scattered throughout Antarctica. Maybe someone in your class will be among the first scientists to find proof.

1st Lt Languuth, Flight Nurse at McMurdo Station: The seasonal cold at McMurdo Station is lovingly referred to as “The Crud.” Annually, as the population grows on station, the amount of cases seen at the clinic increases, both because of the number of people exposed as well as the close living quarters and multiple common areas, including the galley. Other diseases or infectious processes are magnified by these conditions as well. So yes, some “bugs” are alive and well here.

5. Penguins…are they friendly? Seen any eaten by leopard seals?

Lt. Col. Vaughan: Of course penguins are friendly—to each other. But they can also be rather cantankerous and territorial too. Per international conventions and rules, none of us are permitted to approach penguins or other animals for any reason. Only specifically authorized scientists can do that in the interest of scientific research.

So I offer this excellent site all about penguins in Antarctica. It has downloads for teachers and students, stories, pictures, videos, and places to send postcards. It is www.PenguinScience.com. And if I happen to see a penguin chased and/or eaten by a Leopard Seal, I will film it and post it on this website. To the best of my knowledge, there are no vegetarian Leopard Seals, so penguins look out!

6. Have you had any encounters with dangerous animals?

Lt. Col. Vaughan: Although in past seasons, I’ve seen Orcas in the waters around McMurdo Station, I’ve had no direct encounters with them. Whether or not they are “dangerous” is a matter of perspective and opinion.

Certainly they are capable of eating a human, so I would prefer to watch them from a distance. Leopard seals are dangerous to penguins and from a small fish perspective, lots of animals might be dangerous. Species such as Polar Bears, Musk Oxen, Arctic Fox are all found in the Arctic and not Antarctica.

I think the only universally dangerous species in Antarctica, and after watching Happy Feet my daughter might agree, is humans.

7. Based on your data, what is happening with global warming? What are you studying?

Lt. Col. Vaughan: As part of the military here, my role is to support the scientists in their work. We provide airplanes and ships to help move people, fuel, and cargo to support scientific research. So while I don’t have a particular science project of my own, like you, I enjoy hearing about the work of the men and women here that we support. For more on recent findings related to global warming, I’d recommend visiting the National Science Foundation’s website.

Exoplanets, Dwarf Stars, Gamma-Ray Flashes, New Images Among NASA News Highlights At American Astronomical Society Meeting

Trent Perrotto

Headquarters, Washington     

WASHINGTON -- NASA researchers will present new findings on a wide range of space science topics during the meeting of the American Astronomical Society. The meeting runs Sunday, Jan. 9, through Thursday, Jan. 13, at the Washington State Convention and Trade Center, located at

800 Convention Place

in Seattle.

Media briefings during the conference will discuss new results on exoplanet research, dwarf stars, gamma-ray flashes and black holes. New images will be released from missions including the Hubble Space Telescope; the Wide-Field Infrared Survey Explorer, or WISE; the Chandra X-ray Observatory; and the Stratospheric Observatory for Infrared Astronomy, or SOFIA. NASA scientists and their colleagues who use NASA research capabilities will present noteworthy findings during scientific sessions that are open to registered journalists.

Registration is still open.

For a complete list of NASA-related news briefings at the meeting, visit http://www.nasa.gov/aas.

The website contains detailed information about how reporters can participate in the briefings, both on-site and remotely. The site will be updated throughout the week with additional information about NASA presentations.

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NASA Administrator Charles Bolden's Statement on the Shooting of Congresswoman Giffords

Michael Cabbage

Headquarters, Washington

James Hartsfield

Johnson Space Center

NASA Administrator Charles Bolden issued the following statement Saturday about the shooting in Tucson, Ariz., of U.S. Rep. Gabrielle Giffords and several others:

"We at NASA are deeply shocked and saddened by the senseless shooting of Representative Giffords and others at Saturday’s public event in Tucson. As a long-time supporter of NASA, Representative Giffords not only has made lasting contributions to our country, but is a strong advocate for the nation’s space program and a member of the NASA family. She also is a personal friend with whom I have had the great honor of working. We at NASA mourn this tragedy and our thoughts and prayers go out to Congresswoman Giffords, her husband Mark Kelly, their family, and the families and friends of all who perished or were injured in this terrible tragedy."

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The secret is out…now do you want to be friends?

by Christopher Zember, Deputy Director, Information Analysis Centers

No, we’re not talking about Facebook friends, but real friends, who have a problem to solve and simply don’t have time to sift through mountains of data to uncover the answer they need. If this sounds familiar, don’t worry – you have a friend in the Department of Defense (DOD) Information Analysis Centers (IACs).

IACs routinely provide tactical information straight to the Warfighter, through our growing network of “friends” – scientists, engineers, and other technical experts in various fields. We are also constantly uncovering new information through cutting edge studies and analysis. And the best part: up to 4 hours of research is free of charge.

Hosted by government, industry, and academia, with strategy and policy oversight coming from the Office of DoD’s Chief Technology Officer, the Centers offer research and analysis in a number of cutting edge fields: advanced materials; chemical, biological, radiological and nuclear defense; chemical propulsion; data and software analysis; information assurance; modeling and simulation; systems reliability and interoperability; military sensing; survivability/vulnerability; and weapon systems technology.

And IAC scope is continuing to expand, with planned new areas to include non-kinetic weapons, biometrics, medical research, cultural studies, and alternative energy.

What makes the IACs unique? Here’s what our customers are saying:

I like knowing I’ve consulted all available sources through one central contact at the IAC.

It’s the speed and ease of use; they’re the most efficient way I know to get results.

They understand their customers. When I call, I get an expert who understands my problem – often better than I do myself.

Over the last few years, the IACs started to work their way into the spotlight, having played an important role in a number of high-profile projects including improving the reliability and survivability of the MRAP (Mine Resistant Ambush Protected) vehicles, support for IED (Improvised Explosive Devise) defeat, and improving helicopter survivability.

For more information on these and other examples of where the IACs are supporting the Warfighter, check back on Armed with Science, where an IAC will be featured once a week for the next several weeks. And be sure to visit our website at: http://iac.dtic.mil.

IACs bring the “think tank” to the battlespace.

This article was sponsored by Police Technology.

32 Stringers Undergoing Modifications

Science technicians at NASA’s Kennedy Space Center in Florida now are modifying 32 support beams, called stringers, on space shuttle Discovery’s external fuel tank instead of 34. Teams have determined that modifications on two stringers are not needed because one stringer already is being repaired due to cracks found on Dec. 29 and the other is made with a stronger type of aluminum. Crews will fit pieces of metal, called radius blocks, over both edges of the stringers where they attach to the external tank’s thrust panel area. The radius blocks will increase the structural support of the stringers. The thrust panel areas are located at the attachment points between the tank and the solid rocket boosters, which see the most stress during the flight into orbit. The work is expected to be completed by the end of next week.

‪Repairs to four cracks on three stringers on the opposite side of the tank from Discovery that were discovered Dec. 29 began Monday and are expected to be completed by Friday. Technicians removed the stringers overnight and begin installing replacement stringer sections today. The repairs are similar to repairs made on cracks found on two stringers after Discovery's Nov. 5 launch attempt.

‪Teams also are performing scans on all of the tank’s stringers using a backscatter device, which bounces radiation off the tank allowing engineers to see below the foam insulation. Engineers at various NASA centers continue to analyze testing and imaging data. Preliminary results from this latest round of X-ray type image scans show no cracks in the stringers that have been scanned so far. Managers will meet again Thursday to determine whether radius block modifications are needed on the remaining stringers. Scans are expected to be completed this weekend.

‪‪The next available launch date for Discovery's STS-133 mission to the International Space Station remains Feb. 3 at the opening of a window that extends through Feb. 10.