NASA shuts doors, pulls plug on shuttle Discovery

NASA powered down the space shuttle Discovery for a final time Friday , more than 28 years after the agency's retired fleet leader first came alive. The vehicle was "unplugged" inside Orbiter Processing Facility-1 (OPF-1) at the Kennedy Space Center in Florida.

The electrical shutdown, which came soon after technicians closed the shuttle's twin 60-foot long payload bay doors, was a milestone in Discovery's transition from a space-worthy orbiter to a museum exhibit. The shuttle, the oldest of NASA's remaining orbiters, is destined for display next spring at the Smithsonian National Air and Space Museum's Steven F. Udvar-Hazy Center in Virginia.

Discovery's cargo hold — which carried to orbit the Hubble Space Telescope and Ulysses solar probe along with modules for the International Space Station and more than a dozen satellites — was closed for what may be its last time. The Smithsonian plans to display the shuttle with its bay doors shut, at least initially.

The power down was much more permanent. Though Discovery's three electricity-generating fuel cells were reinstalled last week, they were first drained of all their reactants, and their feed lines were purged. Other than serving as an engineering example for researchers, they will never work again.

Since landing back on Earth after its 39th and final mission in March, Discovery has been carefully taken apart to preserve some of its components for future use while making the vehicle safe for public display. Its engines have been removed and replaced with replicas and its thrusters cleaned of their hazardous materials.

Inside its crew cabin, Discovery's waste collection system — otherwise known as its toilet — was removed, cleaned, and replaced, and its flight deck configured to appear ready for another mission, one that will never come. As with the fuel cells, the Smithsonian requested NASA keep Discovery as complete as possible so as to serve as a resource for future study.

Discovery is targeted to make one last flight in April 2012, though not under its own power and well within the atmosphere.

NASA Aids in Characterizing Super-Earth Atmosphere

A team of astronomers, including two NASA Sagan Fellows, has made the first characterizations of a super-Earth's atmosphere, by using a ground-based telescope. A super-Earth is a planet up to three times the size of Earth and weighing up to 10 times as much. The findings, reported in the Dec. 2 issue of the journal Nature, are a significant milestone toward eventually being able to probe the atmospheres of Earth-like planets for signs of life.

The team determined the planet, GJ 1214b, is either blanketed with a thin layer of water steam or surrounded by a thick layer of high clouds. If the former, the planet itself would have an icy composition. If the latter, the planet would be rocky or similar to the composition of Neptune, though much smaller.

"This is the first super-Earth known to have an atmosphere," said Jacob Bean, a NASA Sagan Fellow and astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "But even with these new measurements, we can't say yet what that atmosphere is made of. This world is being very shy and veiling its true nature from us."

GJ 1214b, first discovered in December 2009, is 2.7 times the size of Earth and 6.5 times as massive. Previous observations of the planet's size and mass demonstrated it has a low density for its size, leading astronomers to conclude the planet is some kind of solid body with an atmosphere.

The planet orbits close to its dim star, at a distance of 0.014 astronomical units. An astronomical unit is the distance between Earth and the sun, approximately 93 million miles. GJ 1214b circles too close to its star to be habitable by any life forms.

Bean and his team observed infrared light as the planet crossed in front of its star. During such transits, the star's light filters through the atmosphere. Gases absorb the starlight at particular wavelengths, leaving behind chemical fingerprints detectable from Earth. This same type of technique has been used to study the atmospheres of distant "hot Jupiters," or Jupiter-like planets orbiting close to their stars, and found gases like hydrogen, methane and sodium vapor.

In the case of the super-Earth, no chemical fingerprints were detected; however, this doesn't mean there are no chemicals present. Instead, this information ruled out some possibilities for GJ 1214b's atmosphere, and narrowed the scope to either an atmosphere of water steam or high clouds. Astronomers believe it's more likely the atmosphere is too thin around the planet to let enough light filter through and reveal chemical fingerprints.

"A steamy atmosphere would have to be very dense – about one-fifth water vapor by volume -- compared to our Earth, with an atmosphere that's four-fifths nitrogen and one-fifth oxygen with only a touch of water vapor," Bean said. "During the next year, we should have some solid answers about what this planet is truly like."

The team, which included Bean's co-authors -- Eliza Miller-Ricci Kempton, a NASA Sagan Fellow at the University of California in Santa Cruz, and Derek Homeier of the Institute for Astrophysics in Gottingen, Germany -- examined GJ 1214b using the ground-based Very Large Telescope at Paranal Observatory in Chile.

"This is an important step forward, narrowing our understanding of the atmosphere of this planet," said NASA Exoplanet Exploration Program Scientist Douglas Hudgins at NASA Headquarters in Washington. "Bizarre worlds like this make exoplanet science one of the most compelling areas in astrophysics today."

The Sagan Fellowship Program is administered by the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena. Its purpose is to advance the scientific and technical goals of NASA's Exoplanet Exploration Program. The program is managed for NASA by the Jet Propulsion Laboratory in Pasadena, Calif. Caltech manages JPL for NASA.

More information about NASA's planet-finding missions is online at:http://planetquest.jpl.nasa.gov . More information about NASA's Sagan Fellowship Program is at http://nexsci.caltech.edu/sagan .

Cassini Returns Images of Bright Jets at Enceladus

NASA's Cassini spacecraft successfully dipped near the surface of Saturn's moon Enceladus on Nov. 30. Though Cassini's closest approach took it to within about 48 kilometers (30 miles) of the moon's northern hemisphere, the spacecraft also captured shadowy images of the tortured south polar terrain and the brilliant jets that spray out from it.

Many of the raw images feature darkened terrain because winter has descended upon the southern hemisphere of Enceladus. But sunlight behind the moon backlights the jets of water vapor and icy particles. In some images, the jets line up in rows, forming curtains of spray.

The new raw images can be seen at http://saturn.jpl.nasa.gov/photos/raw/ .

The Enceladus flyby was the 12th of Cassini's mission, with the spacecraft swooping down around 61 degrees north latitude. This encounter and its twin three weeks later at the same altitude and latitude, are the closest Cassini will come to the northern hemisphere surface of Enceladus during the extended Solstice mission. (Cassini's closest-ever approach to Enceladus occurred in October 2008, when the spacecraft dipped to an altitude of 25 kilometers, or 16 miles.)

Among the observations Cassini made during this Enceladus flyby, the radio science subsystem collected gravity measurements to understand the moon's interior structure, and the fields and particles instruments sampled the charged particle environment around the moon.

About two days before the Enceladus flyby, Cassini also passed the sponge-like moon Hyperion, beaming back intriguing images of the craters on its surface. The flyby, at 72,000 kilometers (45,000 miles) in altitude, was one of the closest approaches to Hyperion that Cassini has made.

Scientists are still working to analyze the data and images collected during the flybys.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory manages the project for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

More Cassini information is available, at t http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .

Dark Reflections in the Southern Cross

NASA's Wide-field Infrared Survey Explorer, or WISE, captured this colorful image of the reflection nebula IRAS 12116-6001. This cloud of interstellar dust cannot be seen directly in visible light, but WISE's detectors observed the nebula at infrared wavelengths.

In images of reflection nebulae taken with visible light, clouds of dust reflect the light of nearby stars. The dust is warmed to relatively cool temperatures by the starlight and glows with infrared light, which WISE can detect. Reflection nebulae are of interest to astronomers because they are often the sites of new star formation.

The bright blue star on the right side of the image is the variable star Epsilon Crucis. In the Bayer system of stellar nomenclature, stars are given names based on their relative brightness within a constellation. The Greek alphabet is used to designate the star's apparent brightness compared to other stars in the same constellation. "Alpha" is the brightest star in the constellation, "beta" the second brightest, and so on. In this case, "epsilon" is the fifth letter of the Greek alphabet, so Epsilon Crucis is the fifth brightest star in the constellation Crux.

Crux is a well-known constellation that can be easily seen by observers in the Southern Hemisphere and from low northern latitudes. Also known as the Southern Cross, Crux is featured in many country's flags, including Australia, Brazil and New Zealand (although New Zealand's flag does not include Epsilon Crucis).

The colors used in this image represent specific wavelengths of infrared light. The blue color of Epsilon Crucis represents light emitted at 3.4 and 4.6 microns. The green-colored star seen beside Epsilon Crucis is emitting light at 12 microns. This star is IRAS 12194-6007, a carbon star that is near the end of its lifecycle. Since the infrared wavelengths emitted by this star are longer than those from Epsilon Crucis, it is cooler. The green and red colors seen in the reflection nebula represent 12- and 22-micron light coming from the nebula's dust grains warmed by nearby stars.

Lunar Impact May Impact Lunar Science For Years To Come

The lunar rocks brought back to Earth by the Apollo astronauts were found to have very little water, and were much drier than rocks on Earth. An explanation for this was that the moon formed billions of years ago in the solar system's turbulent youth, when a Mars-sized planet crashed into Earth. The impact stripped away our planet's outer layer, sending it into orbit. The pieces later coalesced under their own gravity to form our moon. Heat from all this mayhem vaporized most of the water in the lunar material, so the water was lost to space.

However, there was still a chance that water might be found in special places on the moon. Due to the moon's orientation to the sun, scientists theorized that deep craters at the lunar poles would be in permanent shadow and thus extremely cold and able to trap volatile material, like water as ice perhaps delivered there by comet impacts or chemical reactions with hydrogen carried by the solar wind.

In October 9, 2009, NASA's LCROSS (Lunar Crater Remote Observation and Sensing Satellite) was intentionally crashed into the Cabeus crater near the lunar south pole. The idea was to kick up debris from the bottom of the crater so its composition could be analyzed. LCROSS hit at over 9,000 kilometers (5,600 miles) per hour, sending up a plume of material over 19 kilometers (12 miles) high.

"Seeing mostly pure water ice grains in the plume means water ice was somehow delivered or chemical processes are causing ice to accumulate in large quantities," said Anthony Colaprete, LCROSS project scientist and principal investigator at NASA's Ames Research Center, Moffett Field, Calif. "Furthermore, the diversity and abundance of certain materials called volatiles in the plume, suggest a variety of sources, like comets and asteroids, and an active water cycle within the lunar shadows."

LCROSS was a companion mission to NASA's Lunar Reconnaissance Orbiter (LRO) mission. The two missions were designed to work together, and support from LRO was critical to the success of LCROSS. During impact, LRO, which is normally looking at the lunar surface, was tilted toward the horizon so it could observe the plume. Shortly after LCROSS hit the moon, LRO flew past debris and gas from the impact while its instruments collected data.

"LRO assisted LCROSS in two primary ways - selecting the impact site and confirming the LCROSS observations," said Gordon Chin of NASA's Goddard Space Flight Center, Greenbelt, Md., LRO associate project scientist.

"Since observatories on Earth were also planning to view the LCROSS impact, there were a lot of constraints on the location - the impact plume had to rise out of the crater and into sunlight, and it had to be visible from Earth," said Chin.

"Originally, the LCROSS team was going with a site farther north than the Cabeus crater, because it was better for Earth visibility," said Chin. "However, LEND revealed that the area did not have a high hydrogen concentration, but Cabeus did. Also, Diviner showed that Cabeus was one of the coldest sites, and LOLA indicated it was in permanent shadow. So, we were able to influence the decision to aim for Cabeus farther south -- while it was a little less visible from Earth, Cabeus was ultimately better for what we were trying to find."

The Diviner instrument aboard the Lunar Reconnaissance Orbiter was built and is managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif. Temperature maps from LRO's Diviner instrument were also crucial to identify where the coldest places were.

David Paige, principal investigator of the Diviner instrument from the University of California, Los Angeles, used temperature measurements of the lunar south pole obtained by Diviner to model the stability of water ice both at and near the surface.

"The temperatures inside these permanently shadowed craters are even colder than we had expected. Our model results indicate that in these extreme cold conditions, surface deposits of water ice would almost certainly be stable," said Paige, "but perhaps more significantly, these areas are surrounded by much larger permafrost regions where ice could be stable just beneath the surface."

"We conclude that large areas of the lunar south pole are cold enough to trap not only water ice, but other volatile compounds (substances with low boiling points) such as sulfur dioxide, carbon dioxide, formaldehyde, ammonia, methanol, mercury and sodium," Paige added.

A UCLA graduate student and Diviner team member, Paul Hayne, was monitoring the data in real-time as it was sent back from Diviner.

"During the flyby 90 seconds after impact, all seven of Diviner's infrared channels measured an enhanced thermal signal from the crater. The more sensitive of its two solar channels also measured the thermal signal, along with reflected sunlight from the impact plume. Two hours later, the three longest wavelength channels picked up the signal, and after four hours only one channel detected anything above the background temperature."

Scientists were able to learn two things from these measurements: first, they were able to constrain the mass of material that was ejected outwards into space from the impact crater; second, they were able to infer the initial temperature and make estimates about the effects of ice in the soil on the observed cooling behavior.

Another LRO instrument, the Lyman-Alpha Mapping Project (LAMP), used data on the gas cloud to confirm the presence of the gases molecular hydrogen, carbon monoxide and atomic mercury, along with smaller amounts of calcium and magnesium, also in gas form.

"We had hints from Apollo soils and models that the volatiles we see in the impact plume have been long collecting near the moon's polar regions," said Randy Gladstone, LAMP acting principal investigator, of Southwest Research Institute in San Antonio. "Now we have confirmation."

"The detection of mercury in the soil was the biggest surprise, especially that it's in about the same abundance as the water detected by LCROSS," said Kurt Retherford, LAMP team member, also of Southwest Research Institute.

"The observations by the suite of LRO and LCROSS instruments demonstrate the moon has a complex environment that experiences intriguing chemical processes," said Richard Vondrak, LRO project scientist at NASA Goddard. "This knowledge can open doors to new areas of research and exploration."

LCROSS launched with LRO aboard an Atlas V rocket from Cape Canaveral, Fla., on June 18, 2009.

The research was funded by NASA's Exploration Systems Missions Directorate at NASA Headquarters in Washington. LRO was built and is managed by NASA's Goddard Space Flight Center in Greenbelt, Md. LCROSS is managed by NASA's Ames Research Center, Moffett Field, Calif. LAMP was developed by the Southwest Research Institute in San Antonio, Texas; LOLA was built by NASA Goddard; LROC was provided by Arizona State University, Tempe; LEND was provided by Institute for Space Research, Moscow; The Diviner instrument was built and is managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif. UCLA is the home institution of Diviner's principal investigator.

For more information on Diviner, visit: http://diviner.ucla.edu.

Spiral Extraordinaire

Scientists have yet to discover what caused the strange spiral structure. Nor do they know why it glows. The glow may be caused by light reflected from nearby stars. As for the spiral itself, current supposition is that this is the result of a star in a binary star system entering the planetary nebula phase, when its outer atmosphere is ejected. Given the expansion rate of the spiral gas, a new layer must appear about every 800 years, a close match to the time it takes for the two stars to orbit each other. The above image was taken in near-infrared light by the Hubble Space Telescope.

Observe the Moon

This photograph shows the Laser Ranging Facility at the Geophysical and Astronomical Observatory at NASA's Goddard Spaceflight Center in Greenbelt, Md. The observatory helps NASA keep track of orbiting satellites. In this image, the lower of the two green beams is from the Lunar Reconnaissance Orbiter's dedicated tracker. The other laser originates from another ground system at the facility. Both beams are pointed at the moon -- specifically at LRO in orbit around the moon.

Crew Sets Up Hardware, Prepares for Soyuz Move

With Expedition 24 recently expanded to its full crew complement of six, the International Space Station’s residents tackled a variety of science and maintenance tasks Tuesday.

Flight Engineers Doug Wheelock, Shannon Walker and Fyodor Yurchikhin, who arrived at the station on the Soyuz TMA-19 spacecraft Thursday, participated in familiarization briefings with the crew members who welcomed them aboard -- Commander Alexander Skvortsov and Flight Engineers Mikhail Kornienko and Tracy Caldwell Dyson. The three new flight engineers also had an hour of free time set aside to study the layout of their orbital home for the next five-and-a-half months and learn to move about in its large habitable space.

Working in the Destiny laboratory, Wheelock and Walker began installing and outfitting the Window Observation Research Facility, a rack surrounding the lab’s 20-inch window. This rack will serve as an attachment point for cameras and scanners to be mounted in the window and provides power and data transfer capabilities for those instruments.

Caldwell Dyson performed her third session with an experiment that studies changes in the astronauts’ aerobic capacity during long-duration spaceflight. NASA is interested in tracking these changes because a reduction in maximum oxygen uptake directly impacts a crew member’s ability to perform strenuous activities such as spacewalks or emergency operations.

first Imager full-disk infrared image of the Earth

Operational Environmental Satellite – GOES-15 – took its first Imager full-disk infrared image of the Earth on April 26 starting at 1730 UTC (1:30 p.m. EDT). Each of the five Imager spectral bands are shown. There is one visible band and four infrared bands (shortwave window, water vapor, longwave window and a CO2 sensitive band)

The Sounder is another instrument on GOES-15 which also took Infrared images of the Earth. The Sounder is designed to provide data from which atmospheric temperature and moisture profiles, surface and cloud-top temperatures, and ozone distribution can be deduced by mathematical analysis.

GOES-15 also provides visible images of Earth. On April 6, GOES-15 captured its first visible image of Earth.

NASA Goddard Shoots the Moon to Track LRO

On certain nights, an arresting green line pierces the sky above NASA's Goddard Space Flight Center in Greenbelt, Md. It's a laser directed at the moon, visible when the air is humid. No, we're not repelling an invasion. Instead, we're tracking our own spacecraft.

28 times per second, engineers at NASA Goddard fire a laser that travels about 250,000 miles to hit the minivan-sized Lunar Reconnaissance Orbiter (LRO) spacecraft moving at nearly 3,600 miles per hour as it orbits the moon.

The first laser ranging effort to track a spacecraft beyond low-Earth orbit on a daily basis produces distance measurements accurate to about four inches (10 centimeters). For comparison, the microwave stations tracking LRO measure its range to a precision of about 65 feet (20 meters).

"Current lunar maps are not as accurate as we’ll need to return people safely to the moon," said Ronald Zellar of NASA Goddard, team lead for the LRO laser ranging system. "In order to make an accurate map, first you need to know where you are. Knowing the precise range to LRO is necessary for its instruments to produce much more accurate maps, with errors reduced to the size of humans or rovers."

"A further benefit of laser ranging to LRO is that it can improve knowledge of the moon's orientation and gravity, which are central to understanding its interior structure and to precision navigation," said Gregory Neumann, a Geophysicist at NASA Goddard.
Engineers use a telescope at the ground station on the Goddard campus to direct laser pulses toward LRO. The range to LRO is calculated by measuring how long it took the laser to reach the spacecraft.

The laser ranging to LRO is one way, meaning that the laser is directed at LRO, which records the time of arrival and sends the data back to ground stations on Earth by its radio telemetry link. This is the first time repeated, one-way tracking has been used for spacecraft ranging. Typical satellite laser ranging, used for spacecraft in low-Earth orbit, is two way, meaning the laser is simply reflected off the spacecraft and the time of flight recorded when it returns to the ground.

The advantage of LRO's one-way system is that a less expensive, lower-power laser system can be used -- especially important since the distance to LRO is hundreds of times greater than that to most Earth-orbiting spacecraft. Also, only a small receiver is needed on the spacecraft instead of a large retro-reflector array.

LRO's laser tracking presents unique challenges, however. First, there's the issue of avoiding interference. The laser pulses from Earth are received by a small telescope on LRO and transferred to the spacecraft’s laser altimeter instrument. The detector on this instrument performs double-duty, detecting both the laser ranging pulses as well as the pulses from its own laser reflected off the lunar surface. The instrument’s laser is used to build three-dimensional (topographic) maps of the lunar landscape and those pulses could hit the detector at the same time as the laser ranging pulses from Earth, confusing the data. So the pulses from Earth have to be carefully timed to avoid interfering with the instrument’s operation. Since the instrument sends laser pulses 28 times per second to the lunar surface, the laser ranging pulses are sent at the same rate but shifted in time to avoid interference. "It's like shooting at a spinning coin from a mile away and being able to hit it on the edge as it spins," said Neumann.

Another challenge is precise time measurement. Since the range to LRO is calculated by measuring how long it took the laser to reach the spacecraft, any variations in the time measurements will produce variations in the range estimates. LRO has a timing system that uses a crystal oscillator -- the heart of which is a vibrating crystal -- to measure time precisely. The oscillator is accurate to one part in a trillion over an hour. However, the rate at which the crystal vibrates changes with temperature, so the crystal is housed in a small oven which must be carefully controlled to maintain a stable temperature.

Then there's the difficulty of hitting a moving target. Since LRO is constantly moving in its orbit, the ground station must fire the laser pulses at a point in front of the spacecraft to compensate for the spacecraft's motion while the pulse is in-flight toward the moon. This is one of the reasons why LRO still relies on the traditional microwave tracking systems. They need the position of the spacecraft to know where to point the laser. The laser spot is 12 miles wide when it gets to the moon. Although this seems large on a human scale, it’s small in space and it would be easy to miss a tiny spacecraft moving 3,600 miles per hour. Even though the precision isn’t as great, without the microwave tracking system, the laser ranging system won’t work. This requires the LRO Mission Operations Center to track, predict, and communicate the position of the spacecraft to the laser ranging ground station.

Finally, there's the problem of bad weather; specifically, clouds. The laser can't penetrate thick cloud cover, so laser ranging is not available in those situations. Fortunately, there's plenty of opportunity to collect data over the course of LRO's one-year mission. "We're ranging to LRO whenever the moon is visible, 24 hours a day, 7 days a week," said Jan McGarry of NASA Goddard, ground system lead for laser ranging.

"Two-way satellite laser ranging (SLR) was developed at NASA Goddard in the 1960s," adds McGarry. "Since then, SLR has become a global effort, with about 30 countries participating and about 40 satellites carrying laser reflectors. NASA has eight SLR stations around the world, and Goddard is responsible for them. NASA is part of the global International Laser Ranging Service, an organization that provides a coordinated administration for all participating SLR stations and analysis centers." LRO's laser ranging effort is funded by the LRO project.

Learning How Materials Work in Space to Make Them Better on Earth

What's about the size of a large refrigerator, weighs a ton and may help pave the way for new and improved metals or glasses here on Earth?

It's the Materials Science Research Rack -- a new laboratory on board the International Space Station.

This facility will allow researchers to study a variety of materials -- including metals, alloys, semiconductors, ceramics, and glasses to see how the materials form, and learn how to control their properties. The results from experiments conducted in the facility could lead to the development of materials with improved properties on Earth.

Materials science research is a multidisciplinary endeavor studying the relationships between the processing conditions and properties of materials. The research rack -- measuring 6 feet high, 3.5 feet wide and 40 inches deep -- will provide a powerful, multi-user materials science laboratory in a microgravity, or near weightless, environment. Researchers can benefit from studying materials in space because they can isolate the fundamental heat and mass transfer processes involved that are frequently masked by gravity on the ground.

The research rack will provide hardware to control the thermal, environmental and vacuum conditions of experiments; monitor experiments with video; and supply power and data handling for specific experiment instrumentation.

"Materials science is an integral part of our everyday life," said Sandor Lehoczky, project scientist for the rack at NASA's Marshall Space Flight Center in Huntsville, Ala. "The goal of materials processing in space is to develop a better understanding of how processing affects materials properties without the complication of gravity causing density effects on the processes. With this knowledge, reliable predictions can be made about the conditions required on Earth to achieve improved materials."

The Materials Science Research Rack is an automated facility with two different furnace inserts in which sample cartridges will be processed to temperatures up to 2,500 degrees Fahrenheit. Initially, 13 sample cartridge assemblies will be processed, each containing mixtures of metal alloys. The cartridges are placed -- one at a time -- inside the furnace insert for processing. Once a cartridge is in place, the experiment can be run by automatic command or conducted via telemetry commands from the ground. Processed samples will be returned to Earth for evaluation and comparison of their properties to samples similarly processed on the ground.

The research rack was launched to the space station aboard space shuttle Discovery on August 28. It was installed in the U.S. Destiny Laboratory Sept. 2. The development of the rack was a cooperative effort between NASA and the European Space Agency. The rack accommodates the European Space Agency’s Materials Science Laboratory -- designed to provide controlled, materials processing conditions and advanced diagnostics. The Materials Science Laboratory has the capability to handle different furnace inserts. Metallurgical research will be conducted in the laboratory to gain a better understanding of industrial metallurgical processes, such as casting, welding and other advanced melting processes.

Kepler and the Search for Life in Our Galaxy

There are so many stars in our galaxy that even if planets with complex life (animals and plants) are rare – say one for every billion stars – there could still be dozens here in the Milky Way. But we are just beginning to learn about worlds beyond our solar system, called exoplanets, so we really don't have a good idea of what the chances are for advanced life. That's where NASA's Kepler mission comes in.

Currently, we have only one example of complex life –- our own. So we have to use conditions that give rise to this kind of life when we go looking for it elsewhere in the Universe. Essential ingredients in the recipe for life as we know it include liquid water; an energy source, such as sunlight or chemicals from volcanic activity; and a supply of raw materials in the form of critical elements like carbon, oxygen, hydrogen, and nitrogen, to name just a few. The most likely places where all the ingredients will be present are rocky planets, like Earth, that are within the habitable zone of their parent stars.

The habitable zone is where the temperature is just right for liquid water to exist on the surface of an exoplanet. If the planet is too close to its star, it will be too hot, and you'll end up with a world like Venus, where the oceans have boiled away. Too far away, however, and you get something like Mars, where most, if not all, of the water on the surface is frozen.

The Kepler mission seeks to detect Earth-like, i.e., rocky planets in our galaxy within the habitable zone of their parent stars, by looking for planetary transit events. These are situations where the planet passes in front of its star as seen from our point of view, slightly dimming the star's brightness. Since planetary transit events are fleeting, and it is unknown how common they may be, Kepler will continuously observe some 100,000 sun-like stars (in about 100 square degrees of the sky in the Cygnus region) for four years.


Observing planetary transits is challenging, because the brightness changes are exceedingly small. For example, Earth is about one-hundredth the diameter of the sun, so from an alien point of view, when Earth passes in front of the sun, it obscures only a tiny area on the solar disk -- just one ten-thousandth. An alien watching Earth transit the sun would see our star's brightness drop by just one part in ten thousand. We expect similar faint eclipses when searching for Earth-like planets around sun-like stars. To detect such tiny changes in brightness, Kepler will be able to observe a brightness change as small as one part in one hundred thousand.

Other challenges for Kepler are brightness changes that arise from a natural variation within the star itself, rather than from a transiting planet. If a brightness change repeats at regular intervals, it's more likely to be from an exoplanet, since its orbit will make it transit at the same periods. Scientists with the mission will need to see the same change at least twice before it's considered a possible exoplanet. Since the mission has a limited time to make its observations, if a transit takes more than a year to repeat, it will be difficult to confirm as an exoplanet.

We can analyze a planetary transit event to discover basic characteristics of the planet. A large planet will block more starlight than a small one, so the size of the planet can be estimated by how much the star dims during the transit. A planet close to its star zips around it faster than one farther away, so the time between transits will give us an approximate distance of the planet from its star.

The planet will also tug at the star with its gravity. Much as the siren of a speeding ambulance changes pitch as it passes by – higher when it's moving closer, and lower when it's moving away -- this gravitational pull will cause the colors (spectrum) of the star's light to shift slightly – more blue if the star is moving toward us, more red if the star is moving away. Astronomers can observe this color shift with instruments that separate the star's light into its component colors, called its spectrum. By observing the amount of color shift in the star's spectrum, astronomers can get the mass of the planet relative to its parent star – more massive planets have a greater pull and will cause a larger color shift.

Most exoplanet detections so far have been made using this spectral shift. Such detections, however, tend to favor massive planets (about Jupiter’s size or larger). With current technology, it's extremely difficult to detect Earth-sized planets using this technique.

Kepler will also be used to make discoveries about the stars themselves. There are many stars that are binaries (double stars). These binaries may exhibit eclipses. The Kepler mission data analysis program has a pipeline data processing that can discriminate the eclipsing binaries among the stars observed and will be analyzed accordingly. Binary stars, including cataclysmic variables (e.g., exploding stars such as novae) and intrinsic variable stars, including pulsating variables, that are observed with the Kepler satellite will present unprecedented opportunities to further astrophysical research.

The Kepler observatory was placed in an Earth-following orbit March 6, 2009. This mission has been conceived by William Borucki and Dave Koch of NASA Ames Research Center, Moffett Field, Calif., and developed at NASA Ames.

Kepler is a NASA Discovery mission. NASA Ames is the home organization of the science principal investigator, and is responsible for the ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory, Pasadena, Calif. manages the Kepler mission development. Ball Aerospace & Technologies Corp. of Boulder, Colo., is responsible for developing the Kepler flight system and supporting mission operations.