WISE Mission

NASA's Wise Mission Finds First Trojan Asteroid Sharing Earth's Orbit
 
 
WASHINGTON -- 2011 July 27 -  Astronomers studying observations taken by NASA's Wide-field Infrared Survey Explorer (WISE) mission have discovered the first known "Trojan" asteroid orbiting the sun along with Earth.

Trojans are asteroids that share an orbit with a planet near stable points in front of or behind the planet. Because they constantly lead or follow in the same orbit as the planet, they never can collide with it. In our solar system, Trojans also share orbits with Neptune, Mars and Jupiter. Two of Saturn's moons share orbits with Trojans.

Scientists had predicted Earth should have Trojans, but they have been difficult to find because they are relatively small and appear near the sun from Earth's point of view.

"These asteroids dwell mostly in the daylight, making them very hard to see," said Martin Connors of Athabasca University in Canada, lead author of a new paper on the discovery in the 2011 July 28 issue of the journal Nature. "But we finally found one, because the object has an unusual orbit that takes it farther away from the sun than what is typical for Trojans. WISE was a game-changer, giving us a point of view difficult to have at Earth's surface."

The WISE telescope scanned the entire sky in infrared light from January 2010 to February 2011. Connors and his team began their search for an Earth Trojan using data from NEOWISE, an addition to the WISE mission that focused in part on near-Earth objects, or NEOs, such as asteroids and comets. NEOs are bodies that pass within 28 million miles (45 million kilometers) of Earth's path around the sun. The NEOWISE project observed more than 155,000 asteroids in the main belt between Mars and Jupiter, and more than 500 NEOs, discovering 132 that were previously unknown.

The team's hunt resulted in two Trojan candidates. One called 2010 TK7 was confirmed as an Earth Trojan after follow-up observations with the Canada-France-Hawaii Telescope on Mauna Kea in Hawaii.


The asteroid is roughly 1,000 feet (300 meters) in diameter. It has an unusual orbit that traces a complex motion near a stable point in the plane of Earth's orbit, although the asteroid also moves above and below the plane. The object is about 50 million miles (80 million kilometers) from Earth. The asteroid's orbit is well-defined and for at least the next 100 years, it will not come closer to Earth than 15 million miles (24 million kilometers).

                                         An animation showing the orbit is available at:

       http://www.nasa.gov/multimedia/videogallery/index.html?media_id=103550791


"It's as though Earth is playing follow the leader," said Amy Mainzer, the principal investigator of NEOWISE at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "Earth always is chasing this asteroid around."

A handful of other asteroids also have orbits similar to Earth. Such objects could make excellent candidates for future robotic or human exploration. Asteroid 2010 TK7 is not a good target because it travels too far above and below the plane of Earth's orbit, which would require large amounts of fuel to reach it.

"This observation illustrates why NASA's NEO Observation program funded the mission enhancement to process data collected by WISE," said Lindley Johnson, NEOWISE program executive at NASA Headquarters in Washington. "We believed there was great potential to find objects in near-Earth space that had not been seen before."

NEOWISE data on orbits from the hundreds of thousands of asteroids and comets it observed are available through the NASA-funded International Astronomical Union's Minor Planet Center at the Smithsonian Astrophysical Observatory in Cambridge, Mass.
JPL manages and operates WISE for NASA's Science Mission Directorate in Washington. The principal investigator, Edward Wright, is a professor at the University of California, Los Angeles. The mission was selected under NASA's Explorers Program, which is managed by the agency's Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah.

The spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

http://www.nasa.gov/images/content/575263main_pia14405-43_946-710.jpg

A Glimmer in the Eye of WISE

Asteroid 2010 TK7 is circled in green, in this single frame taken by NASA's Wide-field Infrared Survey Explorer, or WISE. The majority of the other dots are stars or galaxies far beyond our solar system.

Astronomers discovered this object -- the first known Earth Trojan asteroid -- after sifting through asteroid candidates identified by WISE.

This image was taken in infrared light at a wavelength of 4.6 microns in October 2010.


Image credit: NASA/JPL-Caltech/UCLA



For more WISE information visit:


http://www.nasa.gov/wise

 



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NASA's NEOWISE Completes Scan

 For Asteroids and Comets

A Family Portrait
During its one-year mission, NASA's Wide-field Infrared Survey Explorer, or WISE, mapped the entire sky in infrared light. Among the multitudes of astronomical bodies that have been discovered by the NEOWISE portion of the WISE mission are 20 comets.
› Full image and caption | Slide Show: NEOWISE: A Solar System Safari


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February 01, 2011

PASADENA, Calif. -- NASA's NEOWISE mission has completed its survey of small bodies, asteroids and comets, in our solar system. The mission's discoveries of previously unknown objects include 20 comets, more than 33,000 asteroids in the main belt between Mars and Jupiter, and 134 near-Earth objects (NEOs). The NEOs are asteroids and comets with orbits that come within 45 million kilometers (28 million miles) of Earth's path around the sun.

NEOWISE is an enhancement of the Wide-field Infrared Survey Explorer, or WISE, mission that launched in December 2009. WISE scanned the entire celestial sky in infrared light about 1.5 times. It captured more than 2.7 million images of objects in space, ranging from faraway galaxies to asteroids and comets close to Earth.

In early October 2010, after completing its prime science mission, the spacecraft ran out of the frozen coolant that keeps its instrumentation cold. However, two of its four infrared cameras remained operational. These two channels were still useful for asteroid hunting, so NASA extended the NEOWISE portion of the WISE mission by four months, with the primary purpose of hunting for more asteroids and comets, and to finish one complete scan of the main asteroid belt.


"Even just one year of observations from the NEOWISE project has significantly increased our catalog of data on NEOs and the other small bodies of the solar systems," said Lindley Johnson, NASA's program executive for the NEO Observation Program.


Now that NEOWISE has successfully completed a full sweep of the main asteroid belt, the WISE spacecraft will go into hibernation mode and remain in polar orbit around Earth, where it could be called back into service in the future.


In addition to discovering new asteroids and comets, NEOWISE also confirmed the presence of objects in the main belt that had already been detected. In just one year, it observed about 153,000 rocky bodies out of approximately 500,000 known objects. Those include the 33,000 that NEOWISE discovered.


NEOWISE also observed known objects closer and farther to us than the main belt, including roughly 2,000 asteroids that orbit along with Jupiter, hundreds of NEOs and more than 100 comets.

These observations will be key to determining the objects' sizes and compositions. Visible-light data alone reveal how much sunlight reflects off an asteroid, whereas infrared data is much more directly related to the object's size. By combining visible and infrared measurements, astronomers also can learn about the compositions of the rocky bodies -- for example, whether they are solid or crumbly. The findings will lead to a much-improved picture of the various asteroid populations.


NEOWISE took longer to survey the whole asteroid belt than WISE took to scan the entire sky because most of the asteroids are moving in the same direction around the sun as the spacecraft moves while it orbits Earth. The spacecraft field of view had to catch up to, and lap, the movement of the asteroids in order to see them all.


"You can think of Earth and the asteroids as racehorses moving along in a track," said Amy Mainzer, the principal investigator of NEOWISE at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "We're moving along together around the sun, but the main belt asteroids are like horses on the outer part of the track. They take longer to orbit than us, so we eventually lap them."


NEOWISE data on the asteroid and comet orbits are catalogued at the NASA-funded International Astronomical Union's Minor Planet Center, a clearinghouse for information about all solar system bodies at the Smithsonian Astrophysical Observatory in Cambridge, Mass. The science team is analyzing the infrared observations now and will publish new findings in the coming months.


When combined with WISE observations, NEOWISE data will aid in the discovery of the closest dim stars, called  brown dwarfs. These observations have the potential to reveal a brown dwarf even closer to us than our closest known star, Proxima Centauri, if such an object does exist. Likewise, if there is a hidden gas-giant planet in the outer reaches of our solar system, data from WISE and NEOWISE could detect it.

The first batch of observations from the WISE mission will be available to the public and astronomical community in April 2011.


"WISE has unearthed a mother lode of amazing sources, and we're having a great time figuring out their nature," said Edward (Ned) Wright, the principal investigator of WISE at UCLA.


JPL manages WISE for NASA's Science Mission Directorate at the agency's headquarters in Washington. The mission was competitively selected under NASA's Explorers Program, which NASA's Goddard Space Flight Center in Greenbelt, Md., manages. The Space Dynamics Laboratory in Logan, Utah, built the science instrument, and Ball Aerospace & Technologies Corp. of Boulder, Colo., built the spacecraft. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. JPL manages NEOWISE for NASA's Planetary Sciences Division. The mission's data processing also takes place at the Infrared Processing and Analysis Center.


More information is online at
http://www.nasa.gov/wise , http://wise.astro.ucla.edu and http://www.jpl.nasa.gov/wise .

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

Trent Perrotto 202-358-0321

Headquarters, Washington
trent.j.perrotto@nasa.gov

2011-031

 
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2010 November 17

WISE Captures a Glowing Cylinder in Space

Posted in: Astrophotos, Missions by Nancy Atkinson from UNIVERSETODAY.COM

NGC 1514, sometimes called the 'Crystal Ball' nebula shows a new double ring feature in an image from WISE. Image credit: NASA/JPL-Caltech/UCLA

It’s not like we’ve never seen the planetary nebula NGC 1514 before, but we’ve never seen it though WISE’s infrared eyes, until now. And in a stunning surprise, cylindrical rings appear to be encircling the dying star, like a neon-lit carousel, or perhaps like rolling tire surrounding a glowing blob. “I just happened to look up one of my favorite objects in our WISE catalogue and was shocked to see these odd rings,” said Michael Ressler, a member of the WISE science team at JPL. “This object has been studied for more than 200 years, but WISE shows us it still has surprises.

Space Station from the movie 2001: A Space Odyssey.

At first glance the rings look like the double-ringed space station in the movie 2001: A Space Odyssey. (Too bad the Bad Astronomer beat me to that likeness. He also compared it to a tuna can.)

Other people see different things in this image.

“I am reminded of the jellyfish exhibition at the Monterey Bay Aquarium — beautiful things floating in water, except this one is in space,” said Edward (Ned) Wright, the principal investigator of the WISE mission at UCLA, and a co-author of a paper on the findings, reported in the Astronomical Journal.

WISE was able to spot the rings for the first time because their dust is being heated and glows with the infrared light that WISE can detect. In visible-light images, the rings are hidden from view, overwhelmed by the brightly fluorescing clouds of gas.

Here’s what NGC 1514 looks like in visible light from a ground observatory:

NGC1514 in visible light. Image credit: Digitized Sky Survey/STScI

The object is actually a pair of stars, seen as a single dot at the center of the blue orb. One star is a dying giant somewhat heavier and hotter than our sun, and the other was an even larger star that has now contracted into a dense body called a white dwarf. As the giant star ages, it sheds some its outer layers of material. An inner shell of ejected material is seen in bright, light blues. An outer shell can also be seen in more translucent shades of blue.

This planetary nebula is also called the “Crystal Ball” nebula, and Ressler said although NGC 1514′s structure looks unique, is probably similar in overall geometry to other hour-glass nebulae, such as the Engraved Hourglass Nebula.

Planetary Nebula MyCn18: An Hourglass Pattern Around a Dying Star. Credit: Raghvendra Sahai and John Trauger (JPL), the WFPC2 science team, and NASA.

The structure looks different in WISE’s view because the rings are detectable only by their heat; they do not fluoresce at visible wavelengths, as do the rings in the other objects.

The WISE science team says that more oddballs like NGC 1514 are sure to turn up in the plethora of WISE data — the first batch of which will be released to the astronomical community in spring 2011.

Source: JPL

 

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2010 August 11

WISE Cryostat is Depleting

Posted in: Asteroids, Missions by Nancy Atkinson  from  UniverseToday.com

 

A Recent WISE image of the Small Magellanic Cloud

 Image credit: NASA/JPL-Caltech/WISE Team



NASA's Wide-field Infrared Survey Explorer, or WISE, is losing its cool. The spacecraft is running out of the frozen coolant needed to keep its heat-sensitive instrument chilled, and will only be in operation for 2-3 more months. While the spacecraft was designed to be rather short-lived – 7 to 10 months — it still is sad to see the mission winding down. But WISE has completed its primary mission, a full scan of the entire sky in infrared light, which was accomplished by July 17, 2010. The mission has taken more than 1.5 million snapshots so far, uncovering hundreds of millions of objects, including asteroids, stars and galaxies.

It has discovered more than 29,000 new asteroids to date, more than 100 near-Earth objects and 15 comets.

The telescope has two coolant tanks that keep the spacecraft's normal operating temperature at 12 Kelvin (minus 438 degrees Fahrenheit). The outer, secondary tank is now depleted, causing the temperature to increase. One of WISE's infrared detectors, the longest-wavelength band most sensitive to heat, stopped producing useful data once the telescope warmed to 31 Kelvin (minus 404 degrees Fahrenheit). The primary tank still has a healthy supply of coolant, and data quality from the remaining infrared detectors remains high.

WISE is continuing a second survey of about one-half the sky as originally planned. It’s possible the remaining coolant will run out before that scan is finished. Scientists say the second scan will help identify new and nearby objects, as well as those that have changed in brightness. It could also help to confirm oddball objects picked up in the first scan.

NASA is hoping to find more Near Earth Objects with WISE's remaining days of operations.
"WISE's prime mission was to do an infrared background map," said Lindley Johnson, program executive for the Near-Earth Objects Observation program at NASA, speaking at a workshop this week to define objectives for exploring asteroids. "But we realized in talking with scientists that it would also make a good asteroid detector by comparing images. It has done a good job of finding a lot of objects for us."

Source: NASA




May 24th, 2010 from  UniverseToday.com

WISE Covers the Heart and Soul of Infrared Astronomy

Written by Nancy Atkinson

The Heart and Soul Nebulae are seen in this infrared mosaic from NASA's Wide-field Infrared Survey Explorer, or WISE. Image credit: NASA/JPL-Caltech/UCLA

In about six months' time, NASA's WISE mission, the Wide-field Infrared Survey Explorer, has captured almost a million images, covering about three-quarters, or 30,000 square degrees, of the sky. At the 216th American Astronomical Society meeting today, astronomers released a new mosaic of two bubbling clouds in space, known as the Heart and Soul nebulae.

“This image actually has two hearts; one is a Valentine’s Day heart, and the other is a surgical heart that you have in your body,” said Ned Wright of the University of California, Los Angeles who presented the new picture. "This new image demonstrates the power of WISE to capture vast regions. We're looking north, south, east and west to map the whole sky."

To make this huge mosaic WISE stared at this region of space which lies about 6,000 light-years away in the constellation Cassiopeia, for 3.5 hours of total exposure time, taking 1,147 images.

Both these nebulae are massive star-making factories, marked by giant bubbles blown into surrounding dust by radiation and winds from the stars. The infrared vision of WISE allows it to see into the cooler and dustier crevices of clouds like these, where gas and dust are just beginning to collect into new stars.

WISE will complete its first map of the sky in July 2010, and then spend the next three months surveying much of the sky a second time, before the solid-hydrogen coolant needed to chill its infrared detectors runs dry. Wright said the first installment of the public WISE catalog will be released in summer 2011.
Wright marveled at how in the span of his career he has gone from observing in just 4 pixels to now observing with WISE in almost 4 million pixels.

“It’s been an amazing progress in IR astronomy, with cameras growing by a factor of a million in power in just a few decades,” he said.

http://www.universetoday.com/wp-content/uploads/2010/05/WISE-coverage.jpg

Screen shot from Wright's presentation at the AAS meeting showing how much of the sky WISE has covered. The small green box at left middle shows the area of the Heart and Soul nebulae.


Spotting NEO's (Near Earth Objects)

One goal of the WISE mission is to study asteroids throughout our solar system and to find out more about how they vary in size and composition. Infrared helps with this task because it can get better size measurements of the space rocks than visible light.

So far, WISE has observed more than 60,000 asteroids, most of which lie in the main belt, orbiting between Mars and Jupiter. About 11,000 of these objects are newly discovered, and about 50 of them belong to a class of near-Earth objects, which have paths that take them within about 48 million kilometers (30 million miles) of Earth’s orbit.

"As WISE is orbiting the Earth, we are sweeping through the solar system like radar, and building up a map of what the solar system looks like in near infrared, looking for Near Earth Objects," said astronomer Tommy Grav of Johns Hopkins University.

Grav told Universe Today so far there haven't been any big surprises in the amount of NEOs the WISE team is finding. "We haven't done full analysis of all the data WISE has sent back, but we're finding about what we expected. We're right in the ballpark of what we expected to find."

The mission also studies the Trojans, asteroids that run along with Jupiter in its orbit around the sun in two packs — one in front of and one behind the gas giant. It has seen more than 800 of these objects, and by the end of the mission, should have observed about half of all 4,500 known Trojans. The results will address dueling theories about how the outer planets evolved.

"We can basically confirm and fill in the gap between ground based observations and the Spitzer Space Telescope's observations of the Trojan asteroids," Grav said.

Grav said WISE is an outstanding observatory. "We've basically done in six months what it took over 100 years to do in the optical."

Sources: NASA, AAS press conference


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NASA's WISE Eye on the Universe Begins All-Sky Survey Mission
LAUNCH OCCURRED ON 2009 DECEMBER 14 -  9:09:33 AM EST
 
The image “http://upload.wikimedia.org/wikipedia/commons/thumb/c/c3/WISE_Lifts_Off.jpg/399px-WISE_Lifts_Off.jpg” cannot be displayed, because it contains errors.
WISE has launched from Vandenberg Air Force Base, Calif. Image credit: United Launch Alliance
› Full resolution jpeg (3Mb)

VANDENBERG AIR FORCE BASE, Calif. -- NASA's Wide-field Infrared Survey Explorer, or WISE, lifted off over the Pacific Ocean this morning on its way to map the entire sky in infrared light.

A Delta II rocket carrying the spacecraft launched at 6:09 a.m. PST (9:09 a.m. EST 2009 Dec 14) from Vandenberg Air Force Base in California. The rocket deposited WISE into a polar orbit 326 miles above Earth.

http://www.redorbit.com/modules/imglib/download.php?Url=/modules/news/upload/1d0798035ac57a8894e2c0ec580d2e07.jpg

"WISE thundered overhead, lighting up the pre-dawn skies," said William Irace, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "All systems are looking good, and we are on our way to seeing the entire infrared sky better than ever before."

Engineers acquired a signal from the spacecraft via NASA's Tracking and Data Relay Satellite System just 10 seconds after the spacecraft separated from the rocket. Approximately three minutes later, WISE re-oriented itself with its solar panels facing the sun to generate its own power. The next major event occurred about 17 minutes later. Valves on the cryostat, a chamber of super-cold hydrogen ice that cools the WISE instrument, opened. Because the instrument sees the infrared, or heat, signatures of objects, it must be kept at chilly temperatures.
Its coldest detectors are less than minus 447 degrees Fahrenheit.

"WISE needs to be colder than the objects it's observing," said Ned Wright of UCLA, the mission's principal investigator. "Now we're ready to see the infrared glow from hundreds of thousands of asteroids, and hundreds of millions of stars and galaxies."

With the spacecraft stable, cold and communicating with mission controllers at JPL, a month-long checkout and calibration is underway.

WISE will see the infrared colors of the whole sky with sensitivity and resolution far better than the last infrared sky survey, performed 26 years ago. The space telescope will spend nine months scanning the sky once, then one-half the sky a second time. The primary mission will end when WISE's frozen hydrogen runs out, about 10 months after launch.

Just about everything in the universe glows in infrared, which means the mission will catalog a variety of astronomical targets. Near-Earth asteroids, stars, planet-forming disks and distant galaxies all will be easy for the mission to see. Hundreds of millions of objects will populate the WISE atlas, providing astronomers and other space missions, such as NASA's planned James Webb Space Telescope, with a long-lasting infrared roadmap.

JPL manages the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate in Washington. The mission was competitively selected under the Explorers Program, managed by NASA's Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp. in Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. NASA's Launch Services Program at NASA's Kennedy Space Center, Fla., managed the payload integration and the launch service.

More information about the WISE mission is available online at: http://www.nasa.gov/wise,   http://wise.astro.ucla.edu and  http://www.jpl.nasa.gov/wise.

 
 
Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

2009-193








WISE is shown here inside one-half of the nose cone, or fairing, that will protect it during launch


Other than the launch issues, everything is running fine. “Wise is chilled out. We've finished freezing the hydrogen that fills two tanks surrounding the science instrument. We're ready to explore the universe in infrared,” JPL Project Manager William Irace adds. He explains that, in order to be effective, WISE's instruments will be cooled almost to absolute zero. The coldest of these devices will operate at about eight degrees Kelvin, or minus 445 degrees Fahrenheit.

Other observatories, including NASA's Hubble and Spitzer Space Telescopes, the European Space Agency's (ESA) Herschel Space Observatory, and NASA's upcoming Sofia and James Webb Space Telescope, will follow up on WISE's finds. The new instrument will map the entire sky using four infrared wavelengths, the American space agency reports. “With infrared, we can find the dark asteroids other surveys have missed and learn about the whole population. Are they mostly big, small, fluffy or hard?” JPL Wise project scientist Peter Eisenhardt says.

“We should find several hundred brown dwarfs that are currently unknown. Many brown dwarfs are too cool to be detected with visible light. WISE will see most of them. It would be quite exciting to know how many brown dwarfs there are and how old they are,” Edward L. Wright, the principal investigator of the mission, shares. He is also the David Saxon Presidential Chair in Physics and a Professor of Physics and Astronomy at the University of California in Los Angeles (UCLA).

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PREVIOUS UPDATE TO THE ONE ABOVE:

PASADENA, Calif. -- The countdown clock is ticking, with just days to go before the Wide-field Infrared Survey Explorer, or WISE, rockets into space on a mission to map the entire sky in infrared light.

NASA's newest spacecraft is currently perched atop a United Launch Alliance Delta II rocket at Vandenberg Air Force Base, north of Santa Barbara, Calif. It is scheduled to roar into space at dawn on Dec. 11, at 6:09:33 a.m. PST (9:09:33 a.m. EST), on a short journey to its final Earth-circling orbit 525 kilometers (326 miles) overhead.

After a one-month checkout, the mission will spend the next nine months mapping the cosmos in infrared light. It will cover the whole sky one-and-a-half times, snapping millions of pictures of everything from near-Earth asteroids to faraway galaxies bursting with new stars.

"The last time we mapped the whole sky at these particular infrared wavelengths was 26 years ago," said Edward (Ned) Wright of UCLA, who is the principal investigator of the mission. "Infrared technology has come a long way since then. The old all-sky infrared pictures were like impressionist paintings -- now, we'll have images that look like actual photographs."

At liftoff, the main Delta II engine and three solid-motor boosters will ignite, providing a total liftoff thrust of more than 1,812,000 newtons (407,000 pounds). The rocket will tilt toward the south, cross the California coastline and head out over the Pacific Ocean. At one minute and 39 seconds after launch, the three spent boosters will fall away from the rocket. Two minutes and 45 seconds later, the main engine will cut off, and 14 seconds later, the vehicle's second stage will ignite. At four minutes and 56 seconds after liftoff, the "fairing" covering the satellite will split open like a clamshell and fall away.

The second stage of the rocket will then cut off, reigniting again 52 minutes after launch. It will shut down a second time and then, at about 55 minutes after launch, the spacecraft will reach its final orbit and separate from the rocket. Engineers expect to pick up a signal from WISE anywhere from about one to 10 minutes after separation.

The next major event will occur about 20 minutes after separation -- the valves on the spacecraft's cryostat will automatically open. The cryostat houses and chills the telescope and infrared detectors with tanks of frozen hydrogen. Valves on the cryostat are opened after launch to allow boiled-off hydrogen to escape, thereby preventing the instrument from warming up.

"It is important to relieve the pressure due to the warming hydrogen as soon as possible," said William Irace, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "By venting the hydrogen to space, we cool our instrument down to extremely low temperatures so that the eyes of WISE won't be blinded by their own heat."

After the spacecraft is checked out and calibrated, it will begin the task of surveying the whole sky. This will take about six months, after which the spacecraft will begin to sweep the sky a second time, covering about one-half before the frozen coolant runs out. The mission's primary lifetime is expected to be about 10 months.

The closest of the mission's finds will be asteroids and comets with orbits that come relatively close to Earth's path around the sun. These are called near-Earth objects. The infrared explorer will provide size and composition information about hundreds of these objects, giving us a better idea of their diversity. How many are dark like coal, and how many are shiny and bright? And how do their sizes differ? The mission will help answer these questions through its infrared observations, which provide information that can't be obtained using visible-light telescopes.

"We can help protect our Earth by learning more about the diversity of potentially hazardous asteroids and comets," said Amy Mainzer, deputy project scientist for the mission at JPL.

The farthest of the mission's targets are powerful galaxies that are either churning out loads of new stars or dominated by voracious black holes. These galaxies are shrouded in dust, and often can't be seen in visible light. WISE will expose millions, and may even find the most energetic, or luminous, galaxy in the universe.

"WISE can see these dusty objects so far away that we will be looking back in time 10 billion years, when galaxies were forming," said Peter Eisenhardt, the mission's project scientist at JPL. "By scanning the entire sky, we'll learn just how extreme this galaxy formation process can get."

JPL manages the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The mission's principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

More information is online at http://www.nasa.gov/wise, http://wise.astro.ucla.edu and http://www.jpl.nasa.gov/wise.

 
 
Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@jpl.nasa.gov

2009-188


Wide-Field Infrared Survey Explorer (WISE) is a NASA-funded scientific research project was launched at 9:09:33 AM  EST on December 14, 2009. The satellite will carry a 40 cm infrared-sensitive telescope and provide an "all-sky" survey in the 3 to 25 μm wavelength range (3.3, 4.7, 12, and 23 μm). The survey will be at least 500 times more sensitive than IRAS or Akari.

The spacecraft will be placed in a 525 km, circular, polar, synchronous orbit for its seven month mission, during which it will take 1.5 million 11-second exposure images, each covering a 47 arcminute field of view. The complete mission will include 99% of the sky with at least eight images from each position to increase accuracy.

The image library produced will contain data on the solar system, the Milky Way Galaxy, and the Universe. Among the objects WISE will study are cool, dim stars such as brown dwarfs, asteroids, and the most luminous infrared galaxies.

It has been approved by NASA to proceed to the construction stage. Construction is divided between Ball Aerospace & Technologies Corp.SSG Precision Optronics, Inc. (telescope, optics, scan mirror), DRS and Rockwell (focal planes), Lockheed Martin (cryostat, cooling for the telescope), and Space Dynamics Lab (instruments, electronics, and testing). The program is managed through the Jet Propulsion Laboratory. (spacecraft, operations support),

CONTENTS

  Spacecraft

The WISE spacecraft is built by Ball Aerospace and Technologies Corp. in Boulder, Colorado. The spacecraft is derived from the Ball Aerospace RS-300 spacecraft architecture, particularly the NEXTSat spacecraft built for the successful Orbital Express mission launched on March 9, 2007. The flight system has an estimated mass of 560 kg (about 1,175 pounds). The spacecraft will be three-axis stabilized, with body-fixed solar arrays and use a high-gain antenna in the Ku-band to transmit to ground through the TDRSS geostationary system. In addition to building the spacecraft, Ball Aerospace will perform test and flight system integration.

  Science mission

WISE will survey the sky in four wavelengths of the infrared band at a very high sensitivity. Its detector arrays have sensitivity limits of 120, 160, 650, and 2600 µJy at 3.3, 4.7, 12, and 23 microns.[2] This is a factor of a thousand times better sensitivity than the survey completed in 1983 by the IRAS satellite in the 12 and 23 micron bands, and a factor of five hundred thousand times better than the 1990s survey by the COBE satellite at 3.3 and 4.7 microns.[2]

  • Band 1 - 3.4 microns—broad-band sensitivity to stars and galaxies
  • Band 2 - 4.6 microns—detect thermal radiation from the internal heat sources of sub-stellar objects like brown dwarfs
  • Band 3 - 12 microns—detect thermal radiation from asteroids
  • Band 4 - 22 microns—sensitivity to dust in star-forming regions (material with temperatures of 70-100 Kelvin)

On November 8, 2007, the House Committee on Science and Technology's Subcommittee on Space and Aeronautics held a hearing to examine the status of NASA's Near-Earth Object (NEO) survey program. The prospect of using WISE was proposed by NASA officials.[3] NASA officials told Committee staff that NASA plans to use WISE to detect NEOs, in addition to performing its science goals. It is projected that WISE could detect 400 NEOs [or roughly 2 percent of the estimated NEO population of interest] within the 1 year mission.

WISE will not be able to detect Kuiper belt objects, as their temperature is too low.[4] It will be able to detect any objects with an internal heat source: a Neptune-sized object would be detectable out to 700 AU, a Jupiter-mass object out to one lightyear (63,000 AU), where it would still be within the Sun's zone of gravitational control.[4] A small brown dwarf of 2-3 Jupiter masses would be visible at a distance of up to two to three parsecs.[4]

  Project milestones

The WISE Mission is led by Dr. Edward L. Wright of the University of California, Los Angeles. The mission has a long history under Dr. Wright's efforts, and was first funded by NASA in 1999 as a candidate for a NASA Medium-class Explorer (MIDEX) mission under the name Next Generation Sky Survey (NGSS). The history of the program from 1999 to date is briefly summarized as follows:

  • January 1999 - NGSS is one of five missions selected for a Phase A study, with an expected selection in late 1999 of two of these five missions for construction and launch, one in 2003 and another in 2004. Mission cost is estimated at $139 million at this time.
  • October 1999 - Winners of MIDEX study are awarded, and NGSS is not selected.
  • October 2001 - NGSS proposal is re-submitted to NASA as a MIDEX mission.
  • April 2002 - NGSS proposal is accepted by the NASA Explorer office to proceed as one of 4 MIDEX programs for a Pre-Phase A study.
  • December 2002 - NGSS changes its name to Wide-field Infrared Survey Explorer (WISE).
  • March 2003 - NASA releases a press release announcing WISE has been selected for an Extended Phase-A study, leading to a decision in 2004 on whether to proceed with the development of the mission.
  • April 2003 - Ball Aerospace is selected as the spacecraft provider for the WISE mission.
  • April 2004 - WISE is selected as NASA's next MIDEX mission. WISE's cost is estimated at $208 million at this time.
  • November 2004 - NASA selects the Space Dynamics Laboratory at Utah State University to build the telescope for WISE.
  • October 2006 - WISE is confirmed for development by NASA and authorized to proceed with development. Mission cost at this time is estimated to be $300 million.

  References

  1. ^ "Shuttle and Rocket Launch Schedule". NASA. August 29, 2009. http://www.nasa.gov/missions/highlights/schedule.html. Retrieved 2009-09-04. 
  2. ^ a b Mainzer, Amanda K.; Eisenhardt, Peter; Wright, Edward L.; Liu, Feng-Chuan; Irace, William; Heinrichsen, Ingolf; Cutri, Roc; Duval, Valerie (2005). MacEwen, Howard A.. ed. Preliminary design of the Wide-Field Infrared Survey Explorer (WISE). Proceedings of the SPIE. UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts II. Vol. 5899. pp. 262-273. http://wise.ssl.berkeley.edu/documents/WISESPIE_SanDiego05.pdf. 
  3. ^ Hearing Charter: Near-Earth Objects: Status of the Survey Program and Review of NASA's 2007 Report to Congress. Committee on Science and Technology, U.S. House of Representatives. 7 November 2007. http://www.spaceref.ca/news/viewsr.html?pid=25960. Retrieved 2009-03-06. 
  4. ^ a b c Emily Lakdawalla (27 August 2009). "The Planetary Society Blog: "WISE Guys"". The Planetary Society. http://www.planetary.org/blog/article/00002070/. Retrieved 2009-08-27. 

  External links

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