Posts tagged NASA
$6 million CU-Boulder instrument to fly on Sept. 6 NASA mission to moon
Aug 29th
A $6 million University of Colorado Boulder instrument designed to study the behavior of lunar dust will be riding on a NASA mission to the moon now slated for launch on Friday, Sept. 6, from the agency’s Wallops Flight Facility in Virginia.
The mission, known as the Lunar Atmosphere and Dust Environment Explorer, or LADEE, will orbit the moon to better understand its tenuous atmosphere and whether dust particles are being lofted high off its surface. The $280 million LADEE mission, designed, developed, integrated and tested at NASA’s AMES Research Center in Moffett Field, Calif., will take about a month to reach the moon and another month to enter the proper elliptical orbit and to commission the instruments. A 100-day science effort will follow.
“We are ready and excited for launch,” said CU-Boulder physics Professor Mihaly Horanyi of the Laboratory for Atmospheric and Space Physics, principal investigator for the Lunar Dust Experiment, or LDEX. “We think our instrument can help answer some important questions related to the presence and transport of dust in the lunar atmosphere.”
One unanswered question since the days of the Apollo program is why astronauts saw a pre-sunrise glow above the lunar horizon, said Horanyi, who directs LASP’s Colorado Center for Lunar Dust and Atmospheric Studies. “The glow has been suggested to be caused by dust particles that were electrically charged by solar ultraviolet light, causing them to lift off from the moon’s surface.”
About the size of a small toaster oven, the LDEX instrument will be able to chart the existence, size and individual velocities of tiny dust particles as small as 0.6 microns in diameter. For comparison, a standard sheet of paper is about 100 microns thick. A collision between a dust particle and a hemisphere-shaped target on LDEX generates a unique electrical signal inside the instrument to allow scientists to detect individual particles, said Horanyi.
Horanyi said clouds of dust specks seemingly observed by astronauts hovering over the moon likely weren’t clouds at all. “If you watch a cement truck on the highway, it seems to be carrying a dust cloud along with it. But what is actually happening is that every speck of dirt coming off the truck is falling onto the highway,” he said.
“The specks have very short lifespans, and the cloud that appears to surround the truck is actually a continual rain of dust from the vehicle to the pavement,” he said. “Similarly, the smallest lunar dust particles could also continually lift off and fall back onto the surface.”
Knowing more about the behavior of lunar dust could be of use for future human expeditions to the moon, including potential colonization efforts. Learning more about lunar dust also might help scientists better understand dust on other moons in the solar system — like Phobos and Deimos that orbit Mars – that have been suggested by some as possible initial landing posts for crewed missions headed to the Red Planet.
LADEE also is carrying an ultraviolet and visible light spectrometer, a neutral mass spectrometer and a lunar laser communications demonstration.
Astronauts walking on the moon sank into a shallow layer of dust, thought to be a product of millions of years of meteoric and interstellar particle bombardment, he said. “The beauty of physics is that we believe the same processes occur throughout the universe,” he said. “What we see on the moon may well apply to Mercury, Phobos, Deimos or asteroids, which all have very tenuous atmospheres.”
When the LADEE spacecraft is inserted into an elliptical orbit, its closest approach will be less than 20 miles from the lunar surface. “The closer we can get to the surface the better,” he said.
“This is a very exciting mission that will answer an almost 50-year-old question in space science,” said CU-Boulder graduate student Jamey Szalay, who is writing data analysis software for the mission that will allow the team to analyze science results immediately after data is received from the spacecraft. “Given the convenient duration of the mission and promising science return, I’m very fortunate to be a part of the science team — it’s a dream project for any graduate student in space sciences to be working on.”
Horanyi also is the principal investigator on CU-Boulder’s Student Dust Counter, a simpler instrument than LDEX flying on NASA’s New Horizons mission that was launched in 2006 to explore Pluto and the Kuiper Belt, a massive region beyond the planets containing icy objects left over from the formation of the solar system. The Student Dust Counter was designed, built, tested and operated entirely by students, primarily undergraduates, at LASP and has been collecting data for the past seven years. New Horizons is now more than 2.5 billion miles from Earth and will arrive at Pluto in two years.
CU-Boulder researcher David James, who now is working on LDEX, got his start helping to build SDC. “Although I was a student in a lab back then, it was almost like working in the private sector,” said James, who eventually received his doctorate from CU-Boulder. “We were building an instrument that was going to Pluto. It was an amazing experience with huge responsibilities, it pushed us to do our best, and it definitely shaped who I am today.”
The LDEX instrument, as well as many previous LASP instruments launched into space since the 1970s, will carry a laser engraving of the CU mascot, Ralphie the Buffalo, as well as the names of all university people who participated in the project, from students and scientists to engineers and administrative support staff. “It’s like adding a touch of history to the mission, perhaps for good luck and pride,” said Horanyi. “After all, this is the University of Colorado.”
-CU-
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NASA-CU Boulder mission discovers particle accelerator in heart of Van Allen radiation
Jul 26th
The new results from NASA’s Van Allen Probes mission show the acceleration energy is in the belts themselves. Local bumps of energy kick particles inside the belts to ever-faster speeds, much like a well-timed push on a moving swing. Knowing the location of the acceleration within the radiation belts will help scientists improve predictions of space weather, which can be hazardous to satellites near Earth. The results were published July 25 in the journal Science.
“Until the 1990s, we thought the Van Allen belts were pretty well-behaved and changed slowly,” says Geoff Reeves, lead author on the paper and a radiation belt scientist at Los Alamos National Laboratory in Los Alamos, N.M. “With more and more measurements, however, we realized how quickly and unpredictably the radiation belts change. They are basically never in equilibrium, but in a constant state of change.”
In order for scientists to understand such changes better, the twin Van Allen Probes fly straight through this intense area of space. One of the top priorities for the mission, launched last August, is to understand how particles in the belts are accelerated to ultra-high energies.
“We see case after case where the very high energy electrons appear suddenly right in the heart of the outer belt,” said CU-Boulder Professor Daniel Baker, director of the Laboratory for Atmospheric and Space Physics and a study co-author. “But now we can prove where the electrons originate from and we can see the waves — and the lower energy ‘seed’ particles — from which the relativistic electrons grow. We can essentially peer into the inner workings of our local cosmic accelerator with unprecedented clarity.”
By taking simultaneous measurements with advanced technology instruments, the Van Allen Probes were able to distinguish between two broad possibilities on what accelerates the particles to such amazing speeds. The possibilities are radial acceleration or local acceleration. In radial acceleration, particles are transported perpendicular to the magnetic fields that surround Earth, from areas of low magnetic strength far from Earth to areas of high magnetic strength closer to Earth.
Physics dictates particle speeds in this scenario will increase as the magnetic field strength increases. The speed of the particles would increase as they move toward Earth, much the way a rock rolling down a hill gathers speed due to gravity. The local acceleration theory proposes the particles gain energy from a local energy source, similar to the way warm ocean water can fuel a hurricane above it.
Reeves and his team found they could distinguish between these two theories when they observed a rapid energy increase in the radiation belts Oct. 9, 2012. The observations did not show an intensification in particle energy starting at high altitude and moving gradually toward Earth, as would be expected in a radial acceleration scenario. Instead, the data showed an increase in energy that started right in the middle of the radiation belts and gradually spread both inward and outward, implying a local acceleration source. The research shows this local energy comes from electromagnetic waves coursing through the belts, tapping energy from other particles residing in the same region of space.
“These new results go a long way toward answering the questions of where and how particles are accelerated to high energy,” said Mona Kessel, Van Allen Probes program scientist in Washington. “One mission goal has been substantially addressed.”
The challenge for scientists now is to determine which waves are at work, according to the science team. The Van Allen Probes, which are designed to measure and distinguish between many types of electromagnetic waves, will tackle this task, too.
Baker said the new findings would not have been possible without the Relativistic Electric Proton Telescope, or REPT, developed by a team at CU-Boulder’s LASP and which is riding on the Van Allen Probes. CU-Boulder will receive more than $18 million from NASA over the Van Allen Probes mission lifetime for REPT and an electronics package known as the Digital Fields Board, said Baker, who led the LASP team that developed REPT.
“I think we are now getting a crash course in true radiation belt physics,” said Baker. “While before we were nibbling at the edges or looking through a cloudy screen, things are incredibly clear now. With our beautiful new sensors, we can see almost every ‘thumbprint’ of every large solar storm that has impressed itself on the Earth’s radiation belts.”
The Johns Hopkins University Applied Physics Laboratory in Laurel, Md., built and operates the twin Van Allen Probes for NASA’s Science Mission Directorate. The Van Allen Probes are the second mission in NASA’s Living With a Star program, managed by NASA’s Goddard Space Flight Center in Greenbelt, Md. The program explores aspects of the connected sun-Earth system that directly affect life and society.
For more information about the Van Allen Probes visit:
http://www.nasa.gov/vanallenprobes. For more information on LASP visit http://lasp.colorado.edu/home/.
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CU-Boulder study: Spiral galaxies like Milky Way bigger than thought
Jun 27th
CU-Boulder Professor John Stocke, study leader, said new observations with Hubble’s $70 million Cosmic Origins Spectrograph, or COS, designed by CU-Boulder show that normal spiral galaxies are surrounded by halos of gas that can extend to over 1 million light-years in diameter. The current estimated diameter of the Milky Way, for example, is about 100,000 light-years. One light-year is roughly 6 trillion miles.
The material for galaxy halos detected by the CU-Boulder team originally was ejected from galaxies by exploding stars known as supernovae, a product of the star formation process, said Stocke of CU-Boulder’s astrophysical and planetary sciences department. “This gas is stored and then recycled through an extended galaxy halo, falling back onto the galaxies to reinvigorate a new generation of star formation,” he said. “In many ways this is the ‘missing link’ in galaxy evolution that we need to understand in detail in order to have a complete picture of the process.”
Stocke gave a presentation on the research June 27 at the University of Edinburgh’s Higgs Centre for Theoretical Physics in Scotland at a conference titled “Intergalactic Interactions.” The CU-Boulder research team also included professors Michael Shull and James Green and research associates Brian Keeney, Charles Danforth, David Syphers and Cynthia Froning, as well as University of Wisconsin-Madison Professor Blair Savage.
Building on earlier studies identifying oxygen-rich gas clouds around spiral galaxies by scientists at the Space Telescope Science Institute in Baltimore, the University of Massachusetts, Amherst College and the University of California, Santa Cruz, Stocke and his colleagues determined that such clouds contain almost as much mass as all the stars in their respective galaxies. “This was a big surprise,” said Stocke. “The new findings have significant consequences for how spiral galaxies change over time.”
In addition, the CU-Boulder team discovered giant reservoirs of gas estimated to be millions of degrees Fahrenheit that were enshrouding the spiral galaxies and halos under study. The halos of the spiral galaxies were relatively cool by comparison — just tens of thousands of degrees — said Stocke, also a member of CU-Boulder’s Center for Astrophysics and Space Astronomy, or CASA.
Shull, a professor in CU-Boulder’s astrophysical and planetary sciences department and a member of CASA, emphasized that the study of such “circumgalactic” gas is in its infancy. “But given the expected lifetime of COS on Hubble, perhaps another five years, it should be possible to confirm these early detections, elaborate on the results and scan other spiral galaxies in the universe,” he said.
Prior to the installation of COS on Hubble during NASA’s final servicing mission in May 2009, theoretical studies showed that spiral galaxies should possess about five times more gas than was being detected by astronomers. The new observations with the extremely sensitive COS are now much more in line with the theories, said Stocke.
The CU-Boulder team used distant quasars — the swirling centers of supermassive black holes — as “flashlights” to track ultraviolet light as it passed through the extended gas haloes of foreground galaxies, said Stocke. The light absorbed by the gas was broken down by the spectrograph, much like a prism does, into characteristic color “fingerprints” that revealed temperatures, densities, velocities, distances and chemical compositions of the gas clouds.
“This gas is way too diffuse to allow its detection by direct imaging, so spectroscopy is the way to go,” said Stocke. CU-Boulder’s Green led the design team for COS, which was built by Ball Aerospace & Technologies Corp. of Boulder for NASA.
While astronomers hope the Hubble Space Telescope keeps on chugging for years to come, there will be no more servicing missions. And the James Webb Space Telescope, touted to be Hubble’s successor beginning in late 2018, has no UV light-gathering capabilities, which will prevent astronomers from undertaking studies like those done with COS, said Green.
“Once Hubble ceases to function, we will lose the capability to study galaxy halos for perhaps a full generation of astronomers,” said Stocke. “But for now, we are fortunate to have both Hubble and its Cosmic Origins Spectrograph to help us answer some of the most pressing issues in cosmology.”
The study was supported by a NASA/Hubble Space Telescope contract to the Cosmic Origins Spectrograph science team, general NASA/Hubble Space Telescope observing grants to Stocke and a National Science Foundation grant to Keeney.
-CU-
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