Posts tagged LASP
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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NASA sends CU Boulder big bucks for space weather mission
Apr 15th
The University of Colorado Boulder will receive roughly $36 million from NASA to build and operate a space instrument for a mission led by the University of Central Florida that will study Earth’s upper atmosphere to learn more about the disruptive effects of space weather.
The mission, known as the Global-scale Observations of the Limb and Disk, or GOLD, involves imaging Earth’s upper atmosphere from a geostationary orbit some 22,000 miles above the planet. The mission is expected to have a direct impact on the understanding of space weather like geomagnetic storms that alter the temperature and composition of Earth’s atmosphere, which can disrupt communication and navigation satellites, affecting everything from automobile GPS and cell phone coverage to television programming.
The GOLD mission, which is being led by research scientist Richard Eastes of the University of Central Florida, will launch aboard a commercial communications satellite as a “hosted” payload. Such payloads, which are secondary to the satellite’s main objective, represent the most cost-effective way to reach geostationary orbit, said CU-Boulder aerospace engineer Mark Lankton of the Laboratory for Atmospheric and Space Physics, the GOLD project manager.
“LASP is extremely pleased to be working on this mission with Richard Eastes at the University of Central Florida, who we have been collaborating with for seven years,” said Lankton. “This mission is one of the first to involve a science instrument being launched on a communication satellite, which is a terrific idea and exactly the right way to run a quality mission on a smaller budget.”
The LASP instrument, known as an imaging spectrograph, weighs roughly 60 pounds and is about 2 feet long and about 1 foot tall and 1 foot wide – roughly the size of a microwave oven. It will launch aboard a commercial satellite built by SES Government Solutions in McLean, Va. The LASP instrument will be gathering data on Earth’s upper atmosphere in the far ultraviolet portion of the electromagnetic spectrum.
“GOLD’s imaging represents a new paradigm for observing the boundary between Earth and space,” said Bill McClintock, the deputy principal investigator on the CU-Boulder spectrograph and a senior research scientist at LASP. “It will revolutionize our understanding of how the sun and the space environment affect our upper atmosphere.”
A geosynchronous orbit is an orbit that completes one revolution in the same amount of time it takes for the Earth to rotate once on its polar axis. “We will be able to view almost a complete hemisphere of the Earth, almost all the time, with this orbit,” said Lankton.
The mission scientists will be looking for the effects of space weather on the upper atmosphere — the ionosphere and thermosphere located roughly 50 miles to 350 miles above Earth – caused by the sun and Earth’s lower atmosphere, said Lankton. “The giant driver is the sun, including geomagnetic storms that can cause bright auroras and the disruption of satellite communications,” he said.
Lankton said the science team also will investigate the effects that atmospheric waves and tides from Earth’s lower atmosphere have on the thermosphere-ionosphere system. The mission will make use of other instruments gathering data on the sun, including LASP’s $42 million Extreme Ultraviolet Variability Experiment flying on NASA’s Solar Dynamics Observatory.
Roughly 40 LASP researchers will be working on the GOLD mission when it is at full strength, including five to 10 students, split about evenly between undergraduates and graduates, said Lankton. Other participants in the GOLD mission include the National Center for Atmospheric Research in Boulder, the University of California, Berkeley, Computational Physics Inc. of Springfield, Va., and the National Oceanic and Atmospheric Administration.
The GOLD mission is part of NASA’s new Heliospheric Explorer Program designed to provide space observations to study Earth’s ionosphere and thermosphere. The mission is slated for launch in 2017. NASA Explorer missions of opportunity, such as GOLD, are capped at $55 million each.
by CU media relations
CU Boulder’s sun-gazing SORCE satellite, designed to last 5 years, turns 10
Jan 22nd
A decade later, the four instruments onboard the Solar Radiation and Climate Experiment, or SORCE, have given scientists an unprecedented look at some of the most intense solar eruptions ever witnessed — including the notorious Halloween storms in October and November 2003 — as well as the anomalously quiet solar minimum that hushed the sun’s surface beginning in 2008 and, now, a new solar maximum that appears to be the least active in a century.
“We were there to see it transform from a fairly normal solar cycle to a very low-activity solar cycle,” said Tom Woods, associate director of CU-Boulder’s Laboratory for Atmospheric and Space Physics, known as LASP, and principal investigator for SORCE. “Of course we couldn’t predict or know that, but it’s very exciting.”
The data generated by SORCE’s instruments, which were originally designed to operate for just five years, are downloaded twice a day with the help of CU-Boulder undergraduates working at LASP mission control. Scientists are now using that data to better understand how energy from the sun affects Earth’s climate. While human-produced greenhouse gases have been the dominant driver of climate change over the last several decades, the activity of the sun can either enhance or offset the resulting global warming.
“About 10 to 15 percent of the climate warming since 1970 is due to the sun,” Woods said. “That’s going to change now. Now that solar activity is low, the global warming trend could slow down some, but not nearly enough to offset the anthropogenic effects on global warming.”
The current, lackluster solar maximum is being compared to periods when astronomers observed very few sunspots in the early 19th century known as the Dalton Minimum and in the last half of the 17th century known as the Maunder Minimum. During the Maunder Minimum, which coincided with an era known as the Little Ice Age, temperatures in Europe were especially cool, with rivers and canals freezing during the winter across the continent and rapidly advancing glaciers destroying villages in the Swiss Alps.
The SORCE mission is also a critical contributor to the long-term record of total solar irradiance — the magnitude of the sun’s energy when it reaches the top of the Earth’s atmosphere — which stretches back to 1978, when the Nimbus-7 satellite was launched. The Total Irradiance Monitor, or TIM, instrument onboard SORCE is taking the most accurate and most precise measurements of total solar irradiance ever collected.
“The total solar irradiance provides nearly all the energy powering the Earth’s climate system, exceeding all other energy sources combined by 2,500 times,” said Greg Kopp, LASP senior research scientist and co-investigator responsible for the TIM instrument. “Any change in total irradiance can thus have large effects on our climate.”
Data from the SORCE mission have also begun a new record for measurements of visible and near-infrared light emitted from the sun. The solar spectral irradiance measurements are being made for the first time by the Spectral Irradiance Monitor, or SIM. Combined with other instruments onboard SORCE, scientists can now see all the wavelengths, including those in the ultraviolet range, emitted by the sun at once. This new way of seeing the sun has led to interesting discoveries, including that the energy emitted in some wavelengths of light vary out of phase with the sun’s overall activity, actually increasing as the number of sunspots decreases.
Now that SORCE has doubled its original life expectancy, LASP scientists are building new instruments to take over when SORCE gives out. A new TIM built at LASP launched on NASA’s Glory mission in 2011, but the satellite failed to make orbit. After the loss of Glory, CU-Boulder scientists, determined to avoid a gap in the record of total solar irradiance measurements, came up with a creative solution, repurposing a ground-based TIM to quickly make it space-worthy and then integrating it onto a U.S. Air Force satellite built by Ball Aerospace that is set to launch in August of this year.
“It’s important to have continuous measurements of solar irradiance since we’re looking for small changes in the sun’s output over decades and even centuries,” said Kopp. “Detecting such small changes using measurements disconnected in time would make this even more difficult.”
A new SIM instrument, also built at LASP, is scheduled to launch in 2016 on a National Oceanic and Atmospheric Administration satellite. But while SORCE is expected to continue functioning for at least another year, allowing for overlapping measurements with the TIM instrument launching in August, it’s uncertain if SORCE’s SIM instrument will still be running when its successor makes it to space in 2016.
“We’re definitely hoping and planning that SORCE lasts through this year,” Woods said. “But 2016 — I don’t think SORCE’s battery is going to last that long.”
During SORCE’s 10-year foray in space, the satellite also witnessed two rare transits of the planet Venus in front of the sun and another two less-infrequent transits by Mercury. When Venus, the larger of the two planets and the closer to Earth, blocked out part of the sun’s light, SORCE’s TIM instrument measured a corresponding drop in the amount of total solar irradiance. The measurements are now useful reference tools for astronomers hoping to discover planets around other stars by measuring a dip in a star’s light from a planetary transit.
In all, CU-Boulder has received about $120 million from NASA for the construction and operation of SORCE. But in 2008, LASP took the unusual step of returning $3 million in cost savings from the SORCE mission to NASA that resulted from the program’s efficient operations.
Researchers at LASP are planning to celebrate SORCE’s 10th birthday with cake, a science seminar and a write-up of the satellite’s top-10 accomplishments in NASA’s The Earth Observer magazine.
But while the decade mark is typically an important milestone for celebration here on Earth, the more appropriate milestone for SORCE may come in 2014 at the 11-year mark, the average length of a complete solar cycle
“Eleven years is special to us,” Woods said. “Instead of having a big science conference this year, we’re planning it for next January.”
For more information, visit LASP’s SORCE website at http://lasp.colorado.edu/sorce/index.htm.
A video of CU-Boulder researchers discussing the SORCE mission is available at http://www.colorado.edu/news/multimedia/cu-boulders-sun-gazing-satellite-turns-10-0.