August 22, 2012
Scientists To Study Earth’s Radiation Belt With High-Tech Satellite Instruments
Lawrence LeBlond for redOrbit.com - Your Universe Online
NASA is launching twin satellites on August 24 from Cape Canaveral, Florida that will conduct the most intimate study to date of the Van Allen Radiation Belts that envelop Earth. The two-year Radiation Belt Storm Probes (RBSP) mission will study the extremes of space weather and should help scientists improve space weather forecasting.
Space weather doesn´t seem like a big deal to most people on Earth, but, according to one researcher from University of Iowa, everybody is affected by it. Pick up your cell phone to make a call; take a flight on your next vacation; step outside to catch a glimpse of the northern lights; these are all instances where you become affected by space weather. And changes in space weather can wreak havoc on satellites, power grids, and GPS systems.
The Van Allen Radiation Belts, named after UI astrophysicist James A. Van Allen who discovered the phenomena in 1958 during the flight of the Explorer 1 satellite, are two donut-shaped regions of high-energy particles trapped by the Earth´s magnetic field. When first discovered, the belts were thought to remain fairly stable. However, future observations revealed that these structures are not nearly as stable as believed. And even now, the reasons why are a mystery.
The twin satellites are scheduled for a 4:07 a.m. (EST) lift-off on August 24 aboard a United Launch Vehicle Atlas V rocket from Cape Canaveral. A host of highly-sensitive instruments equipped to the satellites will aid in the study of the radiation belts.
Harlan Spence, director of the University of New Hampshire (UNH) Institute for the Study of Earth, Oceans, and Space, is leading the studies involving the Energetic Particle, Composition, and Thermal Plasma (ECT) instrument. Roy Torbert, director of UNH℠s Space Science Center (SSC), is a co-leader on the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) experiment. The principal investigator for the EMFISIS instrument is Craig Kletzing, F. Wendell Miller Professor of physics and astronomy in the University of Iowa College of Liberal Arts and Sciences.
Teams from the University of Minnesota, the New Jersey Institute of Technology, and the National Reconnaissance Office will operate three other instruments aboard the twin satellites, each of which weighs 1,455 pounds and were built for NASA at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland.
Collectively, the five instrument suites will give scientists the most precise measurements to date of the high-energy particles and magnetic and electric fields and waves in this near-Earth region of space where space weather occurs.
Space weather is largely affected by activity from the Sun, including solar storms (coronal mass ejections) which can be massive and pose serious threats to electrical systems in our orbit and here on the surface of the planet. The RSBP mission will enable a better understanding of space weather conditions and allow scientists to better predict the severity of such events, events that can not only disrupt electrical systems, but also pose a danger to human health.
“There can be a solar storm and the radiation belts will get pumped up, or nothing happens, or they'll nearly disappear entirely. That's puzzling, and right now we don't understand enough to say why it's the case,” said Spence at a pre-launch press conference held on August 20.
To gain a better understanding of the radiation belts and how it affects space weather, the dual satellites will chase each other in common, highly-elliptical orbits to achieve simultaneous spatial and temporal measurements of the particles and the magnetic and electrical fields and waves.
“We know we can't study the particles in the absence of the electromagnetic fields that are causing them to change,” noted Spence. “Until RBSP there has never been a comprehensive, coordinated investigation with two spacecraft simultaneously.”
Spence´s ECT suite is comprised of three main instruments including the Magnetic Electron Ion Spectrometer, which has four versions on each satellite. Other instruments in the ECT suite include the Helium Oxygen Proton Electron spectrometer and the Relativistic Electron Proton Telescope. The ECT suite was developed with the aid of several organizations including the Los Alamos National Laboratory, Southwest Research Institute (SWRI), The Aerospace Corporation, and the University of Colorado.
Besides developing partners, the ECT suite also has a host of partners, including teams from Dartmouth College, UCLA, NASA Goddard Space Flight Center, and NOAA Space Weather Prediction Center, as well as international partners at the University of Alberta, the British Antarctic Survey, and the Office National d'Ãtudes et de Recherches Aerospatiales (ONERA) in Toulouse, France.
“The EMFISIS suite will measure the electric and magnetic fields and waves that both result from radiation belt particle interactions and have a significant effect on both the energization and loss of these particles. Having two satellites in the same orbit gives us new insights into these processes and how they change in time and space,” said Torbert at a pre-launch press conference.
The RSBP mission is the first such mission to be launched by NASA in more than two decades. Like other NASA projects, this mission has two main reasons for existing: it will gather practical information and it is a part of mankind´s continuing exploration of space.
“The practical reason is: that's a part of space that we utilize. The outer radiation belts are where all our communication satellites exist, the various things that make sure that GPS works, as well as telephone communications,” Kletzing said. “They can be affected by these particles, and, in fact, it has happened that those satellites have actually been knocked out by radiation.”
“So, understanding these effects and how they happen and, hopefully, get beyond to where we can do some level of prediction is a very important practical reason,” he added.
“Additionally, the various manned missions that NASA has planned to go beyond the Space Station to places like the moon or Mars also require transiting through this region,” noted Kletzing. “So, understanding the right time to go–when the particles are fewest so that you don't impact human health–is a very important thing to understand.”
The most exciting part of this project is that this is the first time NASA is launching twin satellites; two identical satellites, each carrying the same sets of instrumentation, that will offer scientists for the first time to get comparable evidence from two sources instead of relying on just one, according to Kletzing.
The UI´s EMFISIS instruments will measure the various kinds of waves the spacecraft will encounter. UI´s Kletzing and co-investigator Bill Kurth, also of UI, built the Waves and search coil magnetometer sections for the EMFISIS suite. The UI also worked with the Goddard Space Flight Center, which built a magnetometer as a part of the UI instrument suite. UNH provided the computer that controls all of the EMFISIS measurements.
The RBSP mission is part of NASA´s Living With a Star program, an effort to learn more about the sun-Earth interaction, which is managed by Goddard Space Flight Center.