Van Allen Probe, Photo credit: JHU-APL
Now deep into the scientific discovery phase of a two-year orbit, NASA’s Van Allen Probes, carrying an NJIT instrument that measures the composition of the radiation belts surrounding Earth, are shedding new light on a hazardous, little-understood region of the planet’s outermost atmosphere. The probes have revealed, for example, hitherto undetected zones of high-energy helium ions within the belts, as well as the surprising discovery of bands of electrons arranged in patterns that resemble zebra stripes.
Late last month, NJIT and its partners received word from NASA that the Van Allen Probes, carrying NJIT’s Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE), had met all of the scientific criteria to be designated a “Mission Success.”
None of its discoveries would have been possible, however, if the suite of instruments hurtling around the Earth at an average speed of 2000 mph aboard twin spacecraft had failed to function properly following the 2012 launch. Operational success, space researchers say, is no small achievement. The radiation belts, composed of layers of charged particles held in place by Earth’s magnetic field, are one of the most dangerous zones in Earth’s upper atmosphere and most spacecraft avoid them for a reason.
So it was with considerable satisfaction – not to mention relief – that the NJIT-led RBSPICE team also received a Group Achievement Award by NASA citing the mission’s outstanding cost and schedule performance, as well as its groundbreaking science. The certificate recognizes group accomplishment that “contributes substantially to NASA's mission."
At a ceremony last year at NASA headquarters in Washington, D.C. the space agency’s administrator, Gen. Charles Bolden, Jr. congratulated the team for setting a bar by which all other NASA missions are measured. More recently, NJIT team members, along with partners from the Applied Physics Laboratory at Johns Hopkins University and Fundamental Technologies, LLC, received individual certificates for their roles in conceiving, designing, and building the instrument.
“The mission has been highly successful both in the operations of the spacecraft and in the operations of the instruments,” notes Louis Lanzerotti, distinguished research professor of physics at NJIT’s Center for Solar-Terrestrial Research and the principal investigator of the mission. “Almost anything you can imagine can go wrong with a space mission. The most serious, of course, is a launch failure, and then an instrument failure.”
NJIT’s instruments are measuring protons, helium ions and oxygen ions at the mid-level range of the energy spectrum in the radiation belts, which are between 6,000 miles to 25,000 miles above the Earth’s surface. Awarded just over $15 million by NASA to complete its work next year, NJIT and its partners are hoping to extend the mission for another two and a half years if NASA agrees to fund it.
“This is NJIT’s first spacecraft-based mission and we are ecstatic with the world-class instrument the team designed, which is producing cutting-edge science and advancing our understanding of the radiation belts,” says Andrew Gerrard, deputy director of NJIT’s Center for Solar Terrestrial Research and RBSPICE science team member. “We have not had this level of coverage of the radiation belts since the 1980s, and a mission extension would uniquely allow us to contribute to upcoming space missions.”
The NJIT team wrote the RBSPICE proposal in 2005 and the mission was selected the next year for flight along with four other teams, including other universities and the National Reconnaissance Office.
“Competition is usually very keen for flight opportunities,” Lanzerotti says.
At the time of the launch, he described the mission as a “major step forward in quantifying and eventually predicting conditions in space around Earth” that he hoped would lead to discoveries about the mechanics and processes that alter the size and intensity of the radiation belts.
The mission is part of NASA’s Living With A Star program, managed by Goddard Space Flight Center, and is tasked with investigating changes in the sun’s energy flow – and especially its extreme conditions – which can disable satellites, cause power grid failures and disrupt GPS services on Earth, and harm spacecraft in orbit.
“The different instrument teams, including ours, have discovered new insights about the radiation belts that we did not know prior to the mission. Results are still coming in as well,” Lanzerotti observed recently.
Commenting on scientific advances since the early days of radiation belt research in the 1960s when he was a young scientist at Bell Labs, he added, “The first mission where I actually helped build and test the instrument was for the first NASA geosynchronous satellite named ATS-1 (in the mid-1960s). The radiation environment at geosynchronous altitude – its changes in time and space around Earth where most communication spacecraft now fly – was totally unknown at the time.”
Lanzerotti recently co-authored a paper published in the journal Nature that demonstrated that highly energized populations of electrons in the inner radiation belt are organized into structured patterns that resemble slanted zebra stripes. Scientists had previously believed that increased solar wind activity was the primary force behind any structures in Earth’s radiation belts, but data gathered on the mission led to the surprising discovery that the stripes are induced by Earth’s electric fields.
Gerrard’s recent paper, in the special issue of Geophysical Research Letters on early discoveries from the Van Allen Probes mission, highlights an unexplored population of helium ions that appear to be sensitive tracers of ring current dynamics, a system around Earth that helps form the radiation belts. The new helium population can, for example, be used to explore the impacts of Earth's electric field variability on particle loss.