Edwin L. Aguirre
It’s like having a dead person start talking again after 12 years.
That is how physics
Prof. Paul Song
, a NASA satellite launched in 2000 that operated for nearly six years before ground controllers suddenly lost contact with it in December 2005. NASA had given up on the satellite and declared the mission over. But in January of this year, an amateur radio astronomer in Canada accidentally “rediscovered
” the spacecraft with his homemade satellite detector, and NASA was able to re-establish radio contact with it, albeit very weakly.
News of the satellite’s recovery was of particular interest to some UMass Lowell scientists: One of the scientific instruments that IMAGE is carrying onboard is the Radio Plasma Imager
(RPI), which was designed, built and operated by researchers at the university’s Space Science Laboratory
(formerly the Center for Atmospheric Research).
“It is still too early to say about the status of RPI, given that NASA is trying to understand the overall health of the satellite,” explains Song, who directs the Space Science Laboratory (SSL). “It is like assessing a person’s ability after a massive stroke and being in a vegetative state for 12 years. Our instrument is one of the satellite’s most important organs.”
“This is the most amazing thing I have ever heard in space research,” says Song. “Anything can happen in space, and sometimes it exceeds our wildest imagination.”
Exploring Earth’s Magnetosphere
IMAGE was designed to study Earth’s magnetosphere
, the vast region of space surrounding our planet that is filled with space plasma (mainly electrons and positive hydrogen ions) and extends some 600 to 50,000 miles above the ground.
RPI’s goal was to characterize that plasma using radio waves from 3 kilohertz to 3 megahertz. By observing the radar echoes reflecting off the plasma, RPI could locate regions of various plasma densities and features. And by fitting computer models of the magnetosphere to those features, scientists could create a 3-D picture of the magnetosphere’s structure and extent.
Prof. Emeritus Bodo Reinisch
of the Department of Environmental, Earth and Atmospheric Sciences
, the former director of the Center for Atmospheric Research, was the principal investigator for RPI when it launched. Other members of the science team included Song and Ivan Galkin of SSL, as well as investigators from NASA’s Goddard and Marshall Space Flight Centers, Southwest Research Institute, Rice University and Stanford University.
“RPI was the first active radio experiment flown into the magnetosphere,” says Reinisch. Unlike other space instruments that measure plasma density at the location of the spacecraft, RPI was able to instantaneously measure the plasma distribution along an entire geomagnetic field line from one hemisphere to the other.
“No other instrument is able to do this. RPI used two crossed wire antennas that measure 500 meters from tip to tip. They are arguably the longest antennas ever deployed in space,” notes Reinisch.
A new magnetosphere model was developed based on RPI measurements, and the erosion of the magnetosphere during solar storms as well as the time it takes for plasma to refill after the storms was also measured, he says.
UMass Lowell received more than $12 million from NASA to build RPI, and it paved the way for many more research grants that followed. “Thanks to data gathered by RPI, four Ph.D. theses were completed at UMass Lowell and more than 60 papers in refereed journals have been published worldwide,” says Song.
Next Mission: Mitigate the Threat of ‘Killer Electrons’
Because of the success of RPI and the engineering capability demonstrated by UMass Lowell in the IMAGE mission, the Air Force Research Laboratory awarded SSL a $5 million grant to build a high-power space radio-wave transmission experiment for its DSX mission
to the Earth’s radiation belt. The DSX’s objective is to test a new idea that uses “wave-particle interaction” to mitigate harmful, extremely high-energy particles called “killer electrons
“These electrons, traveling at nearly the speed of light, are capable of damaging satellites and threatening the health of astronauts in orbit,” says Song.
The DSX satellite is scheduled to be launched later this year using a SpaceX Falcon Heavy, the same rocket booster used by SpaceX CEO Elon Musk to send his Tesla Roadster and Starman
into orbit in February.