If you’re a parent of a certain age, you know the bittersweet feeling that comes when a child leaves home, capping a decade or two of your blood, sweat and tears.
Cliff Lopate must be feeling that way about a satellite.
“In 2004, we began the formulation phase of the design of an instrument. . . . But the first designs for scientific testing were put out around 1999 (or) 2000,” said Lopate, a research associate professor at UNH and principal investigator on the Energetic Heavy Ion Sensor, which was launched into space Nov. 19 as part of a weather satellite called GOES-R.
For as long as it takes a child to go from birth to high school diploma, Lopate has been working on a device to tackle the difficult job of measuring very rare but relatively powerful heavy ions zipping around in deep space. It hasn’t been his only job over the years – being a parent never is – but it has always been part of his research life and those of colleagues.
Before we get to the science, why did it take so long? Because, Lopate said, this is an operational satellite designed to do a specific task for a specific reason, rather than a research satellite designed to answer a question. Incidentally, UNH says this is the first time one of their professor’s work has been part of an operational satellite, although scads of UNH folks have been part of research satellites.
“The mission requirement was to put it up in orbit and be able to store it in fairly significant radiation environment for up to five years, then turn on, and it had to work correctly for 10 years. Most science missions generally have time scales of one to three years – this basically has to work for up to 15 years without failing,” said Lopate. “Product assurance requirements on operational satellites are considerably more stringent than on scientific missions. There are more reviews of design; more and different types of prototyping; a lot of extra testing; some redundancy.”
UNH won the bid and subcontract to Assurance Technology Corp. in Massachusetts, which subcontracted to NASA to make an entire suite of experiments riding on the satellite. Lopate said the UNH award was about $11.6 million, roughly a million dollars a year over 12 years of funding, and future funding will cover post-launch analysis.
Lopate is a brave soul, because he attended the launch at Cape Canaveral even though, like everybody in space science, he is aware that launches sometimes go wrong, obliterating years of work in an instant: “I know people who have lost a satellite.”
“It’s really nerve wracking to stand there and know that your instrument is sitting on top of high explosives, whose sole purpose is to explode in a controlled manner,” he said. “You find you’re holding your breath – about 20 seconds later, after the first stage gets detached, then you breathe again.”
And perhaps he also felt a little pang of separation anxiety as the package of instruments went aloft.
OK, enough parenting parallels. What about the science?
GOES stands for Geostationary Operational Environmental Satellite, with “geo-stationary” meaning it sits about 26,000 miles above the Earth, an orbit that keeps it over the same place as the planet revolves. You may have heard of GOES because the National Weather Service uses them for weather forecasting – the latest is called GOES-R, getting the 18th letter as a suffix to differentiate it from 17 previous launches or attempts – but they also study other things, including space weather.
Space weather mostly means “solar wind,” the charged particles emitted by the sun that can affect satellites, our own atmosphere, and, of course, any astronauts. It has been studied for a long time, but what I didn’t realize is that we haven’t been studying all of the wind, but mostly the low-energy portions made of separate protons and electrons. This is the bulk of space weather, but perhaps not the most significant part.
“The current GOES satellites were last updated technologically in mid-1990s. We now have a different understanding of what we want to monitor,” Lopate said. “It has become clear that heavy ions pose an increased risk to systems, because heavy ions deposit considerably more energy than protons and electrons do. One carbon atom would put 36 times energy as one proton – one iron atom put 256 times energy as one proton. . . . It’s so energetic there’s no real way to shield it.
“In 2004, when NOAA put together list of what they wanted, they wanted an energetic heavy ion sensor. We won the bid,” he said.
The UNH system measures the atoms that zip around space up through nickel. It uses a silicon wafer detector, made of semiconductors.
“When ionizing radiation is deposited, it knocks an electron up to induction band, a charge pulse is generated. The size of the charge pulse is directly proportional to energy that’s out there,” said Lopate.
The information gathered by the Energetic Heavy Ion Sensor will help us understand space weather and predict when dangerous pulses are headed our way from the sun, which is important to protect satellites and people above the atmosphere. If Elon Musk takes us to Mars, we’ll want to know this stuff.
In the meantime, Lopate waits to see how his baby does now that it has gone out into the world on its own. I wonder if he carries pictures of it in his wallet?