The last time someone photographed the exosphere, the outermost layer of Earth’s atmosphere separating it from outer space, was in the 1970s from the surface of the Moon.
This is a problem for two reasons, said Brian Walsh, an associate professor in Boston University’s College of Engineering.
“The exosphere is necessary for life, and so if we understand how it works and when it grows or shrinks, that could help us understand how planets become habitable or not habitable,” he said. “More directly to us … pretty much everyone at this point in Boston or in the Greater Boston area, relies on space almost every day.”
Walsh said every credit card transaction that someone makes relies on space — and the same goes with using a GPS.
The Carruthers Geocoronal Observatory, a NASA satellite built by researchers from BU and the University of Illinois-Urbana Champaign, officially launched Sept. 24 with the goal of resuming the study of the Earth’s exosphere and its changes.
The observatory consists of two main parts.
The primary telescope, pointed at the Earth, will measure the exosphere’s shape, size and density.
On the opposite side is COSSMo, or the Carruthers Observatory Student Solar Monitor, built by BU’s Space Physics and Technology Lab. The device, which went operational and began collecting data Oct. 3, faces the sun, measuring its rays’ intensity.
Walsh said the COSSMo’s sensors observe X-rays, Lyman Alpha waves — a type of ultraviolet light emitted by the Sun — and charged particles.
By combining COSSMo’s measurements with pictures of the exosphere, Walsh said, scientists can determine how the exosphere changes as the sun’s intensity also changes.
“By knowing when the sun gets brighter or dimmer, and at the same time, if the exosphere gets expanded or compressed, you could put those together and understand cause and effect,” he said.
COSSMo was built over the course of four years and was led by Walsh, who served as principal investigator, and Van Galaxy Naldoza, a mechanical engineering PhD student researcher who served as the student lead.
Walsh said the project began when NASA approved a proposal for a spacecraft that could study Earth’s outer atmosphere.
“We’re a race of creatures that are very quickly becoming more and more space dependent,” he said. “The measurements that this mission is going to be making is going to help us use the space environment better, specifically how spacecraft drag works.”
The project will last two years, Naldoza said, but the satellite will continue recording measurements so long as it remains functional and the team has the resources to maintain it.
Building COSSMo was a complicated process, he said. The team had to make sure the instrument could view specific light wavelengths and fulfill various size, weight and power requirements — all while ensuring its development did not delay the launch of the Carruthers mission, Naldoza said.
Since COSSMo would be going into space, the stakes were particularly high, Walsh said. Therefore, the team had to make sure everything about COSSMo was perfect, he said.
“You’ve got to build something that works in a lab, but you also have to make sure it’s robust, and it can work without failure in space,” Walsh said. “Once you build something and put it in space, you can’t go back up and fix it. It’s done, so it has to be perfect.”
Naldoza said there appears to be no major problems with the spacecraft, and the data COSSMo is sending seems to match that of other satellites.
Ramiz Qudsi, a research scientist at the BU Center for Space Physics, said it was a “huge relief” to see COSSMo go operational.
“The fact that there was any data coming in was just so exciting because nothing is ever guaranteed in space,” he said. “So the fact that Cosmo actually did turn on, and not only turned on, but also started sending us data, was just amazing.”
COSSMo’s launch is only one of the lab’s many projects. Recently, they worked on LEXI, a telescope that landed on the Moon earlier this year as part of NASA’s Blue Ghost Mission 1, and CuPID, a satellite that launched in 2021.
“It’s incredible how well the whole lab is doing,” Qudsi said. “It’s a testament to the leadership that Brian had. It’s just wonderful to see.”
