CubeSats prove their value for scientific missions

Just a few years ago, the astronomy and heliophysics communities were wary of whether CubeSats could reliably obtain scientific data. But these bread-sized satellites have proven their ability to render useful data.

At the April 2019 meeting of the American Physical Society, to be held April 13-16 in Denver, Colorado, Christopher S. Moore, Harvard-Smithsonian Center postdoctoral fellow for the group's Astrophysics of the Solar and Stellar Radiography Group will describe how CubeSats, a miniature solar X-ray spectometer (MinXSS), measures the X-rays of the sun. These were the first solar-science-driven CubeSat missions executed on behalf of NASA's Science Missions Directorate.

As he will explain at the meeting, Mr. Moore was one of the many graduate students who contributed to MinXSS during his lifetime. He worked on the MinXSS CubeSats as part of his Ph.D. at the University of Colorado at Boulder.

"This work has shown that these relatively inexpensive small servers, ranging from $ 1 million to $ 2 million for MinXSS – can access data that fill a specific niche and correspond to large, much more expensive satellites, and contribute to major scientific investigations. , "said Moore.

MinXSS-1 was launched in December 2015 as part of the Orkital ATK replenishment mission to launch the Atlas-V Cygnus OA-4 to the International Space Station, where it was deployed for approximately 12 months on the ground. The second version, MinXXS-2, was launched on the SpaceX Falcon 9 as part of Spaceflight SSO-A: SmallSat Express in December 2018 and deployed for an orbit and a four to five year operation.

Science-based CubeSats are low-cost, short-lived satellites designed to perform specific scientific observations and measurements. MinXSS, for example, features economical components, such as an extensible measuring tape serving as a radio antenna.

Its scientific payload consists of a flexible X-ray spectrometer that has been modified to be compatible with the hostile environment of space. MinXSS also ships silicon-based photometers for other soft x-ray and visible light measurements.

The MinXSS-1 (the first of two twin satellites), funded by NASA, was the initial test of Blue Canyon Technologies XACT, a miniaturized attitude determination and control system. The success of MinXSS-1 and XACT gave rise to the 2016 SmallSat Award of the Mission of the Year.

"The MinXSS measures solar X-rays between 0.5 and 12 kiloelectrons-volts with moderate spectral resolution, which includes the poorly observed bandpass of 0.5 to 2 keV," Moore said. "This spectral region is very informative of solar atmospheric plasma conditions for temperatures above 2 million Kelvin present in solar flares and during rest (dormancy)."

The data collected by MinXSS have been consistent with the inferences of large satellites. "The MinXSS data will help us understand the physics behind solar flares," Moore said. "Soft x-rays contain information about the temperature, density, and chemical composition of materials in the sun's atmosphere, allowing scientists to determine how events such as torches and other processes heat materials. surrounding in the crown, the atmosphere of the sun. "

Variations in solar X-ray emission are strongly correlated with large-scale magnetic features called active regions. "These active regions appear as light loops in soft X-rays, but appear as dark spots on the solar surface (the photosphere), so they are called" sunspots. "MinXSS data can help directly limit the temperature of the plasma of these relatively quasi-static characteristics, "said Moore.

CubeSats offers "excellent training opportunities for future leaders in the fields of technology and science, as undergraduates, graduate students and post-docs typically play a central role in the design, development, testing, mission operations and scientific analysis, "said Moore. "More than 40 graduate students from the University of Colorado at Boulder have contributed to MinXSS throughout the project."

Because of CubeSat's recent successes, NASA and the National Science Foundation are now offering new funding opportunities to fund science-based CubeSats directly.