Cubesat offers template for future astronomy missions

The first NASA-funded small satellite for exoplanet science is continuing to gather data well beyond its expected lifetime. The Colorado Ultraviolet Transit Experiment, known as CUTE, a six-unit cubesat equipped with a telescope to funnel data to a spectrograph, traveled to sun-synchronous low-Earth orbit in September 2021 as a secondary payload on the NASA- U.S. Geological Survey Landsat 9 Earth-observation mission. CUTE was designed to operate in space for at least eight months. Twenty-seven months later, the satellite’s onboard instruments still are observing the dramatic atmospheric loss of “hot jupiters,” gas giants orbiting very close to bright stars. “This atmospheric escape is incredibly fast,” said Kevin France, CUTE principal investigator at the University of Colorado’s Laboratory for Atmospheric and Space Physics (LASP), which assembled, tested and operates the satellite. “The materials are coming out so fast that they are dragging all the heavy elements out of the atmosphere with them.” Based on CUTE’s success, two additional NASA-funded, LASP-led missions have adopted similar mission and instrument designs. “CUTE’s been a great success, particularly given that we didn’t really know if we could do it for the amount of money that we proposed,” France told SpaceNews at the American Geophysical Union conference here. Lessons learned from CUTE are helping researchers “figure out how to build small spacecraft, how to build small instruments and how to have a student-led team,” France said.

The Colorado Ultraviolet Transit Experiment, known as CUTE, is a cubesat launched in 2021 to characterize the composition and mass-loss rates of exoplanet atmospheres. Credit: University of Colorado Laboratory for Atmospheric and Space Physics

Smallsat Astronomy

The budget for developing, assembling and operating CUTE through the summer of 2024 is about $5.5 million.

“At this cost, we’re still figuring out how to make things work,” France said. “So, working and doing science is batting above your average.”

The missions mimicking CUTE are 12-unit cubesats Sprite and Mantis.

Sprite, which stands for Supernova remnants Proxies for Reionization and Integrated Testbed Experiment, is scheduled for launch in 2024. The $4 million mission will study how gas and dust is processed in galaxies and how energetic ionizing radiation is transported from stars to the intergalactic medium between galaxies.

Mantis, short for Monitoring Activity from Nearby sTars with uv Imaging and Spectroscopy, is an $8.5 million campaign to observe how high-energy radiation from stars influences the habitability of planets.

Ingenuity and Chance

CUTE remains operational more than two years after launch thanks to ingenuity and luck.

The tiny satellite was sent into orbit at a higher altitude than mission planners expected. As a result, CUTE is expected to reenter Earth’s atmosphere in 2027, instead of late this year as originally scheduled.

Additional time in orbit means extra wear and tear on hardware.

“Every time we have a problem, we figure out a new way to operate the spacecraft,” France said.

When the satellite’s primary and backup memory storage cards failed, for example, mission operators learned to communicate directly with CUTE’s scientific payload.

“We send the data down directly from the science payload to the ground and we bypass the spacecraft altogether,” France said.

Distant Galaxies

Cubesats have been widely adopted for civil and commercial space missions since LASP researchers proposed CUTE in 2016.

At the time, “we were beginning to believe we could study the sun and Earth’s upper atmosphere with cubesats,” France said. “But the idea that we could be pointed at targets that are 300, 400 light years away and do high-precision astronomical measurements from the cubesat was ambitious.”

Now that CUTE has shown the potential, small satellites could play key roles in observing distant galaxies, black holes “and all the other things that we’re interested in studying,” France said.