How are cubesats advancing astrophysics?

Cubesats are becoming more common. In low Earth orbit, they are becoming so prevalent that concerns are arising about space debris and interference with Earth-based observation. A less discussed aspect of cubesats is their applications in astrophysics research. Their small size allows for cost reductions that lower barriers to conducting such research. To learn more about how cubesats are advancing astrophysics research, we spoke to Paul Scowen, a professor at Arizona State University’s School of Earth and Space Exploration. He is working on the Star-Planet Activity Research CubeSat (SPARCS), a cubesat astrophysics mission.

What is SPARCS and how did you come to be involved in it?

SPARCS is a 6U cubesat equipped with a dual-channel FUV/NUV imaging photometer to stare at and measure the rate at which M-class stars flare. It is only the third such cubesat mission to be funded by the NASA Astrophysics Division. It is part of an expansion into the use of these platforms for astrophysical research. The point of the mission is to measure how often these M-class stars flare and how energetic those flares are. Findings will determine the impact of such flaring on the atmospheres of nearby exoplanets. This will in turn inform our understanding of whether those exoplanets would be capable of developing life in the face of such flaring.

I became involved as part of a team of researchers at ASU to help shape the design of the mission since I am an astronomical instrumentalist at ASU and have experience building astronomical cameras. The SPARCS mission is part of a growing focus at ASU in the School of Earth and Space Exploration to develop both the technology of cubesats and the science they might enable from space. Such science includes projects to measure the heat island effect from space and to detect permanently frozen water ice at the lunar poles.

How has the role of cubesats in astrophysics changed over the course of your career?

Cubesats have developed very quickly in the past ten years. They used to be vehicles or platforms primarily used to demonstrate technology in space. Now they feature in missions and host cameras and spectrographs for astronomical observations. The key development has been that of attitude control systems for cubesats. These systems can now deliver arcsecond-level stability over 10-minute timescales with the use of star trackers and reaction wheels. With this kind of enhancement, cubesats are now capable of long-term observational monitoring of astronomical targets for which we cannot get time with orbital facilities like Hubble.

This access to the time domain provides a niche capability of which many areas of astronomical science can take advantage. The rapid development of miniaturized technologies that fit this form factor continues. We can expect new capabilities to become available in just the next few years. One of the next major changes will be the development of constellation-based projects where multiple cubesats work together to make observations. We are also working on a pathfinder concept with partners at JPL and elsewhere to enable on-orbit assembly of a larger structure. The structure will provide a scanning millimeter-wave receiver to study the vertical composition of the Earth’s atmosphere. This will enable looking for climate variations. 

What are some particularly interesting areas of astrophysics research today?

The development of cubesats for astrophysics has been particularly active in the ultraviolet band. This is in part because you cannot do ultraviolet observations from the ground. It is also because technologies developed for the visible band have been leveraged to provide better coatings and detectors for the ultraviolet that we can now use. Three of the recently approved NASA Astrophysics cubesat missions address science from the ultraviolet. One looks at exoplanet transits through a spectroscope. Another maps the structure of the outskirts of galaxies in order to study how mass and energy are exchanged between galaxies and the intergalactic medium.

Other areas of science being aided by cubesats include studies of high-energy phenomena such as gamma-ray bursts or other transients. Cubesats can also be used to map the skies at various wavelengths in order to help detect structures and emissions of targets that have not been accessible before. The advantage provided by cubesats is to provide a particular level of access that is not too expensive or time-consuming. The typical price point for this class of mission – somewhere between five and ten million dollars – allows for cost reductions.