QB50: Science from Above

testThis past May, the Climate and Space Sciences and Engineering department saw two more small satellites deployed from the International Space Station (ISS) into orbit. The two tiny CubeSats, named Columbia and Atlantis, are part of the European QB50 mission to deliver a “swarm” of science satellites into the Earth’s upper atmosphere.

The QB50 mission consists of a network of 36 university-built CubeSats launched to an orbit in the largely unexplored lower thermosphere, roughly 400 kilometers above the Earth’s surface. The first 28 QB50 satellites were delivered to the International Space Station (ISS) for scheduled deployment in pairs during the month of May. The remaining eight CubeSats were deployed from atop an Indian Space Research Organization (ISRO) Polar Satellite Launch Vehicle (PSLV) in June.

The U-M QB50 CubeSats take their place alongside the eight satellites of the CLaSP-led CYGNSS mission (launched December 2016), and will bring the department’s total number of operating spacecraft to 10. CLaSP Professor Aaron Ridley is the Principal Investigator for the Columbia and Atlantis CubeSats.

The QB50 project is managed by the Von Karman Institute for Fluid Mechanics in Belgium, and consists of a consortium of 15 partners from leading universities and research institutes from 23 countries. The mission’s goal is to demonstrate the feasibility of launching a networked group of small spacecraft capable of performing first-class science.

A LOW-COST ALTERNATIVE

The project grew out of a need for in-situ scientific measurement in the Earth’s upper atmosphere. Our atmosphere is at its highest density (thicker with air particles) near the surface of our planet, and becomes less dense, or thinner, with increased altitude. This means that spacecraft at the highest altitudes can circle the Earth indefinitely, while lower satellites can remain in orbit for only a few years. But the lowest satellites travel through an environment that’s considerably denser, and will have a much shorter lifespan, approximately six months, before they’re pulled low enough to burn up in the atmosphere.

For perspective, the ISS orbits the globe at roughly the same altitude as the QB50 satellites. But because the space station is much larger, its orbit declines much more rapidly and it must be “boosted” up each month to prevent it from falling into the atmosphere.

As researchers considered their options, it was clear that traditional larger satellites were simply too expensive for such a short lifespan. For decades, close-up scientific observation and measurement in this part of the atmosphere was out of reach.

The eventual development of CubeSats provided a solution to this dilemma. These small, cube-shaped satellites are built to standard dimensions of 10x10x10 cm cubic units (or “U”). This translates into a container approximately four inches on a side with a volume of about one quart, and generally weighing less than 1.33 kg (3 lbs.) per U. CubeSats can be a 1U cube, or combined into configurations of 2U, 3U, or even 6U in size. Each CubeSat carries one or more specialized scientific instruments that communicate atmospheric data back to Earth.

Best of all, CubeSats can be built and launched in clusters for a fraction of the cost of traditional industrially engineered satellites. Which makes these miniature spacecraft the most viable option currently available for conducting scientific measurements within the lower thermosphere.

U-M QB50 CUBESAT SCIENCE

Both Atlantis and Columbia carry a Flux-Φ-Probe Experiment (FIPEX) instrument that measures the behavior of oxygen over time. The element is dominant in the thermosphere, and therefore a key parameter to the correlation and validation of atmospheric models.

Professor Ridley and his team will use data taken from FIPEX to observe the dynamics of the upper atmosphere. Specifically, Professor Ridley intends to observe how our Earth atmosphere expands and contracts in reaction to solar activity (such as increases in the northern lights, geomagnetic storms, coronal mass ejections, etc.). Professor Ridley sees the CubeSats as “space buoys” that, similar to their ocean counterparts, could help provide early warning of potentially disruptive space weather headed toward Earth.

Through these observations, the U-M team hopes to gain a better understanding of the ebb and flow of upper atmospheric behavior, and potentially contribute to a more comprehensive model of the interaction between the Earth’s space environment and that of its star.

- EJ Olsen