Undergraduates build and launch a satellite to measure atmospheric drag

by Bryce Mitsunaga
Tuesday, October 1, 2013

In 2000, the International Space Station (ISS) was the victim of a severe geomagnetic storm: a wave of solar particles hit Earth’s atmosphere, warming it, expanding it, and increasing its density. In just a few days, the space station's elevation dropped several kilometers. The incident received a lot of attention in the media, but thousands of satellites experience changes in altitude during solar storms. Their controllers — including NASA and the Air Force’s Space Command — rely on imperfect models to predict the satellites' locations, and it costs time and money to reposition these devices.

Now, a group of students at the University of Colorado in Boulder (CU) has created a satellite that will help scientists improve the models of how atmospheric drag and density affect satellite position during solar events. The Drag and Atmospheric Neutral Density Explorer Satellite (DANDE) entered Earth’s orbit on Sunday, representing the labor of 150 students over seven years.

CU graduate students and faculty created the original design for DANDE in 2007 with a grant from the U.S. Air Force Office of Scientific Research; it won the University Nanosat Program 5 competition in 2009. The Colorado Space Grant Consortium, a statewide organization funded by NASA’s Space Grant Program, supervises the project from its headquarters in Boulder.

But a student team comprising mostly undergraduates has made the lion’s share of day-to-day design decisions, from drafting and construction to environmental testing, writing software and preparing the ground team. DANDE’s current co-managers — CU senior astronomy major Miranda Link and junior aerospace engineering major Brenden Hogan — have been with the project since 2011, leading a team that fluctuates between five and 30 people.

According to Link, these fledgling engineers have paired two instruments in a unique combination. DANDE’s first main component is its accelerometer; its second is its neutral mass spectrometer, which measures the concentration, velocity and direction of particles in the upper atmosphere. With these data, scientists can solve Stokes' law, an expression of the drag force exerted on an object, whether it be the ISS or "space junk." Link says current drag models are "mostly just averages over large portions of the atmosphere." DANDE’s measurements will be applied to updated models. Initially, a small cadre of CU faculty interested in satellite drag will handle the data, with the circle gradually growing to include CU grad students and researchers from other institutions, says Scott Palo, a professor of aerospace engineering sciences at CU. Los Alamos National Labs, among others, have shown interest in collaboration, Palo says.

One of the highlights of the project is that undergraduates are making a significant contribution to science, says Palo, also DANDE’s co-principal investigator. "There’s not often we find a sweet spot where students can do something that really is new and hasn’t been done before."

Link, Hogan and nine of their current team members traveled to Vandenberg Air Force Base in California for the launch. The satellite was aboard one of the Falcon rockets from SpaceX — a private company that transports cargo into orbit. DANDE will circle in orbit at altitudes between 325 and 400 kilometers. After some initial troubleshooting, Hogan says "our team will focus on making sure that [the data are] not wildly impossible or anything that would indicate a failure," Hogan says. He and Link will continue to train student operators to monitor DANDE’s communications.

Their vigil will last a year and a half as solar radiation slowly degrades DANDE’s instruments. Twenty years from now, its 50-kilogram husk has been designed to disintegrate upon re-entry into Earth’s atmosphere, as most small satellites do. For now, everything appears normal. On the afternoon of Sept. 29, DANDE returned its first location beacons, high above Russia and Germany.

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