Studying Cosmic Rays: Mines-built space observatory launched into the stratosphere
A NASA space observatory put together by Colorado School of Mines researchers launched from Wanaka Airport in Otago, New Zealand, the afternoon of April 24, 2017, in a pioneering attempt to observe ultra-high-energy cosmic rays entering Earth’s atmosphere.
The Extreme Universe Space Observatory Super Pressure Balloon flew at 110,000 feet, and was designed to travel for up to 100 days. Researchers hoped to gain insight into the origins of the highest-energy subatomic particles known to exist in the universe, and how they traveled to Earth.
Mines Physics Professor Lawrence Wiencke, co-project leader, oversaw a team of students and faculty in assembling the gondola, as well as integrating the instrumentation to allow the transmission of data. The observatory underwent testing at NASA’s scientific balloon facility in Palestine, Texas, last November and was shipped to New Zealand in December. The observatory passed its final tests March 23.
“Amazing,” Wiencke said about the successful launch. “The 1,000-foot flight train was released smoothly from the ‘pin’ on the end of the launch crane and the entire 10,000 pounds of balloon, parachute and EUSO-SPB payload rose nearly straight up.” The balloon reached 109,000 feet about three hours after launch—a critical milestone. The observation of these cosmic rays is a challenge because of their rarity. At the highest energies, which are well beyond the capabilities of man-made particle accelerators, fewer than one cosmic ray enters Earth’s atmosphere per square kilometer per century.
“High-energy cosmic rays have never been observed this way from space, and space offers the biggest view of the atmosphere,” Wiencke said. “This is a pioneering opportunity for us,” he added.
“We know that these extremely energetic particles travel from faraway galaxies to reach the Earth,” said Angela Olinto, principal investigator and professor at the University of Chicago. “We need to observe a significantly larger number of these cosmic messengers to discover what their sources are and how particles interact at these energetic extremes.”
When such a cosmic ray reaches Earth, the interaction with nitrogen molecules in the atmosphere creates fluorescent light proportional to the energy of the particle.
Instrument subsystems were shipped to Mines, where the detector was assembled and tested. Mines team members Adjunct Professor William Finch and machine shop head Randy Bachman, working with counterparts at NASA, designed a mechanical exoskeleton structure. Undergraduate engineering physics students Rachel Gregg and Zach Polonsky performed much of the fabrication.
The Mines group led optics testing and successful field tests using lasers in the Utah. Wiencke, postdoctoral researcher Simon Bacholle, PhD student Johannes Eser and Gregg traveled to the Wanaka launch site in February to prepare the instrument for launch along with other members of the international collaboration. Eser was responsible for instrument operations during launch, while Gregg was in charge of critical steps on the launch day checklist. Bacholle returned to Mines and set up a remote operation center, while former Mines postdoc Lech Piotrowski was responsible for the remote operations center at the RIKEN institute near Tokyo.
Despite the successful launch, a leak in the balloon and a poor weather forecast prompted NASA to preemptively end the flight to ensure the greatest level of control and safety during the balloon’s descent. Yet, the balloon was still able to collect a great amount of data, and researchers will apply the lessons learned from this flight to future flights as they continue to develop this technology.