XL-Calibur telescope launches in balloon from Swedish Space Center

Posted on Tuesday, July 16, 2024 by RICHARD HARRIS, Executive Editor

Researchers at Washington University in St. Louis have successfully launched a balloon-borne telescope to study the mysteries of astrophysical black holes and neutron stars, two of the universe's most extreme phenomena.

XL-Calibur telescope launches in a stadium-sized scientific balloon from the Swedish Space Center, and will study black holes and neutron stars

The telescope, named XL-Calibur, was launched on July 9 from the Swedish Space Corporation’s Esrange Space Center, located north of the Arctic Circle near Kiruna, Sweden.

"We are excited to measure the polarization of the black hole X-ray binary Cyg X-1 to determine how matter swirls around a black hole before it falls in, liberating enormous amounts of energy in the process. We hope that our results will have some impact on the measurement of black hole spin," said Henric Krawczynski, the Wilfred R. and Ann Lee Konneker Distinguished Professor of Physics in Arts & Sciences, and the principal investigator for XL-Calibur.

Esrange, situated in the sparsely populated northern region of Sweden, provides an optimal location for NASA’s 2024 scientific ballooning campaign. "The location of the launch range and the stratospheric winds allow for excellent flight conditions to gather many days of scientific data as the balloons traverse from Sweden to northern Canada," stated Andrew Hamilton, acting director of NASA’s Balloon Program Office.

XL-Calibur represents a collaborative effort among scientists from the United States, Japan, and Sweden. The instrument incorporates parts built at WashU, a mirror from the Japanese space agency’s Hitomi mission, a gondola and pointing control mechanism from NASA’s Wallops Flight Facility, and a shielding device developed at KTH in Sweden. It is part of NASA’s scientific ballooning program, and the collected data will be publicly accessible through NASA’s High Energy Astrophysics Science Archive and Research Center.


(Photo: Nicole Rodriguez Cavero)

A scientific balloon the size of a stadium lifted the XL-Calibur instrument into the sky

During this mission, the XL-Calibur team aims to study the matter accretion process of the black hole Cygnus X-1 and gather data on how pulsars accelerate particles. The telescope's data can be analyzed independently or in conjunction with the Imaging X-Ray Polarimetry Explorer (IXPE) satellite.

"We now have IXPE results from 2-8 keV. Extending those results to 15-80 keV will allow for deeper tests of the models advanced to explain the IXPE results," added Krawczynski, who is also a member of the IXPE science team and a faculty fellow of the McDonnell Center for the Space Sciences at WashU.


(Photo courtesy of XL-Calibur team)

Scientists analyzing the data following the launch

The XL-Calibur telescope, weighing 3,500 pounds, is mounted on a gondola carried by a stadium-sized scientific balloon into the stratosphere, reaching an altitude of about 125,000 feet (38,100 meters) above the Earth's atmosphere.

This mission marks the second flight for XL-Calibur. Washington University received $1.5 million in NASA funding for the flight, with additional support from Japan and Sweden.

"Of course we would love to be in the air for as long as possible, to get as much data as possible! We had been aiming for at least 4 to 5 days of data-taking flight, but it really depends on the stratospheric winds, at any given point in time," said Ephraim Gau, a graduate student in physics in Arts & Sciences working on XL-Calibur and stationed at Esrange for the launch.


(Photo: NASA/SSC)

The XL-Calibur instrument was launched from the Esrange Space Center, operated by the Swedish Space Corporation on July 9t

"Regardless, this has the potential to be one of the most scientifically successful flights of XL-Calibur or its predecessors because of how well it complements recent results from IXPE. I would especially like to credit the many previous graduate students and post-docs - including Lindsey Lisalda, Andrew West, and Quin Abarr - who spent years working to make this experiment a reality," Gau said.

Viewers can follow XL-Calibur’s journey via NASA’s flight tracking maps available on their website.

The instrument is seen ascending shortly after its launch

XL-Calibur will gather data at an altitude of approximately 125,000 feet (38,100 meters), beyond 99.97% of the Earth's atmosphere.

(Photo: Nicole Rodriguez Cavero)


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