CYGNSS Pegasus launch
An Orbital ATK Pegasus XL launches Dec. 15, placing eight CYGNSS hurricane forecasting satellites into orbit. Credit: NASA

WASHINGTON — In its first flight in nearly three and a half years, an Orbital ATK Pegasus XL rocket successfully launched eight satellites for NASA Dec. 15 that will be used to improve hurricane forecasts.

The L-1011 aircraft carrying the Pegasus XL took off from Cape Canaveral Air Force Station in Florida at 7:38 a.m. Eastern and released the rocket 59 minutes later, at an altitude of about 11,900 meters. The rocket ignited its solid-fuel motor and began its ascent, releasing its payload of eight satellites over a 90-second period about 13 minutes after launch.

“For Pegasus, it was overall a beautiful day,” said Tim Dunn, NASA launch manager for the mission, in an NASA TV interview after satellite deployment. “All three stages performed beautifully: no issues at all with the Pegasus launch vehicle performance.”

The launch was previously scheduled for Dec. 12 but scrubbed after the L-1011 took off when a hydraulic pump that is part of the launch vehicle release system on the aircraft malfunctioned. The launch was rescheduled for the Dec. 14 after repairing the pump, then delayed again to Dec. 15 because of a software issue.

The eight satellites deployed by the Pegasus will make up NASA’s Cyclone Global Navigation Satellite System (CYGNSS). The satellites, designed and built by the Southwest Research Institute and University of Michigan, weigh 28.9 kilograms each and will operate in a 510-kilometer orbit inclined 35 degrees to the Equator. NASA reported late Dec. 15 that it had established contact with all eight satellites as they made passes over ground stations.

The CYGNSS satellites will detect Global Positioning System signals reflected off the oceans in tropical regions, measuring the amount of scattering of the signals to calculate the roughness of the oceans and thus the wind speeds at the surface. That data, scientists believe, will help improve models of hurricane formation and increase the accuracy of forecasts of their development.

“CYGNSS is a tool that will provide us 24/7 coverage of the tropical cyclone zone, and it will improve our knowledge of how hurricanes grow so that we can better prepare and protect the people in the path of each hurricane as it comes,” said Christine Bonniksen, program executive for the mission at NASA Headquarters, during a pre-launch briefing about the mission in November.

For Orbital ATK, the mission was the 29th consecutive successful Pegasus launch dating back to 1997, but the first since a June 2013 launch of NASA’s Interface Region Imaging Spectrograph mission. Despite a surge in interest in recent years in small satellites, and efforts by a number of companies to develop their own dedicated small satellite launch vehicles, Pegasus has not attracted business beyond the occasional NASA mission.

One factor in that lack of activity is the relatively high cost of the Pegasus. The launch services contract NASA awarded to then-Orbital Sciences Corp. in March 2014 for the CYGNSS mission was valued at $55 million. That contract covered the launch itself, spacecraft processing, and related services.

Orbital ATK has a contract for at least one more Pegasus XL launch, of NASA’s Ionospheric Connection Explorer mission, scheduled for mid-2017. That contract, awarded in November 2014, is valued at $56.3 million.

The company also announced a partnership with Stratolaunch Systems Oct. 6 under which Orbital ATK will provide “multiple” Pegasus XL rockets to be launched by Stratolaunch’s giant aircraft currently under construction. The companies did not disclose details about the partnership, including the number of rockets Orbital ATK will supply or when those launches would begin.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...