Pegasus launches ICON space science mission
LAS CRUCES, N.M. — A long-delayed NASA space science satellite finally reached orbit Oct. 10 on a Pegasus rocket, a launch vehicle with an uncertain future.
The Pegasus XL rocket was released from its L-1011 carrier aircraft at 9:59 p.m. Eastern off the Florida coast and ignited its motors to ascend to orbit. Its payload, the Ionospheric Connection Explorer, or ICON, was released from the upper stage in low Earth orbit about 11 minutes after ignition.
NASA scheduled the launch for 9:30 p.m. Eastern but a communications glitch shortly before the planned release led to a half-hour delay. NASA scrubbed a launch attempt Oct. 9 hours before the plane’s takeoff from Cape Canaveral because of poor weather in the area.
Those delays, though, pale in comparison to issues with the Pegasus rocket that delayed its launch by about two years. That included a case where the rocket’s rudder position indicator became active, but only while the rocket was attached to the aircraft at cruise altitudes.
“We saw some things on our previous launch attempt that none of us were comfortable with, and we decided to stand down and go address those,” said Phil Joyce, vice president of space launch programs at Northrop Grumman Innovation Systems, at a pre-launch briefing Oct. 8. That previous launch attempt, also based out of Cape Canaveral, was in November 2018.
Joyce described the issue with the rocket as “one of the most challenging that I’ve seen.” He said the rudder on the rocket’s first stage showed “noise spikes” in its position indicator, only at altitude. “We didn’t understand those, but they were significant enough that we were concerned if, we launched with that condition present, that those noise spikes could couple into our control system and cause a bad day.”
He said that the problem could be linked to “several causal factors” that the company addressed by modifying electronics in the rocket as well as making a feedback circuit more robust to the environmental conditions of flight. That was tested on several captive carry flights, including a ferry flight from Vandenberg Air Force Base in California to Cape Canaveral, giving Northrop and NASA confidence they had resolved the problem.
The ICON launch was the 44th Pegasus mission in the rocket’s nearly three-decade history, but also only the fourth launch in the last 10 years. Despite the growing interest in small satellites, for which Pegasus was designed to launch, the vehicle has only been used in recent years for a handful of NASA science missions.
Even that limited business is now in jeopardy. In July, NASA awarded a contract to SpaceX for the Falcon 9 launch of the Imaging X-Ray Polarimetry Explorer (IXPE) astronomy mission, a smallsat that had been designed to be compatible with the Pegasus XL rocket. The value of the Falcon 9 IXPE contract was $50.2 million, less than the $56.4 million value of the 2014 contract NASA awarded for the ICON launch on a Pegasus XL, even though the Falcon 9 is a far larger vehicle.
At the pre-launch briefing, Joyce acknowledged that the company has no future missions on the Pegasus XL manifest. He did note there are two Pegasus rockets at Vandenberg “in a pretty advanced state of integration” that are available. “We’re talking to several potential customers for those,” he said.
Those two rockets, industry sources say, were being built for Stratolaunch, the venture backed by the late Paul Allen that planned to launch Pegasus rockets from the giant aircraft it developed. That plane flew a single test flight in April, but the lack of activity since has fueled speculation that the company may be winding down.
The 288-kilogram ICON satellite will study the interaction between space weather and terrestrial weather in the ionosphere that could improve modeling of space weather activity. “It’s this region where these two weather systems, space weather and terrestrial weather, are mixing together,” said Nicola Fox, director of NASA’s heliophysics division, at the Oct. 8 briefing. “It’s really, really important for us to go understand that.”
Despite the delays, Fox said that the mission remained with its cost cap of $252 million. NASA didn’t make major changes to ICON during the extended launch delay, but she said the mission should benefit from data from other, complementary missions collected during this time. “If anything,” she said, “we’re a little more excited about ICON is going to bring to us.”