By Ann Roosevelt
The Air Force has discovered and produced a fix for a timing issue found on a Minotaur IV launch vehicle that delayed a planned July 8 launch for the Space Based Space Surveillance Satellite (SBSS) to a future, unspecified date, officials said yesterday.
The anomaly occurred in “one test out of 1,000,” on a Minotaur IV vehicle now in development, Tim Kettner, Orbital Sciences Corp.’s chief engineer for the Minotaur Program, said in a teleconference. “No similar occurrence was noted for SBSS in over 4,000 (test) runs.”
SBSS is to give the Air Force its first full-time, space-based surveillance of satellites and debris in Earth orbit, a job currently done by ground-based systems.
“SBSS is the cornerstone of Air Force situational awareness in the future,” SBSS Launch Mission Director Air Force Col. J.R. Jordan, said in the teleconference.
Orbital [ORB] discovered the anomaly in May during preliminary testing for the Space Test Program S-26 mission, which would follow SBSS.
Col. Michael Moran, commander, Space Development and Test Wing at Kirtland AFB, N.M., said: “Our investigation pointed to a problem with the common launch vehicle software that’s used on all our missions.”
Thus, the investigation required an assessment of impacts to the SBSS test launch.
“To date, the government and industry team performed troubleshooting, developed the needed software fixes and are now beginning formal testing of the software updates,” Moran said.
When the Air Force is confident the issue is resolved and demonstrated through successful testing, a new launch date will be established, he said.
“The delay to the launch of SBSS reflects the absolute and unwavering focus of the entire government and industry team on mission success,” Moran said.
Orbital initially examined the possibility of a test equipment issue or a problem unique to the characteristics of the S-26 mission. When no root cause was identified in these areas, it became an issue for the SBSS mission in mid-June. Further investigation discovered a timing issue in the flight software, a software revision has been issued and formal testing is under way, Kettner said.
Meanwhile, the Minotaur IV stack sits on the pad at Vandenberg AFB, Calif., while the satellite is in a security facility at the base, Jordan said. “We will not stack the satellite on the rocket until we know we have this problem behind us and we think it will take us about three weeks.”
Once the software completes factory testing and is loaded on the launch vehicle, full system testing will be done, Moran said.
Kettner said another 2,000 test runs will be done over and above typical qualification of flight software, in addition to “real time closed loop test to verify that the timing conditions we believe are at the root of this are adequately stressed and demonstrated robust for flight.”
Moran said other Air Force programs using Minotaur launch vehicles after SBSS include the Space Test Program S-26, the L-66 mission, Tactical Satellite IV, a Defense Advanced Research Projects Agency hypersonic technology vehicle mission, and the Operationally Responsive Space-1 (ORS-1) spacecraft.
“Right now, it’s premature to assess the impact to the schedule of these flights until we get SBSS issue behind us,” he said. “Then assess impacts to the rest of the launch schedule, if any.”
“We believe that the timing issue is in the low level software that’s common to all Minotaur 4 vehicles. It would be common to the entire Minotaur family,” Kettner said. “Since the software change that we’re making is in code that’s common to all of these missions, we will be making this robustness improvement to all of the missions that are currently in work.”
The mission assurance process purposely ferrets out problems, Jordan said, and the team was pleased “the process did that and that we have an opportunity to fix that problem not just for SBSS launch but for the entirety of the Minotaur family.”
Boeing [BA] is the prime contractor for SBSS, while Ball Aerospace [BLL] designed, developed, built, integrated and tested the satellite.