WASHINGTON — The failure of a Russian Progress spacecraft to deliver cargo to the International Space Station is unlikely to have a significant near-term effect on station operations, but will place a greater burden on upcoming resupply missions and could alter the cargo those missions carry.
A Soyuz-2.1a rocket carrying the Progress M-27M spacecraft lifted off on schedule from the Baikonur Cosmodrome in Kazakhstan at 3:09 a.m. Eastern time April 28. The launch appeared to take place normally, putting the spacecraft on track to dock with the ISS about six hours later.
However, shortly after the Progress reached orbit, controllers reported that two antennas used as part of the spacecraft’s docking system failed to deploy properly. NASA initially announced that the docking would be delayed until early April 30 to give engineers time to resolve the antenna problem.
Within hours, though, it was clear the problem with the Soyuz was more serious than a faulty antenna. The spacecraft entered a roll, and Russian controllers reported problems maintaining communications with the spacecraft. NASA announced later April 28 that it had called off an attempted April 30 docking.
The U.S. Air Force’s Joint Space Operations Center, tracking the Progress, said in an April 28 statement that the spacecraft was rotating “at a rate of 360 degrees every five seconds,” or 12 RPM. The Air Force also reported tracking 44 pieces of debris in the vicinity of the Progress and its Soyuz upper stage, but could not determine from which object the debris originated.
NASA and the Russian space agency Roscosmos ruled out any attempt to dock the Progress with the ISS on April 29. “Roscosmos announced that the Progress will not be docking and will reenter the Earth’s atmosphere here some days in the future,” NASA astronaut Scott Kelly, currently on the station, said in an interview on NASA Television April 29.
The cause of the Progress failure, including whether it is a flaw with the spacecraft or its launch vehicle, is unclear. Roscosmos, in an April 29 statement, said telemetry from the Progress was interrupted 1.5 seconds before the Progress was scheduled to separate from the Soyuz upper stage. When contact was restored after separation, the spacecraft was in a spin.
With no ability to control the spacecraft, the Progress’s orbit will decay and the spacecraft will reenter some time in early May. Holger Krag, head of the European Space Agency’s Space Debris Office, said April 30 that he estimated the Progress would reenter on May 9, with a margin of error of two days.
Most of the spacecraft will burn up in the atmosphere. “However, we cannot exclude the chance that some portion of its structure, for example the heavy docking mechanism or tanks and thrusters, could survive reentry to reach the surface,” Krog said.
A typical Progress mission normally ends with the spacecraft reentering over a remote region of the South Pacific Ocean. Krog, though, said the risk to anyone on the ground from Progress debris “is extremely small.”
Constrained Supply Lines
The Progress was carrying more than 2,750 kilograms of supplies for the ISS, including fuel, water, and equipment. NASA said April 28 that none of the supplies are considered critical for operation of the station, including some spare parts and crew clothing that NASA included on the Russian spacecraft.
The loss of the Progress should not have a near-term effect on station operations. NASA said April 29 that both the Russian and American segments of the station “continue to operate normally and are adequately supplied well beyond the next planned resupply flight.”
“We have a lot of redundancy on board the space station,” Kelly said April 29. “One of the great things about this international partnership is that we do have other vehicles that can supply the space station.”
In a presentation to a NASA Advisory Council panel here April 8, NASA officials said food supplies on the ISS would reach a threshold called “reserve level” on July 24, and go to zero on Sept. 5. That assumed that the station received no more supplies beyond a SpaceX Dragon cargo mission launched to the station in April.
The other major limiting consumable is a solid waste container known by the Russian acronym KTO. Without additional cargo missions beyond the Dragon flight, KTO supplies would reach the reserve level July 20 and be exhausted on Sept. 2. Other consumables, including water, would not reach reserve levels until later in the year or early 2016.
The station is currently primarily dependent on the Progress and Dragon spacecraft to transport supplies given the retirement of Europe’s Automated Transfer Vehicle after its fifth launch last year and the infrequent use of Japan’s H-2 Transfer Vehicle (HTV). A fifth cargo vehicle, Orbital ATK’s Cygnus, has been unavailable since a Cygnus was destroyed in an Antares launch failure last October.
Current ISS manifests include three more Dragon launches in 2015: on June 19, Sept. 2, and Dec. 5. An HTV is scheduled to launch Aug. 17 and Cygnus will return to flight with a launch on a United Launch Alliance Atlas 5 on Nov. 19.
The Progress failure, though, could mean that the cargo manifests on upcoming Dragon and HTV flights could be changed to make up cargo lost on the Progress. NASA has used Dragon missions to fly scientific experiments as well as crew supplies. Those experiments accounted for more than 40 percent of the cargo, by mass, on the most recent Dragon mission.
“Teams will continue to review and suggest changes to the cargo manifest for the upcoming SpaceX mission as they do with all cargo missions,” NASA spokesman Dan Huot said April 30. “It’s still too early in the process for any changes at this time.”
Kelly, a month into a nearly one-year mission on the ISS, was not concerned about any long-term effects of the Progress failure. “I think we’re going to be in good shape.”