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Stricken Progress cargo ship goes down

Anatoly Zak, Spaceflight Correspondent
May 8, 2015, 15:27 UTC, Updated May 8, 2015, 22:17 UTC

Sen—A nine-day drama of a stricken unmanned Russian spacecraft ended early on Friday morning with the fiery demise of the seven-ton robotic vehicle as it reentered Earth's atmosphere.

According to the Russian space agency (Roscosmos), the reentry of the Progress M-27M cargo ship took place during its 160th orbit at 05:04 Moscow Time (02:04 UTC) over the central part of the Pacific Ocean. However, it was not immediately clear how Russian space officials had been able to confirm that fact given the lack of tracking capabilities over this remote region.

Soon after Roscosmos announced the reentry, the US military confirmed the ship’s demise, but placed the event further down the orbital path of the spacecraft over the Pacific Ocean, west of the Southern tip of South America. According to that information, the reentry took place at 02:20 UTC. It should be noted that the US could actually detect the heat signature from the reentry with the help of infrared sensors onboard classified early warning satellites designed to detect ballistic missile launches.

The Progress M-27M cargo ship, loaded with more than two tons of supplies for the crew of the International Space Station (ISS), plunged into Earth's atmosphere as a result of friction with rarified air particles in the upper atmosphere. Ironically, the reentry took place not far from the region where routine Progress missions would normally end after returning from the space station loaded with trash.

The Progress M-27M spacecraft, which launched on April 28,  failed to respond to commands shortly after its separation from the third stage of the Soyuz-2-1a rocket in an initial parking orbit. The vehicle was then found tumbling uncontrollably in space and all attempts to stabilize it failed. In the following days, mission controllers in Korolev continued listening to the ship's radio signals, which kept coming thanks to an operational powered battery onboard.

Russian and U.S. orbital tracking specialists also worked tirelessly to predict the time and place for the uncontrolled reentry of the vehicle. The final public forecast from the Russian space agency said on Thursday that the Progress M-27M cargo ship would reenter Earth's atmosphere between 01:13 and 04:51 Moscow Time on Friday (from 22:13 Thursday to 01:51 Friday UTC).

It was the third prognosis issued by the agency in 48 hours, which significantly narrowed the reentry time period, but still left an ocean-wide window of uncertainty over where exactly surviving pieces of debris from the mission might fall.

According to the final advisory issued by the US military, the reentry would take place at 01:52 UTC on Friday. The forecast came after six previous estimates.

An absolute majority of the seven-ton spacecraft, including its toxic propellant, is likely to have been incinerated by plasma of the hypersonic reentry, however some small components made of heat-resistant materials could have made it all the way to the surface, experts say.

The ill-fated mission leaves a lot of uncertainty in its wake. The investigation into the root cause of the Progress M-27M accident reportedly focuses on the third stage of the Soyuz-2-1a rocket, which delivered the spacecraft.

A cloud of 44 pieces of trackable debris emanating from the launch hinted at a possible explosion of the stage, however what caused the blast is still unclear. The mystery will have to be resolved before many Soyuz rockets in the Russian flight manifest can proceed to the launch pad.

On May 7, the Interfax news agency reported that the Soyuz TMA-17M spacecraft—slated to launch with three crew to the International Space Station on May 26—would be delayed for one and a half to two months.

According to the TASS news agency, the return of three members of the 43rd long-duration expedition onobard the ISS would also be postponed from May 14 until June. It will be followed by another attempt to deliver supplies to the station with Progress M-28M at the end off June or in early July.

Unofficial sources also say that a Soyuz-2-1a rocket, which was scheduled to launch a spy satellite from Russia's military launch site in Plesetsk on May 15, will also be grounded for now.