Progress MS-08 cargo ship launches on 2-day trek to ISS

Progress MS-08 is launched by a Soyuz 2.1a rocket. Credit: Roscosmos

After a two-day launch delay, Progress MS-08, an autonomous Russian cargo spacecraft, is on its way to the International Space Station.

Liftoff took place atop a Soyuz 2.1a rocket occurred at 3:13 a.m. EST (08:13 GMT) Feb. 13, 2018, from launch pad 31 from the Baikonur Cosmodrome in Kazakhstan. The spacecraft is carrying some 1,390 kilograms of dry cargo, 890 kilograms fuel, and 420 kilograms of water, as well as 46 kilograms of oxygen to the outpost.

Progress MS-08 will spend 34 orbits catching up with the ISS before docking to the aft port of the Zvezda service module at the rear of the orbiting laboratory. Docking is anticipated to occur around 5:43 a.m. EST (10:43 GMT) Feb. 15, 2018.

The mission was supposed to occur on Feb. 11. However, the countdown was scrubbed less than a minute before the flight was scheduled to get underway. Everything during the attempt appeared to proceed smoothly up to the abort. At around 35 seconds prior to the planned liftoff time, the first of two umbilical towers were retracted as planned. A second, smaller tower was supposed to retract around the 12-second mark to trigger the launch ignition sequence. This did not happen, and the engines did not ignite.

Roscosmos has not disclosed the cause of the scrub. However, a similar abort occurred on the previous Progress spacecraft launch in October 2017.

Also just like in October, this Progress was to test out a new fast-track to the outpost. Rather than a 34-orbit, two-day rendezvous to the ISS, or even the newer four-orbit, six-hour profile, Progress MS-08 was to try a two-orbit profile to arrive at the outpost in about 3.5 hours.

This short rendezvous profile requires precisely-aligned orbits and the scrub meant the attempt had to be cancelled.

Progress MS-08 was launched by the 46.1-meter tall, 2.95-meter wide Soyuz 2.1a rocket. The medium-lift booster has the capacity to send 7.8 metric tons to low-Earth orbit.

Soyuz 2.1a sports four liquid-fueled strap-on boosters each with a single RD-107A engine. They surround the 27.8-meter tall core stage, which is powered by an RD-108A engine. 

The strap-on boosters consumed their fuel and fell away just under two minutes into the flight. Next, the payload fairing protecting the Progress MS-08 spacecraft jettisoned just over three minutes after liftoff as it was high enough to no longer be needed. Nearly five minutes into flight, the core stage finished its job and also fell away.

A 6.74-meter tall upper stage, powered by an RD-0110 engine, finished the job of placing Progress MS-08 into orbit less than nine minutes after leaving Kazakhstan.

Once Progress separated from the upper stage, its various antennas and twin solar panels deployed. The freighter then began its two-day chase of the ISS.

The vehicle will spend about six months attached to the ISS. Over that time, the outpost’s crew will unload the cargo from the spacecraft before reloading it with trash and unneeded equipment. Once Progress MS-08 undocks in late-August, it will be commanded to deorbit and reenter Earth’s atmosphere to burn up.

NOTE: While this article was written by Derek Richardson, it was originally published at SpaceFlight Insider. Feel free to head over there to read all the stuff they write about!