Progress MS-08 arrives at ISS
The Progress MS-08 cargo ship lifted off on February 13, 2018, almost 48 hours after the original attempt was scrubbed moments before scheduled liftoff. Two days later, the re-supply mission, designated 69P, successfully delivered 1,390 kilograms of dry cargo, 890 kilograms of propellant, 430 kilograms of water and 46 kilograms of compressed air and oxygen to the International Space Station, ISS.
Progress MS-08 mission at a glance:
Preparing the Progress MS-08 mission
As of 2014, the launch of Progress MS-08 was planned for July 1, 2017. By Oct. 1, 2017, the mission was rescheduled from Feb. 9 to Feb. 13, 2018. In the December 2017 flight manifest, the launch of Progress MS-08 was set for Feb. 11, 2018, and its docking at the aft port of the Zvezda Service Module, SM, was planned during a two-orbit rendezvous scenario. On December 29, 2017, Roskosmos confirmed Feb. 11 launch date.
The assembly of the first and second booster stages for the Progress MS-08 mission was completed at Baikonur's Site 31 on Jan. 29, 2018. On the same day, the technical management met in Baikonur and cleared Progress MS-08 for irreversible operations including loading of propellant components and pressurized gases, Roskosmos said. After the completion of fueling operations, Progress MS-08 was returned to the spacecraft processing building at Site 254 on February 2. On February 5, the cargo ship was integrated with its launch vehicle adapter and the next day, specialists from RKK Energia conducted the traditional final inspection of the spacecraft, after which it was lowered in horizontal position and rolled inside its protective payload fairing.
An upper composite including the Progress MS-08 cargo ship is being integrated with booster stages of the launch vehicle on Feb. 8, 2018.
On February 7, Progress MS-08 was transferred to the vehicle assembly building at Site 112 for integration with its Soyuz-2-1a launch vehicle. The final integration of the payload section with the rocket took place on February 8. The rollout of the launch vehicle to its launch pad at Site 31 took place on Feb. 9, 2018.
As in the previous launch of the Progress MS-07 spacecraft, the Soyuz-2-1a rocket with the Progress MS-08 was rotated in its launch structure at Site 31 to match an ascent azimuth of around 60 degrees. That move aims to prepare the transition of the Soyuz-MS spacecraft from the Soyuz-FG to the Soyuz-2-1a rockets.
Ironically, the new-generation flight control system aboard Soyuz-2-1a does not require the rocket face a certain direction on the launch pad, because it can turn the vehicle to the right azimuth during the ascent. However, the Emergency Escape System, SAS, attached to the top of each spacecraft with cosmonauts onboard and designed to pull the crew capsule away from the failing rocket, is not that flexible. Its own internal guidance mechanism requires the rocket point at a certain direction with a two-degree accuracy as soon as the SAS system is activated on the launch pad before liftoff. Therefore, during the launch of the Progress MS-07 and Progress MS-08 spacecraft, engineers decided to simulate the exact flight profile that would be later employed during launches of the Soyuz MS spacecraft on the Soyuz-2-1a rocket.
The same goal of simulating the Soyuz-MS ascent also required to shift the release of the payload fairing protecting Progress MS-07 and MS-08 during the ascent through the dense atmosphere to a period of firing of the rocket's second stage (at T+183.079 seconds), rather than the third stage, as it had been done in the previous Progress launches on the Soyuz-2-1a rocket.
(The separation of the second stage was scheduled at T+287.419 seconds in flight, followed by the jettisoning of the three segments of the third stage skirt at T+296.779 seconds. All of these fragments were expected to fall in the border area between the Altai Region of Russia and Eastern Kazakhstan Region.)
Finally, the liftoff mass of the Progress MS-07 and MS-08 was to be brought up to nearly 7,430 kilograms, or almost 140 kilograms heavier than that of the previous cargo ships.
The Roskosmos State Corporation approved the new test flight profile for the Progress MS-07 mission on June 2, 2017.
Progress MS-08 was to try a two-orbit rendezvous
A Soyuz-2-1a rocket carrying Progress MS-08 cargo ship was originally scheduled to lift off on Feb. 11, 2018, at 11:58:45 Moscow Time (3:58 a.m. EST) from Pad 6 at Site 31 in Baikonur Cosmodrome.
According to mission control in Korolev, the spacecraft was to separate from the third stage of the launch vehicle at 12:07:34 Moscow Time (4:07 a.m. EST).
If launched on February 11, the mission could test a two-orbit rendezvous profile with the station, allowing the spacecraft to reach the ISS in around three and and half hours after leaving Baikonur. Under that scenario, the docking was scheduled at 15:24 Moscow Time (7:24 a.m. EST) on the day of the launch at the aft docking port of the Zvezda Service Module, SM.
Russian cosmonauts Aleksandr Misurkin and Anton Shkaplerov were to be on hand monitoring the rendezvous and docking operations from the service module and would be ready to switch to manual control in the unlikely event of problems with automated systems.
A Soyuz-2-1a rocket with Progress MS-08 seconds after launch abort on Feb. 11, 2018.
The planned launch of the Progress MS-08 spacecraft was aborted just moments before its scheduled liftoff at 11:58 Moscow Time. The Automated Engine Cutoff, AVD, command was issued indicating a technical problem with the final automated sequence. The launch vehicle remained safely on the pad. According to Roskosmos, the launch was re-scheduled for a backup opportunity on February 13, which would require a two-day rendezvous profile with the station. The situation seemingly resembled an aborted attempt to launch Progress MS-07 spacecraft on Oct. 12, 2017. During that incident, the automated launch abort, APP, command was generated due to lack of synchronization between ground-based and onboard flight control systems. At the time, it was believed that the culprit was in a flight control component, which was replaced and the problem went away. The problem was qualified as random. However, the same incident with Progress MS-08 indicates that the issue has not really been resolved until now. This time, the replacement was sent in from another production batch, even though a spare unit was available in Baikonur.
On February 12, Roskosmos announced that the new attempt to launch Progress MS-08 would be made on Feb. 13, 2018, at 11:13:33 Moscow Time (3:13 a.m. EST). According to mission control, the mission also had a backup launch time on Feb. 14, 2018, at 10:51:01 Moscow Time (2:51 a.m. EST), which would enable a docking at the ISS on Feb. 16, 2018, at 12:56 Moscow Time (4:56 a.m. EST).
Second time is a charm for Progress MS-08
After a 48-hour delay, the new attempt to launch Progress MS-08 went without a hitch and the Soyuz-2-1a rocket lifted off from the snow-covered Pad 6 at Site 31 in Baikonur on February 13, 2018, at 11:13:33.233 Moscow Time (3:13 a.m. EST). At the time, the ISS was flying over Southern Atlantic near Falkland Islands.
The orbital insertion also worked as planned and the spacecraft successfully deployed its antennas and solar arrays immediately after its separation from the third stage of the launch vehicle at 11:22:22 Moscow Time (3:22 a.m. EST).
According to the Russian mission control in Korolev, Progress MS-08 entered a close-to-planned initial orbit with following parameters:
At the time when the Progress-MS-08 reached its initial orbit, the ISS was projected to be 235.6 degrees away from the cargo ship in the so-called phasing angle. Without any additional maneuvers, the spacecraft would remain in orbit for around 30 hours or 20 revolutions around the Earth.
The docking of the Progress MS-08 spacecraft at the aft port of the Zvezda Service Module, a part of the Russian Segment of the ISS was scheduled for Feb. 15, 2018, at 13:43:30 Moscow Time (5:43 a.m. EST), mission control said.
Progress MS-08 docks at ISS
Following its successful launch, Progress MS-08 embarked on a two-day chase of the International Space Station. The flight profile called for two orbit corrections with the ship's main engine on the day of the launch, followed by a single maneuver on October 15.
The three maneuvers were scheduled to be initiated according to the following timeline and had to result in following orbital parameters:
At the time of initial rendezvous guidance for Progress MS-08 on February 15, the station was projected to be in a 403.85 by 424.47-kilometer orbit with a period of 92.6 minutes.
According to the planned timeline for the autonomous rendezvous starting at 11:20:08 Moscow Time (3:20 a.m. EST), the docking was to be preceded by a routine flyaround of the station starting at 13:20:43 Moscow Time (5:20 a.m. EST) and by a short period of station keeping 10 minutes later. However, as often the case, the rendezvous operations were smooth enough for mission control to skip the station keeping and proceed with the the final approach, which resulted with a successful docking around five minutes ahead of schedule at 13:38 Moscow Time (5:38 a.m. EST), as the two spacecraft were flying east of Philippines.
ISS configuration after the arrival of the Progress MS-08 (P69) mission.
Cargo and payloads aboard Progress MS-08
According to Roskosmos, Progress MS-08 carries 1,390 kilograms of dry cargo, 890 kilograms of propellant in the tanks of its refueling system, 430 kilograms of water in the tanks of the Rodnik system and 46 kilograms of compressed air and oxygen.
The payloads in the cargo compartment of the spacecraft include a flight version of the Ikarus remote-sensing experiment, hardware for life-support systems, containers with food, clothing, medical and hygiene supplies for crew members on the station.
On its exterior, Progress MS-08 also carries radiator panels for the Phasoperekhod experiment, which will be activated by cosmonauts from the control panel inside the ship's cargo compartment.
Official summary of cargo aboard Progress MS-08:
Completing its mission at the International Space Station, ISS, the Progress MS-08 cargo ship undocked from the aft port of the Zvezda Service Module, SM, on Aug. 23, 2018, at 05:16 Moscow Time (10:16 p.m. EDT on August 22). Three minutes later, the spacecraft fired its thrusters to enter a new orbit at a safe distance from the ISS, where it will remain for about a week for a series of tests within the Izgib ("bend") experiment.
The deorbiting of Progress MS-08 took place on Aug. 30, 2018. The beginning of the three-minute braking maneuver was scheduled at 04:23:27 Moscow Time (9:23 p.m. EDT on August 29). According to the calculations of mission control, the cargo ship reentered the dense atmosphere at 04:58 Moscow Time on August 30 (9:58 p.m. EDT on August 29) and its surviving debris impacted the remote area of the Pacific Ocean with a center point located at 41.18 South latitude and 224.29 East longitude around 05:07 Moscow Time on August 30, 2018, (10:07 p.m. EDT on August 29).
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The assembly of the first and second booster stages for the Progress MS-08 mission was completed at Baikonur's Site 31 on Jan. 29, 2018. Click to enlarge. Credit: RKK Energia
Progress MS-08 spacecraft is being prepared for its integration with launch vehicle adapter on Feb. 5, 2018. White radiator panels of the Phasoperekhod experiment are clearly visible. Click to enlarge. Credit: RKK Energia
Progress MS-08 loaded on the train for a transfer to the vehicle assembly building on Feb. 7, 2018. Click to enlarge. Credit: RKK Energia
Soyuz-2-1a rocket with Progress MS-08 spacecraft is being erected onto the launch pad on Feb. 9, 2018. Click to enlarge. Credit: RKK Energia
Progress MS-08 on the pad shortly before a launch attempt. Click to enlarge. Credit: Roskosmos
Progress MS-08 lifts off on Feb. 13, 2018. Click to enlarge. Credit: Roskosmos
A backward looking camera shows exterior of the Progress MS-08.
Progress MS-08 fires its thrusters as it approaches the ISS on Feb. 15, 2018. Credit: NASA
ISS as seen by engineering camera aboard Progress MS-08 from a distance of 224 meters during the cargo ship's final flyaround to align itself with a aft docking port on the Zvezda Service Module. Credit: NASA