Proton launches Ekspress duo after a 24-hour delay
During its first and only mission of 2020, Russia's Proton rocket successfully delivered the Ekspress-80 and Ekspress-103 communications satellites for the Russian state-owned operator Kosmicheskaya Svyaz. The vehicle lifted off as scheduled at 00:25:19 Moscow Time on July 31 (5:25 p.m. EDT, 21:25 UTC on July 30). The launch was postponed for 24 hours due to a need for additional checks, Roskosmos said.
Proton launch with Ekspress-80/-103 satellites at a glance:
Ekspress-80 and Ekspress-103 satellites were built by ISS Reshetnev in Zheleznogorsk based on its Ekspress-1000N standard platform. The satellites were ordered by Russia's state-owned operator Kosmicheskaya Svyaz. The satellites' transponder payload was sub-contracted to the Italian division of Thales Alenia Space, which previously worked with ISS Reshetnev on multiple projects. As reflected in their designations, Ekspress-80 was intended for deployment in the geostationary orbit at the orbital position 80 degrees East longitude and Ekspress-103 was to be originally stationed at 103 degrees East longitude, before moving to 96.5 East.
According to Roskosmos, both satellites had an operational warranty of 15 years, but had "technical potential" for 17 years of operation. They were designed to provide fixed and mobile communications in C-, Ku- and L-band, digital broadcasting and Internet services across Russia and the former Soviet republics.
The satellites were equipped with payloads designed for the transmission of digital modulation signals received by the spacecraft in continuous mode and in the TDMA regime with a single-signal and a multi-signal mode, Roskosmos said.
Known specifications of the Ekspress-80 and Ekspress-103:
Preparations for launch
The launch of the Ekspress-80/-103 tandem was originally promised in 2018, but during 2016, the mission slipped to the fourth quarter of 2019. On January 31, 2018, Roskosmos announced that the payload structure module for Ekspress-80 had been delivered from ISS Reshetnev to Rome and was undergoing acceptance checks at Thales Alenia Space Italy by a team of engineers including specialists from Reshetnev. In Italy, Thales integrated its payload with the module.
In the meantime, by 2019, the launch was delayed until 2020 and, and by the end of 2019, it was planned for March 30, 2020. According to GKNPTs Khrunichev, the Proton-M launch vehicle and the payload fairing for the mission were shipped from the assembly factory in Moscow to Baikonur during the night from December 5 to December 6, 2019. The train arrived at Baikonur on December 15.
In January 2020, ISS Reshetnev announced that the mission was planned for April 2020, but by February, the launch was set for March 31. On February 20, 2020, Roskosmos announced that Ekspress-80 and -103 had been delivered to Baikonur.
On March 10, 2020, Roskosmos quoted Director General at GKNPTs Khrunichev Aleksei Varochko as saying that quality control procedures uncovered a "mismatch" in one of the checked parameters in the components of a Proton rocket. To ensure reliability, the decision was made to replace a series of components, including those on the Proton-M launch vehicle intended for the Ekspress mission at Baikonur Cosmodrome. According to industry sources, Varochko referred to a series of bolts which keep together components of the rocket and were found to be defective.
As a result, the launch of the Ekspress satellite was expected to be re-scheduled for the end of May 2020, Roskosmos said. However, early in April, the rocket for the mission, along with at least one more Proton vehicle, had to be shipped back to Moscow because the repairs had to be made in factory conditions, RIA Novosti reported, quoting an industry source. As a result, the mission had to be postponed until the end of July 2020.
On June 5, 2020, the Proton rocket and the Briz-M upper stage for the Ekspress-80/-103 mission were shipped to Baikonur, Roskosmos announced. Before its return to Moscow for repairs, that particular Proton vehicle was slated for the launch of the MLM Nauka module. Because this rocket had the smallest number of defective bolts to be replaced, it was repaired first, while the Proton originally assigned to launch the Ekspress-80/-103 pair was still at Baikonur, waiting its turn to be returned to Moscow. The train carrying the repaired Proton-M rocket and its Briz-M upper stage for the Ekspress mission arrived at the processing complex in Baikonur on June 15, 2020.
In early July 2020, ISS Reshetnev announced the resumption of the Ekspress-80/-103 launch campaign. The company's specialists were expected to charge batteries aboard the spacecraft and then integrate the pair with its upper stage and the launch vehicle, ISS Reshetnev said.
On July 21, 2020, specialists completed the assembly of the payload section for the mission, stacking the spacecraft duo on top of the Briz-M upper stage inside the processing building at Site 92A-50. According to Roskosmos, electric and pneumatic tests confirmed the readiness of the payload section, clearing the way for its integration with the launch vehicle which was expected to last for three days and to be followed by the fueling of low-pressure tanks aboard the Briz-M stage.
The fully assembled rocket with Ekspress-80 and -103 satellites was rolled out to the launch pad No. 39 at Site 200 on July 26, 2020, with the planned liftoff on July 30, at 00:27:42 Moscow Time (21:27 UTC, 5:27 p.m. EDT on July 29). However before the end of the work day in Moscow on July 29, Roskosmos announced that the State Commission postponed the launch due to the need for additional system checks.
The new launch attempt was set for 00:25:19 Moscow Time on July 31, 2020 (5:25 p.m. EDT, 21:25 UTC on July 30), Roskosmos said.
According to RIA Novosti, quoting an industry source, there was a problem in the flight control system of the Briz-M stage. The TASS reported that the problem was in the avionics unit responsible for the operation of the engine aboard Briz-M. The component was built by OKB Mars in Moscow, which supplies flight control systems for the Russian space industry. The State Commission reconvened around 16:00 Moscow Time on July 30 and cleared the vehicle for liftoff.
A Proton-M/Briz-M rocket carrying the Ekspress-80 and Ekspress-103 communications satellites lifted off from Pad 39 at Site 200 in Baikonur Cosmodrome on July 31, 2020, at 00:25:19 Moscow Time (21:25 UTC, 5:25 p.m. EDT on July 30).
After several seconds in vertical ascent, the Proton headed east along a standard ascent trajectory, which enabled it to reach an orbital inclination of around 51 degrees toward the Equator. The firing of the first, second and third stages of the rocket were designed to insert the payload section, including the Briz-M stage and the two satellites into a suborbital trajectory, just short of orbital velocity. Nearly 1.5 minute after the separation from the third stage, Briz-M was slated to fire its engine in order to reach an initial parking orbit.
Briz-M should then perform a series of five maneuvers to climb to a super-synchronous transfer orbit with an apogee (the highest point) of 54,900 kilometers and perigee 16,600 kilometers.
Around an hour after launch, Roskosmos confirmed that the first firing had been completed as planned.
By climbing to an altitude exceeding 36,000 kilometers, where the satellites will ultimately operate, the Briz-M will be less bound by our planet's gravitational pull. As a result, the space tug will be able to carry a heavier payload during the energy hungry maneuver which will tilt the orbital plane of the satellites from the latitude of the Baikonur Cosmodrome in Kazakhstan closer to the equatorial plane.
During its ride to orbit, the Ekspress-80 will be located on top of the two-satellite stack and it will separate first from Ekspress-103, 17 hours 59 minutes after the liftoff from Baikonur. It will be followed by Ekspress-103, separating from the Briz-M stage 18 hours and 16 minutes after launch. This is believed to be the longest orbital ascent profile in the history of Proton missions.
Around 18:30 Moscow Time on July 31, 2020, Roskosmos confirmed that Ekspress-80 had separated from Briz-M and had been under control, delivering good telemetry. The successful release and the contact with the Ekspress-103 satellite was confirmed within the following half an hour.
Timeline of the Proton launch with Ekspress-80 and -103 satellites on July 31, 2020:
Following their separation from the launch vehicle in the super-synchronous transfer orbit, SSTO, both satellites were expected to use their own electric propulsion system, consisting of two SPD-100V thrusters, to enter a proper circular geostationary orbit, GSO, around 36,000 kilometers from the Earth's surface. The thrust of two engines on each spacecraft was aligned with the -X axis on the spacecraft. The transition to the GSO was designed to coincide with the transfer of the satellites to their operational position in the geostationary orbit.
The time of transfer to their respective operational orbits should not exceeded 152 days for Ekspress-80 and 160 days for Ekspress-103, Roskosmos said. According to Kosmicheskaya Svyaz, the satellites would be ready for operational use in January or February 2021.
In the middle of January 2021, ISS Reshetnev announced that Ekspress-80 had reached a working point and had been undergoing payload tests. At the same time, Ekspress-103 had reached its target orbit and had been placed into an intermediate position at 103 East longitude for tests, the company said.
At the end of February 2021, Ekspress-103 began moving westward and was expected to arrive at the final operational position at 96.5 degrees East longitude by March 8, 2021.
Ekspress satellite is being prepared for testing of its radio system in the anechoic chamber. Click to enlarge. Credit: Roskosmos
Ekspress-80 satellite is being installed on the Ekspress-103, which is in turn sits on the Briz-M upper stage during the launch campaign in Baikonur. Click to enlarge. Credit: Roskosmos
Proton with Ekspress-80 and -103 satellites arrives at launch pad on July 26, 2020. Click to enlarge. Credit: Roskosmos
Access gantry is being retracted from the Proton rocket shortly before its liftoff with Ekspress-80, -103 satellites. Click to enlarge. Credit: Roskosmos
Click to enlarge. Credit: Roskosmos
Click to enlarge. Credit: Roskosmos
Proton with Ekspress-80 and -103 satellites lifts off on July 31, 2020. Click to enlarge. Credit: Roskosmos