Spektr-RG will make another launch attempt

After two delays From June 21 to July 12, the Proton rocket took off with the Spektr-RG astrophysics observatory on July 13, 2019.

Previous Chapter: Previous Launch Attempts of Spektr-RG

Third launch window for the Spektr-RG mission on July 13, 2019:

Spektr-RG Mission Launch Scenario

The launch sequence and ground track during the recall phase of the Spektr-RG launch.

The third attempt to take off the Proton-M / Block DM-03 rocket, carrying the Spektr-RG satellite, was scheduled at 15:30: 57 Moscow time (12:30 UTC, 8:30 EDT) from platform 24 on site 81 in the Baikonur cosmodrome.

Probably because the mission was targeting the L2 Lagrange point with respect to the Sun, causing the probe to escape from the initial parking orbit around the Earth at a certain geocentric position, while maintaining it at the sight of the ground stations Russian, the three-week timeframe of the launch from 21 June to 13 July shifted the takeoff time by 14 minutes to compensate for the movement of the Earth around the Sun.

According to official information published prior to the first launch attempt, on June 21, during the initial phase of the powered flight, the Proton rocket's three return stages will follow a standard flight path corresponding to an orbit with a tilt of 51. , 51 degrees to the equator. .

The separation of the first leg took place a little over two minutes after the start of the flight. The recall used was to fall in the Karaganda region of Kazakhstan. A few moments before separation, the group of four engines of the second stage resumed the powered flight, initially pulling through a trellis structure connecting two floors.

At 5 minutes and 27 seconds of flight, the four nozzles of the third-stage steering engine began to pull through the openings of the upper-stage adapter connecting it to the third floor. Four seconds later, it ensured uninterrupted acceleration of the vehicle during the ignition of the main engine of the third stage.

After about four minutes and less than six minutes of flight, the second leg separated and then descended and crashed near the border of the Tuva and Khakassia Republics of the Russian Federation.

The third floor main machine turned on a little over two seconds after separation and took over the motorized ascent. Less than 11 seconds later, the payload fairing protecting the spacecraft from aerodynamic loads in the lower atmosphere split into two halves and fell. Both fragments had to fall into the same drop zone as the second leg.

The third stage ignited its main engine RD-0213 and four thrusters up to about 9.5 minutes of flight. The four-nozzle steering motor continued to operate for an additional 12 seconds after the main engine shutdown command to fine-tune the vehicle speed to an exact setting. The payload section, including the upper stage of the DM-03 block and the Spektr-RG satellite, is separated from the third stage 9 minutes and 43 seconds after takeoff.

Upper floor maneuvers

The payload section of the Spektr-RG mission.

At the time of the separation of the third and fourth stages, the two vehicles will follow a ballistic trajectory, at a speed close to the orbital speed and will reach their apogee at an altitude of 200.4 km. With its engine stopped and most of its propellant exhausted, the third floor will then return to the atmosphere and one of the still-alive debris will fall into the Pacific Ocean, to the east. from Japan.

In the meantime, after almost six minutes of ballistic flight or 15 minutes and 44 seconds after take-off, the upper stage of the DM-03 block will have to fire its main engine. The maneuver will last 3 minutes 11 seconds, which will give the vehicle 695.93 meters per second in extra speed. It will insert the space tug and payload into a 170 km by 1,927.7 km earth orbit with an inclination of 51.49 degrees. At this altitude, it would take 1 hour 46 minutes 9 seconds for the spacecraft to complete a complete turn around the Earth. However, during the Spektr-RG mission, the battery will fly passively around the planet for only 1.3 hours before the planned start of the next propulsion phase.

The main engine of the DM-03 block should restart at T + 1 hour 37 minutes of flight and continue to fire for 9 minutes 27 seconds.

The maneuver will accelerate the vehicle by 3,957.32 meters per second and place it in an orbit of 500 km over 1,293,041 km with a 51.6 degree tilt towards the equator, effectively driving the spacecraft into the future. 39, deep space.

According to the plan, the complete process of insertion into the Earth's evacuation trajectory will take 1 hour 59 minutes 55 seconds and should be completed by separating Spektr-RG spacecraft. from its top floor 13 minutes after the completion of the second maneuver.

The observatory's separation from the scene is expected to take place within communication range of Russian ground stations tasked with controlling the Spektr-RG mission, industry sources said. The NIP-14 land station at Medvezhi Ozera, near the city of Shelkovo, in the eastern suburbs of Moscow, will serve as the main nerve center of the mission.

Approximately 1.16 hours after Spektr-RG separation, the DM-03 block stage should be routed to a safe orbit away from the spacecraft.

Spaceship Activation

The first telemetry link between the satellite and the ground is scheduled to take place at 17:38 Moscow time (10:38 am Eastern time) and begin to inform the controllers of the operations on board. A pair of solar panels aboard the Navigator service module is expected to be deployed at 19:28 Moscow time (12:28 eastern daylight time).

Between 19h38 and 19h58 (Moscow time) (12h38 – 19h58 EDT), it is planned that the mission control will activate the eROSITA telescope aboard the spacecraft.

As the spacecraft moves away from Earth, the first communication window between Spektr-RG and its ground station is scheduled to close at 21:24 Moscow time (13:24 EDT). Since the high-power transmitter on the satellite exerts considerable pressure on the operation of the observatory's thermal control system, communications with Spektr-RG will be limited to four hours a day.

After activating Spektr-RG on launch day, the satellite will spend the next three months navigating to an area 1.5 million kilometers behind the Earth from the Sun, towards one of the five so-called Lagrange points where the gravitational forces both bodies reach a balance. He will then encircle the L2 point by sweeping the sky with his eROSITA and Russian ART-XC telescopes of German design to map the Universe to X-ray light.

Next chapter: The eROSITA telescope