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payload

The payload section of the Soyuz rocket with 34 OneWeb satellites. Credit: Arianespace


logo

OneWeb dedicated its third launch to late Aleksei Leonov who made history 55 years earlier with the world's first spacewalk. Credit: OneWeb


cluster

Soyuz-2-1b rocket with 34 OneWeb satellites is being erected on the launch pad on February 3, 2020. Click to enlarge. Credit: Roskosmos


cluster

Soyuz rocket is being fueled shortly before planned liftoff on March 21, 2020. Click to enlarge. Credit: Roskosmos


cluster

Click to enlarge. Credit: Roskosmos


cluster

Click to enlarge. Credit: Roskosmos


cluster

Soyuz lifts off with 34 OneWeb satellites on March 21, 2020. Click to enlarge. Credit: Roskosmos


cluster

Click to enlarge. Credit: Roskosmos


cluster

Rendering of Fregat upper stage with 34 OneWeb satellites during a passive flight in the initial orbit. Click to enlarge. Credit: Arianespace


 

 

 

 

Soyuz launches third OneWeb cluster

In the midst of the coronavirus pandemic and backdropped by a report about possible impending bankruptcy of the OneWeb company, Russian specialists in Baikonur, Kazakhstan, orbited the third cluster of satellites for the OneWeb Internet constellation. The launch of the Soyuz-2-1b rocket with 34 satellites took place as scheduled on March 21, 2020, at 20:06 Moscow Time (1:06 p.m. EDT) from Site 31.


launch

The third Soyuz mission with OneWeb satellites at a glance:

Mission and spacecraft designation
OneWeb, ST28, Satellites No. 41 - No. 74
Launch vehicle
Soyuz 2-1b No. 15000-049 /Fregat-M No. 123-02
Payload fairing
81KS. 1000-0 No. N15000-038
Launch site
Launch date and time
2020 March 21, 20:06:58.196 Moscow Time (actual), 20:06:58 (planned)
Payload mass
5,689 kilograms
Spacecraft mass
34 satellites 147.5 kilograms each, total 5,015 kilograms
Target orbit
Altitude: ~450 kilometers, inclination 87.4 degrees*

*Satellites will use their own propulsion system to enter a 1,200-kilometer operational orbit

 

Preparing the third OneWeb mission

If successful, the third launch of the OneWeb project will increase the low-orbital Internet constellation from 40 to 74 satellites. The European Arianespace consortium, which was contracted to perform the delivery, designated the mission ST28 to denote the 28th commercial launch conducted by the company and its Starsem affiliate from Baikonur.

At the beginning of 2020, the ST28 mission was expected to lift off on March 18, but it was later shifted to March 21, due to logistical delays associated with the delivery of OneWeb satellites from their assembly facility in the US state of Florida. The batch of 34 satellites departed for Baikonur aboard an An-124 transport aircraft on February 24, 2020.

The launch vehicle was rolled out to the launch pad on the morning of March 18, 2020. The final preparations on the pad coincided with strict measures in Baikonur, in the attempt to limit the spread of the coronavirus. Moreover, on March 19, Bloomberg.com reported that OneWeb was considering a bankruptcy filing.

oneweb

Soyuz-2-1b rocket with 34 OneWeb satellites is being erected on the launch pad on February 3, 2020.


According to Arianespace, its OneWeb launch campaign in Baikonur includes preparation of the satellites inside the Payload Processing Facility at Site 112, followed by fueling and mounting to the dispenser inside the Hazardous Processing Facility, HPF. The combination of the satellites and the dispenser is then mated to the Fregat upper stage, and together they are encapsulated under the fairing, forming the upper composite. The subsequent launch campaign typically follows this timeline:

L-7 days (or in the night from L-7 to L-6):

  • Upper composite (satellites + dispenser + Fregat with intermediate bay + fairing) is transferred to the launch vehicle assembly facility (“MIK-40”) at Site 31 near launch pad No. 6;

L-6 to L-4 days:

  • The Upper Composite is mated to the launch vehicle’s third stage, completing the full assembly of the launcher, enabling connections to be verified;

L-4 days:

  • The Transfer Readiness Review ensures the Soyuz launch vehicle and its payload are ready for final launch pad activity and for the launch itself;

L-3 days:

  • The fully assembled launch vehicle is transferred to the pad and erected in the vertical position. Check out of the launch vehicle’s three lower stages takes place;

L-2 days:

  • Countdown rehearsal for the customer’s spacecraft, along with the Fregat upper stage and the launcher’s three stages, as well as verification of the guidance system;

L-10 hours:

  • Final countdown begins. System checks begin on the Soyuz launcher’s three stages;

L-5 hours 10 min:

  • System checks begin on the Fregat upper stage;

L-4 hours 20 minutes:

  • Launch vehicle fueling authorization review;

L-4 hours:

  • Launch vehicle fueling begins;

L-30 minutes:

  • Opening of service platform;

L-2 minutes 25 seconds:

  • Pressurization of propellant tanks;

L-40 seconds:

  • Transfer to on-board power supply;

L-20 seconds:

  • Ignition of booster and core engines at intermediate thrust level;

L-0:

  • Lift-off!

Planned countdown milestones for the ST28 mission, according to Arianespace:

PRE-LAUNCH EVENTS
Time (h:min:sec)
Beginning of the meeting for launcher fueling authorization (BTR)
-05:00:00
Beginning of launch vehicle fueling with propellant components
-04:30:00
Completion of launch vehicle fueling
-01:35:00
Test bars at 1 kHz tone
-00:30:00
"Key-to-launch" command (beginning of Soyuz synchronized sequence)
-00:05:09
Fregat transfer to onboard power supply
-00:05:00
Upper Composite umbilical drop off command
-00:02:25
Ground-board power transfer
-00:00:40
Lower stage mast retraction
-00:00:28
Ignition
-00:00:19
Preliminary thrust level
-00:00:14
Liftoff
00:00:00

 

Initial launch profile

insertion

A Soyuz-2-1b rocket carrying a cluster of 34 OneWeb satellites lifted off from Site 31 in Baikonur as scheduled on March 21, 2020, at 20:06:58.196 Moscow Time (1:06 p.m. EDT). The ascent profile of the mission followed the same timeline and flight parameters employed in the previous OneWeb launch from Baikonur.

After a few seconds of vertical ascent, the launch vehicle began heading northward, across Kazakhstan and Russia to align its ascent trajectory with a near-polar orbit inclined 87.4 degrees toward the plane of the Equator.

The four boosters of the first stage separated 1 minute and 58 seconds after liftoff, but the core booster of the second stage continued firing until 4 minutes and 48 seconds into the flight. It separated moments after the ignition of the third stage. Two seconds later, the payload fairing, which protected the payload in the dense atmosphere, split in the two fragments and fell off.

The third stage fired until 9 minutes and 23 seconds into the flight, releasing the Fregat upper stage and its cargo on a ballistic trajectory with a highest point 191 kilometers above the Earth's surface, but just short of orbital velocity. It allowed the third stage to reenter and fall into a projected area of the Arctic Ocean, north of the Canadian coast.

Planned upper stage maneuvers

scenario

Exactly one minute after the separation from the third stage, the Fregat fired its main engine for 4 minutes and 11 seconds to enter a transfer elliptical (egg-shaped) orbit with the lowest point (perigee) 140 kilometers above the Earth and the highest point (apogee) 425 kilometers above's the Earth's surface, which is near the target altitude for the release of OneWeb satellites.

Shortly after the planned maneuver, Head of Roskosmos Dmitry Rogozin announced that the first firing of the Fregat's engine had gone as scheduled.

After its first maneuver, the Fregat climbed passively for nearly an hour. Upon reaching the apogee of the transfer trajectory, Fregat re-ignited its engine for 34 seconds to make its orbit circular at an altitude of around 450 kilometers.

The first pair of OneWeb satellites was released in opposite directions from their dispenser 1 hour 11 minutes and 40 seconds after launch.

In the meantime, the space tug was to re-appeared within the range of Russian ground stations at 21:40 Moscow Time (or 1 hour 34 minutes after launch), according to Rogozin.

In the following 15 minutes after the release of the first pair of satellites, Fregat made a 15-second burn with its small attitude control thrusters to get in position for another release around three minutes later, this time, of four satellites. The Fregat was then programmd to repeat its thruster firing and release routine seven more times, evenly distributing the quartets of satellites along their orbit. The final four of 34 passengers were off their space tug 3 hours and 45 minutes after their liftoff from Baikonur.

Around 1 hour and 20 minutes after the release of the final quartet, the Fregat was programmed to initiate a braking maneuver with its main engine which was designed to push the stage on a disposal orbit, resulting in its quick destruction in the upper atmosphere nearly six hours after launch. In total, Fregat performed 11 active maneuvers: three with the main engine and eight firings of the SOZ attitude control thrusters.

OneWeb confirmed signal acquisition from all 34 satellites delivered during the mission. Following their release, the satellites were expected to maneuver to their operational positions 1,200 kilometers above the Earth's surface, using onboard electric thrusters.

The ST28 mission timeline on March 21, 2020:

Event
Scheduled elapsed time
Liftoff
0
Stage I separation
1 minutes 58 seconds
Stage II separation
4 minutes 48 seconds
Payload fairing separation
4 minutes 50 seconds
Stage III separation
9 minutes 23 seconds
Fregat main engine firing 1 begins
10 minutes 23 seconds
Fregat main engine firing 1 ends
14 minutes 34 seconds
Fregat main engine firing 2 begins
1 hour 06 minutes 45 seconds
Fregat main engine firing 2 ends
1 hour 07 minutes 19 seconds
Separation 1 of first two OneWeb satellites
1 hour 11 minutes 40 seconds
Fregat attitude control system firing 1 begins
1 hour 27 minutes 30 seconds
Fregat attitude control system firing 2 ends
1 hour 27 minutes 45 seconds
Separation 2 of four OneWeb satellites
1 hour 30 minutes 50 seconds
Fregat attitude control system firing 2 begins
1 hour 46 minutes 40 seconds
Fregat attitude control system firing 2 ends
1 hour 46 minutes 54 seconds
Separation 3 of four OneWeb satellites
1 hour 50 minutes 00 seconds
Fregat attitude control system firing 3 begins
2 hours 05 minutes 50 seconds
Fregat attitude control system firing 3 ends
2 hours 06 minutes 03 seconds
Separation 4 of four OneWeb satellites
2 hours 09 minutes 10 seconds
Fregat attitude control system firing 4 begins
2 hours 25 minutes 00 seconds
Fregat attitude control system firing 4 ends
2 hours 25 minutes 11 seconds
Separation 5 of four OneWeb satellites
2 hours 28 minutes 20 seconds
Fregat attitude control system firing 5 begins
2 hours 44 minutes 10 seconds
Fregat attitude control system firing 5 ends
2 hours 44 minutes 20 seconds
Separation 6 of four OneWeb satellites
2 hours 47 minutes 30 seconds
Fregat attitude control system firing 6 begins
3 hours 03 minutes 20 seconds
Fregat attitude control system firing 6 ends
3 hours 03 minutes 29 seconds
Separation 7 of four OneWeb satellites
3 hours 06 minutes 40 seconds
Fregat attitude control system firing 7 begins
3 hours 22 minutes 30 seconds
Fregat attitude control system firing 7 ends
3 hours 22 minutes 37 seconds
Separation 8 of four OneWeb satellites
3 hours 25 minutes 50 seconds
Fregat attitude control system firing 8 begins
3 hours 41 minutes 40 seconds
Fregat attitude control system firing 8 ends
3 hours 41 minutes 46 seconds
Separation 9 of four OneWeb satellites
3 hours 45 minutes 00 seconds
Fregat main engine firing 3 begins for deorbiting
5 hours 05 minutes 55 seconds
Fregat main engine firing 3 ends for deorbiting
5 hours 06 minutes 41 seconds
Mission end
5 hours 52 minutes 20 seconds

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Page author: Anatoly Zak; Last update: March 22, 2020

Page editor: Alain Chabot; Last edit: March 20, 2020

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