Featured image credit: ROSCOSMOS
Lift Off Time
|October 28, 2021 – 00:00 UTC | 03:00 MSK|
|Progress MS-18 (79P), a resupply mission to the International Space Station (ISS)|
|Launch Complex 31/6, Baikonur Cosmodrome, Kazakhstan|
|~2,550 kg (5,600 lb) of cargo|
Where is the spacecraft going?
|It will rendezvous with the ISS, ~400 km low-Earth orbit (LEO) at a 51.65° inclination|
Will they be attempting to recover the first stage?
|No, Soyuz is not capable of recovery|
Where will the first stage land?
|The boosters will crash into the steppes of Kazakhstan|
Will they be attempting to recover the fairings?
|No, Soyuz is not capable of recovery|
Are these fairings new?
How’s the weather looking?
This will be the:
|– 6th uncrewed mission to the ISS of 2021|
– 18th launch of a Progress MS spacecraft
– 56th mission of Soyuz 2.1a rocket
– 79th cargo delivery to the ISS
– 170th flight of a Progress spacecraft
– 105th orbital launch attempt of 2021
Where to watch
What does all this mean?
Progress MS-18 (79P) is a cargo resupply mission that will be heading to the International Space Station (ISS). ROSCOSMOS will launch it using an uncrewed Progress MS spacecraft atop a Soyuz 2.1a launch vehicle. The rocket will lift off from Launch Complex 31/6, at the Baikonur Cosmodrome, in Kazakhstan. This mission will mark the 18th flight of the Progress MS capsule and the 79th cargo delivery to the space station.
Progress MS-18 (79P)
Progress MS-18 will carry propellant and pressurized gases with a total mass of 603 kg, as well as food, 420 liters of water for the Rodnik system, biological experiments, and other cargo and equipment with a total mass of 1,490 kg. Overall, this mission will bring approximately 2,550 kg of cargo to support the Expedition 66 at the ISS.
Progress MS-18 Mission Profile
Progress MS will separate from the third stage of the Soyuz 2.1a at ~9 min after launch. The capsule is scheduled to arrive at the ISS two days later, on Saturday, October 30, at 01:34 UTC (04:34 MSK). The Progress MS capsule will autonomously dock to the aft port of the Zvezda Service Module.
On this mission, ROSCOSMOS will test some elements of the fast rendezvous technique that in the future will allow to reach the ISS in just one orbit or about two hours. It is reported that first tests were performed on the Progress MS-17 mission that launched on June 30, 2021. There, the spacecraft entered the coelliptic orbit required for this one-orbit scheme and stayed there for about 50 min. The Progress MS-18 spacecraft will proceed with the following maneuvers: after first two burns, it will enter one coelliptic orbit, and then, it will shift to another one; this will help to understand “the accuracy the coelliptic orbit is formed with and the velocity of its decay.” If everything goes as planned, it will be possible to introduce the one-orbit rendezvous scheme for the Progress MS-20 mission.
|– 00:00:15||Engine start sequence|
|+ 00:01:58||First stage separation|
|+ 00:03:03||Fairing jettison|
|+ 00:04:47||Second stage separation|
|+ 00:04:57||Tail section separation|
|+ 00:08:45||Third stage main engine cutoff|
|+ 00:08:49||Progress MS separation|
What is Soyuz 2.1a?
ROSCOSMOS’s Soyuz is a multi-use medium-lift launch vehicle that was introduced in far 1966 and since then has been the workhorse of the Soviet/Russian space program. It is capable to launch civilian and military satellites, as well as cargo and crewed missions to the ISS. Over the decades, several variants of the Soyuz rocket have been developed. Soyuz 2.1a is one of its latest iterations that belongs to the Soyuz-2 rocket family.
The rocket consists of three stages, all of them are expendable. When launching to the ISS, Soyuz-2 can be flown with either a Progress capsule or a Soyuz spacecraft. On the Progress MS-18 mission, the Progress MS module will be used to deliver cargo to the ISS.
Soyuz 2.1a is about 46.3 meters (152 ft) in height and 2.95 meters (9 feet) in diameter. The vehicle’s total lift-off mass is approximately 312,000 kg (688,000 lb). The rocket’s payload lift capacity to low-Earth orbit (LEO) is between 6,600 and 7,400 kg depending on the launch site.
This mission will be dedicated to the 800th anniversary of Nizhny Novgorod (Russia’s fifth largest city by population) in 2021 and the cooperation agreement between the government of this city and ROSCOSMOS. This is why the Soyuz 2.1 rocket is decorated with patterns of the Khokhloma painting that originated in Nizhny Novgorod and was first mentioned in 1659.
|First Stage||Second Stage||Third Stage|
|Total Thrust||840 kN (188,720 lbf), |
1,020 kN (229,290 lbf),
|792 kN (178,140 lbf),|
922 kN (207,240 lbf),
|298 kN (67,000 lbf),|
|Specific Impulse (ISP)||263 s, sea level|
320 s, vacuum
|258 s, sea level|
321 s, vacuum
|326 s, vacuum|
The first stage of the Soyuz 2.1a rocket is composed of 4 side boosters that are powered by RD-107A engines. Each one of the boosters has a conical shape and a dry weight of 3,784 kg. It is approximately 19.6 meters in length, with a diameter of 2.7 meters. Each side booster has two vernier thrusters that are used for flight control.
The RD-107A engine runs on rocket-grade kerosene (RP-1) and liquid oxygen (LOx). The propellants are stored in the pressurized aluminum alloy tanks, the kerosine tank is located in the cylindrical part of the booster, and the LOx one is in the conical section. Each one of those engines has 4 combustion chambers and together they are capable of producing a thrust of 840 kN at sea level and 1,020 kN in a vacuum.
Perhaps, the most spectacular moment of the Soyuz-2 rocket’s launch is the separation of the first stage. It happens approximately 2 minutes after the launch. The boosters perform a pattern, known as the “Korolev cross” (named after Sergei Korolev, a very important figure of the USSR space program and history).
Second and Third Stages
The center core stage is powered by a single RD-108A engine, and the upper stage is fitted with a single RD-0110 engine. Both of these engines run on rocket-grade kerosene and LOx and have 4 combustion chambers. The second stage is 27.10 meters long, with a diameter of 2.95 meters, and a dry mass of 6,545 kg. It has 4 vernier thrusters for three-axis flight control.
The third stage of a Soyuz-2 rocket has a height of 6.7 meters, a diameter of 2.7 meters, and a dry mass of 2,355 kg. One interesting thing about the engine on this stage is that it starts its ignition sequence prior to stage separation. This process is called “hot fire staging”.
Progress MS Spacecraft
The Progress module is a space “truck” for delivering cargo to the ISS. Its design is largely derived from the Soyuz spacecraft that serves for the transportation of astronauts to the ISS. The Progress capsule is 7.9 meters in length and 2.7 meters in diameter. It consists of three parts: a pressurized cargo module, a propellant compartment, and a rear service module (like the Soyuz spacecraft).
Unlike Cargo Dragon 2, it is not designed to bring cargo back to Earth. This is because the three modules on Progress are not capable to split before re-entry. Therefore, after unloading the cargo, the crew progressively fills it only with trash. At the end of its mission, the spaceship separates from the ISS, performs a deorbit burn, and entirely burns up upon re-entry in Earth’s atmosphere.
The MS series is the latest modernized variation of the Progress spacecraft that began flying in December 2015. Among the introduced upgrades are improved orbital debris shielding, a new flight-control and navigation systems, as well as a new external compartment that can be used for satellite deployment.
Kurs-NA Automatic Docking System
Like the Soyuz spacecraft, Progress MS is equipped with a Kurs-NA automatic docking system that was first tested on the Progress M-15M mission in July 2012. Compared to its ancestor, Kurs-A, the new system has only one AO-753A rendezvous antenna. Kurs-A had five (two 2AO-VKA and three AKR-VKA) of them. This antenna broadcasts radar pulses that are needed to determine the altitude and relative position of the spacecraft to the ISS. Moreover, Kurs-NA uses less power than Kurs-A.
In addition, the Progress MS spacecraft can be docked to the ISS manually by the docking system called the Tele-Robotically Operated Rendevous unit (TORU). This manual system serves as a backup to Kurs-NA in emergency situations and is located inside the Zvezda service module. On the Progress MS-16 mission, the control of the capsule had to be switched over to the TORU due to a signal strength issue of the Kurs system.