Russia launches third and final Angara A5 demonstration mission

by Justin Mooney

Russia has launched its third and final demonstration flight of the Angara A5 rocket on Monday, December 27. Angara is being developed and built by the Khrunichev State Research and Production Space Center and is intended to replace several existing launch vehicles.

Angara attempted to place its 2,400 kg mass simulator in a near geostationary orbit (GEO) using a new Persei upper stage. After a few hours, the Persei upper stage was to perform two burns to place the payload in a graveyard orbit, a few hundred kilometers above GEO. Russian reports, however, suggest that Persei only reached an initial low Earth parking orbit before suffering an engine failure.

Development History

To ensure Russia’s ability to conduct orbital launches without relying on the Baikonur Cosmodrome, the development of a new rocket began in 1992. The outcome was Angara, a fully Russian-designed and launched rocket, set to launch from the Plesetsk Cosmodrome.

Several companies bid for the contract to build the new rocket, and in 1994, Khrunichev State Research and Production Space Center, which also developed the Russian Proton rocket, was selected.

The initial design of Angara was to use a modified RD-170 engine on the first stage, and a liquid hydrogen and liquid oxygen powered upper stage. However, in 1997, the hydrolox upper stage had been replaced with a kerosene powered upper stage, and the RD-170 had been replaced with the brand new RD-191. Later in the year, Khrunichev received approval from the Russian government to proceed with the design.

In 2008, NPO Energomash announced that the RD-191 had completed development and hot fire testing, making it ready for manufacturing and delivery to Khrunichev. In 2009, Khrunichev took delivery of the first complete Angara first stage, and in 2010, the Director-General of Khrunichev announced that Angara was on track for its first flight test in 2013.

In 2014, 22 years after Angara’s inception, the first launch took place on July 9, as an Angara 1.2pp launched from Site 35/1 at the Plesetsk Cosmodrome. Later the same year, the first flight of the Angara A5, a heavy lift launch variant, launched from Plesetsk, carrying a MGM n°1 mass simulator into a geostationary orbit (GEO). The next Angara flight would occur six years later, with an Angara A5 launching on December 14, 2020.

Render of the Angara A5 configuration. (Credit: Mack Crawford for NSF/L2)

Stage Breakdown

Angara has several configurations that can range between 2 and 3 stages, depending on the mission requirements.

The core of any Angara rocket is the Universal Rocket Module, or the URM-1. Angara 1.2 uses a single URM-1, while an Angara A5 uses five, with four URM-1s strapped around the center core as boosters. The URM-1 is powered by a single RD-191, burning liquid oxygen and kerosene.

The second stage of Angara is the URM-2, and uses a RD-0124A, which is a derivative of the RD-0124 currently flying on the second stage of the Soyuz-2 rocket. The diameter of the URM-2 varies depending on what vehicle it flies on; Angara 1.2 is expected to use a 2.9 meter diameter URM-2 to maintain a consistent diameter throughout the vehicle, and Angara A5 uses a 3.6 meter diameter URM-2.

Angara 1.2 won’t use a third stage, and Angara A5 won’t use one while delivering payloads to low earth orbit (LEO), but will use one when delivering payloads to higher energy orbits.

Angara A5 can use either the Persei, a modified Blok DM-03 upper stage, or a new cryogenic upper stage called the KVTK. The KVTK will use a LH2/LOX powered RD-0146D, and allow the A5 to lift two additional tons to GTO, for a total of 7,500 kg.

Derived from the four chamber RD-170 designed for Energia, the RD-191 used on the first stage has been in development since 2001. The engine burns kerosene and liquid oxygen, producing 2.09 MN of thrust in a vacuum, and 1.92 MN of thrust at sea level, with a specific impulse of 337 seconds in a vacuum and 310.7 seconds at sea level. The second stage engine, the RD-0124A, consumes a mix of kerosene and liquid oxygen, produces 294.3 kN of thrust in a vacuum, and has a specific impulse of 359 seconds.

Previous Launches

The maiden flight of the Angara family was a suborbital test of the Angara 1.2pp configuration. The maiden flight was a unique configuration, used to test both the URM-1 and a 3.6 meter URM-2 ahead of Angara A5’s first flight. The test ended with an intentional impact at the Kura test range in eastern Russia.

Angara’s second flight was the maiden flight of the Angara A5, and carried a mass simulator representing a Russian geostationary communications satellite, weighing 2,400 kg. Following a complete mission success, the payload, which was not designed to separate, was placed into a graveyard orbit by two burns of the Briz-M upper stage.

Angara A5 lifts off from Plesetsk on its second demonstration mission in December 2020. (Credit: Roscosmos)

Angara’s third flight was identical to the second, with another mass simulator placed into a geostationary orbit and later placed into a graveyard orbit.

Launch Profile

Per a nominal mission, as portrayed, the mission would begin at T-0, with Angara A5 lighting its five RD-191 engines and flying east from Plesetsk.

Around 47 seconds into flight, the core URM-1 booster throttled its RD-191 to 30 percent of its rated thrust, reducing stress on the vehicle and allowing the core booster to burn longer than the outboard boosters. The four side boosters continued to burn at full thrust until three minutes and 34 seconds into flight when they shut down and separated. At this point, the core stage throttled up for another 111 seconds before it shut down and separated from the second stage.

Following stage separation, the second stage lit its RD-0124A engine and burned for 14 seconds before the payload fairings deployed. Roughly seven minutes later, the second stage shut down and separated from the Persei third stage.

After the second stage separated, Persei lit its engines to place the payload into an initial parking orbit at an altitude between 180 and 250 kilometers. Over the course of several hours, Persei was scheduled to ignite its engines multiple times to place the payload in a geostationary transfer orbit, and then later circularize the orbit at an altitude of roughly 36,000 km.

The Persei upper stage and mass simulator are encapsulated in Angara’s payload fairing. (Credit: Russian Ministry of Defense)

After the payload reached GEO, the Persei stage was to light one final time to place itself and the mass simulator into a graveyard orbit, several hundred kilometers above GEO. At this point, the stage would depressurize its tanks to avoid any potential explosion in space.

Angara’s Future

Angara has now flown three demonstration flights needed to enter operational status, but the Persei failure may prompt additional tests prior to operations. There are three flights planned for Angara in 2022 – two Angara 1.2 flights and a single Angara A5 flight.

The next flight is scheduled for January, with an Angara 1.2 for the Russian Aerospace Forces, launching a radar satellite to a sun synchronous orbit.

After that, Angara A5/Persei will launch again, scheduled for March, carrying a Russian Ekspress-AMU communications satellite to geostationary orbit.

The final launch of the year is scheduled for July, with another Angara 1.2 launching a South Korean Earth observation satellite. KOMPSAT-6, also called Arirang-6, is a synthetic aperture radar satellite, and can provide images with a resolution power between 0.5 meters and 20 meters.

(Lead photo: Angara A5 on the pad in Plestsk prior to its second demonstration mission in December 2020. Credit: Roscosmos)

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