Artemis 1: To boldly go where four RS-25 engines have gone many times before

Artist's depiction of the SLS during launch, with four RS-25 engines, along with a pair of solid rocket boosters, providing 8.8 million pounds of thrust.

Artist’s depiction of the SLS during launch, with four RS-25 engines, along with a pair of solid rocket boosters, providing 8.8 million pounds of thrust.
picture: NASA/MSFC

Each of the four RS-25 engines currently at the base of NASA’s Space Launch System have been to space multiple times before, and each has an exciting story to tell. One of them first flew in 1998, propelling astronaut John Glenn into orbit. Soon, if all goes well, these veteran boosters will propel NASA into the age of Artemis.

NASA’s Space Launch System is the most powerful rocket ever built, capable of lifting more than 57,320 pounds (26 metric tons) of cargo and crew to the Moon. Future configurations could see the rocket lift as much as 99,208 pounds (45 metric tons). It’s an engineering marvel – at least we hope so – with its maiden flight scheduled for Saturday at 2:17 p.m. ET. But with NASA making a bold leap into the world… Artemis was And with the continuous sequence of increasingly complex missions to the lunar environment, it is important to remember that the SLS is a new rocket made from a set of old parts.

SLS on the launch pad at the Kennedy Space Center in Florida.

SLS on the launch pad at the Kennedy Space Center in Florida.
picture: NASA

The Integrated Heavy Lift Launch Vehicle is an orderly mix of previous NASA launch systems, particularly the Space Shuttle, which the United States retired in 2011. In fact, Components of the 83 Space Shuttle Missions They were assembled together to build the SLS and the Orion crew capsule. It uses the Space Shuttle’s main engine, now known as the RS-25 engine, built by Aerojet Rocketdyne, while two extended rocket boosters have also been borrowed from the shuttle. The engine that had previously maneuvered the shuttle also found its way into Orion.

as Congress Tell In 2010, NASA was to build the new rocket and crew capsule using “components derived from the Space Shuttle…utilizing current United States propulsion systems, including liquid-fuel engines, external tanks or tank-related capability and solid rocket engines…” with Keeping this in mind, and not wanting to waste good flying, proven hardware, NASA stripped the retired shuttles of their main engines and stowed them for safekeeping. This was in line with the directive to make good use of legacy hardware when creating the SLS, “to save cost and speed up schedule,” according to space agency.

There is no doubt that the RS-25 is powerful and reliable. The engines were upgraded five times over the course of the shuttle program, during which time they took part in 135 missions, blazed through more than 3,000 runs, and kept busy for a million seconds during both ground tests and flight operations. In total, NASA has amassed a stockpile of 16 RS-25D engines from the Shuttle program to support the first four SLS missions. Of these sixteen engines, only two have never been to space.

The Space Shuttle is equipped with three RS-25 engines, while the SLS has four. The four engines are powered by liquid hydrogen and liquid oxygen, and are arranged roughly in a square to ensure stability and an even distribution of force during takeoff. Each RS-25 engine can produce 2 million pounds of thrust, which, along with two solid five-section rocket boosters, will provide 8.8 million pounds of thrust at launch. During the Shuttle era, RS-25s operated at 104.5% of rated thrust (491,000 lbf. vacuum thrust), but for the SLS, these engines were modified to operate at 109% of rated thrust (512,000 lbf. vacuum thrust) NASA Says.

Space Shuttle Atlantis landing on October 23, 1989. The orbiters are equipped with three Space Shuttle Main Engines (SSMEs), now known as RS-25s.

Space ship Atlantis Landed on October 23, 1989. The orbiters are equipped with three Space Shuttle Main Engines (SSMEs), now known as RS-25s.
picture: NASA

According to NASA, “For SLS, engines will experience increased fuel inlet pressures and temperatures.” “In addition, the existing stock receives new engine control units with contemporary avionics, and new exhaust nozzle insulation for a higher heating environment.”

The current SLS configuration is known as Block 1, and includes four highly experienced RS-25 engines. For the inaugural flight of the SLS, NASA will use the E2045, E2056, E2058 and E2060 engines. In total, these four engines took part in 21 shuttle flights over three decades.

Photo of the article titled Artemis 1: To boldly go where four RS-25 engines have gone many times before

Draw: NASA

The first engine, the E2045, is the most experienced of the group, having flown 12 shuttle missions. It first flew in January 1998 during the STS-89 mission, while its last shuttle flight occurred in July 2011 during the STS-135 mission. Astronaut John Glenn tested the power of E2045 firsthand in 1998 when it flew as part of the STS-95 mission.

The second engine, the E2056, is the veteran of four shuttle flights (including the STS-114 – the first mission after Colombia disaster), while the third engine E2058 took part in six flights. The fourth engine, the E2060, is the least experienced of the group, having flown on three missions, including STS-135 – the final shuttle mission.

It’s that third engine that engineers blamed for the launch on Monday, August 29, when it failed to reach the frigid temperatures required for launch, but the team later traced the problem to a faulty sensor. As SLS chief engineer John Blevins told reporters yesterday, there was nothing wrong with the E2058, as engineers were able to confirm a “good flow” of coolant fuel through the No. 3 engine.

The four RS-25 engines used in the Block 1 SLS configuration.

The four RS-25 engines used in the Block 1 SLS configuration.
picture: Aerojet Rocketidane

For each of the 16 RS-25 engines remaining from the Shuttle era, their next flight will be their last. The SLS is a consumable missile, and the main stage is expected to collapse in the Pacific Ocean (side boosters will crash into the Atlantic Ocean). Once NASA exhausts its stockpile of RS-25D engines, the space agency will switch to RS-25E engines Currently being built by Aerojet Rocketdyne. The new engines will cost about 30% less than the previous engines and provide 111% of the rated thrust (521.000 lbs. vacuum thrust).

NASA needs the SLS for the next Artemis missions to the Moon. The heavy lift system will play a major role during Artemis 2, where a manned Orion capsule will venture to the moon and return in late 2024, as well as Artemis 3, the first manned moon landing since the Apollo era. The Artemis missions also aim to prepare NASA and its partners for the first human journey to Mars, in which the SLS is expected to play a major role.

As exciting as all of this sounds, the price may be too high. Since 2011, NASA has spent more than $50 billion in development costs for the SLS and Orion, according to Planetary Society. But to operate the SLS, NASA’s Inspector General estimates it will cost NASA upwards of $4.1 billion per launch for each of the first four Artemis missions — a price that Inspector General Paul Martin has described as “unsustainable. “

NASA, through its Artemis program, seeks a permanent and sustainable return to the Moon. However, if this happens, NASA will need to rein in the exorbitant costs.

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