Terran 1

Blog Credit: Trupti Thakur

Image Courtesy: Google

Terran 1

Terran 1 was an expendable two-stage small-lift launch vehicle developed by Relativity Space. Development began in 2017 and the rocket was retired in 2023.  Most structures and components in the vehicle were manufactured with 3D printing processes. The maximum payload was expected to be 1,250 kg (2,760 lb) to 185 km (115 mi) low Earth orbit (LEO). Relativity’s advertised launch price was $12 million USD per Terran 1 mission.

Terran 1’s first and only launch took place on March 23, 2023, from Cape Canaveral. It passed max q and reached space but did not achieve orbit due to a failure of the second stage. Following the failed launch, Relativity retired the rocket in favor of developing the much larger, reusable Terran R vehicle.

 

On March 8, Relativity Space, a startup company based in California, made history with the launch of Terran 1, the world’s first 3D-printed rocket. The launch is part of the “Good Luck, Have Fun” (GLHF) mission. Terran 1 will be the largest 3D-printed object to attempt an orbital flight, weighing 9,280 kilograms and standing 110 feet tall and 7.5 feet wide. 85% of the rocket was manufactured using 3D-printing technology.

 

About Terran 1

It is a two-stage satellite, which means the fuel burns in two different stages to give the required escape velocity to the satellite. Terran 1 is an expendable launch system, which means can be launched only once. Satellites like Falcon 9 are reusable and can be launched multiple times. Terran 1 is a small lift launch vehicle, that is, it can carry loads of up to 2,000 kg.

The engine in Terran 1

Terran 1 has  two-stage engine. The first stage uses nine Aeon 1 engines. This engine is powered by a mixture of methane and oxygen. The second stage is powered by the AeonVac engine. This first launch of Terran 1 did not carry any payloads. However, it is capable of carrying payloads up to 1,500 kg to the low earth orbit. The low earth orbit lies at a distance of 1000 km from the earth’s surface. It was built using aluminum alloy.

NASA’s future plans for Terran 1

Although Terran 1 won’t carry any payloads on its maiden flight, NASA has already signed a contract with the company to launch a satellite with the rocket as part of its Venture-Class Acquisition of Dedicated and Rideshare (VADR) missions in the future.

Future goals

The Aeon 1 engines will be replaced with Aeon R engines. The Aeon R engines have higher thrusts. And the Aeon R engines will be capable of powering medium-lift rockets. The medium-lift rockets are those rockets that can carry payloads between 2,000 kg and 20,000 kg.

 

Design

Terran 1 consisted of two stages. The first stage was powered by nine Aeon 1 engines burning methane and oxygen propellants (methalox) in a gas-generator cycle, each producing 100 kN (23,000 lbf) of thrust. The second stage was powered by a single vacuum-optimized version of Aeon 1, known as AeonVac, producing 126 kN (28,300 lbf) of thrust in vacuum. Both stages were autogenously pressurized.

The payload fairing measured 6.8 m (22 ft) long and had a diameter of 3 m (9.8 ft). Terran 1 was capable of up to 1,500 kg (3,300 lb) to low Earth orbit. Relativity commonly stated a payload capacity of 1,250 kg (2,760 lb) to lower inclination low-Earth orbits and 900 kg (2,000 lb) to a sun-synchronous orbit (SSO).

The primary and secondary structures of Terran 1 were manufactured with Relativity’s Stargate 3D printer out of aluminum alloy. 90% of Terran 1 by mass consisted of printed components; Relativity claimed that they could reduce the part count in the vehicle by 100 times compared to traditionally-manufactured rockets and manufacture an entire flight article from raw materials in 60 days. Relativity’s in-development Terran R launch vehicle will utilize the same tooling used to manufacture Terran 1.

Relativity advertised a price per launch for Terran 1 of US$10 million in 2019. The advertised price per launch has been increased to $12 million USD in 2021.

Proposed upgrades

In February 2022, Relativity CEO Tim Ellis stated in an interview with Ars Technica the nine Aeon 1 engines on the first stage could be replaced with a single Aeon R engine with substantially higher thrust. The Aeon R engine is planned to be used on Relativity’s much larger Terran R rocket. Had the vehicle not been retired, the upgrade would have likely been done by the fourth flight.

Launch

Relativity received a Federal Aviation Administration (FAA) launch license to conduct the first launch of Terran 1, not-earlier-than (NET) 8 March 2023 from Cape Canaveral Space Force Station’s Launch Complex 16.^] Originally, another static fire was planned with the full rocket stack before first launch. Relativity believed it performed enough tests and instead attempted a launch. Terran 1’s initial flight scheduled for 8 March 2023 was scrubbed due to “exceeding launch commit criteria limits for propellant thermal conditions on stage two”. A second launch attempt on 11 March was also scrubbed. Set for 18:00 UTC (14:00 EDT), high upper-level winds prevented liftoff for over an hour. A second attempt at 19:35 UTC (15:35 EDT) was canceled at T-70 seconds from a boat in the launch safety range. A third attempt at 19:42 UTC (15:42 EDT) was canceled half a second before liftoff. The engines briefly lit up before shutting down from a “launch commit criteria violation”. A final attempt occurred at 21:00 UTC (17:00 EDT). An issue with the automatic stage separation promptly closed the launch window.

Another launch window for Terran 1’s initial flight opened on March 23. After holding twice from a boat in the launch safety range, and high upper-level winds, the rocket lifted off at 03:25 UTC (23:25 EDT). Following a nominal liftoff and powered flight of the first stage, the second stage failed to ignite, leading to the loss of the mission. Preliminary investigations blamed the failure on a slower-than-expected valve opening as well as vapor ingestion into the liquid oxygen turbopump causing reduced performance. Although the launch did not orbit, Relativity acknowledged the successful performance of the vehicle’s 3D-printed structures under flight loads.

Following the loss of the first mission, the company abandoned further plans for Terran 1, instead choosing to focus efforts on developing the much larger reusable Terran R vehicle. Existing payloads on Terran 1 will likely have to be manifested to Terran R or other flights.

 

Blog By: Trupti Thakur