Back to the Moon. Technical design and main tasks of the Artemis I mission

The year 2022 gave space enthusiasts a show that was last seen half a century ago. We mean the super-heavy SLS rocket installed on the launch pad, which will send the Orion spacecraft to the Moon as part of the Artemis I mission. Since preparations for the launch have already entered its last stage, we would like to tell you more about this mission and its main tasks.

SLS rocket

SLS is NASA’s largest rocket since the Apollo program. The height of the basic modification (Block 1 version) is 98 meters. The launcher consists of two solid-fuel side boosters and two stages.
The SLS rocket and the Orion spacecraft against the background of the moon. Source: NASA

The SLS side boosters are built by Northrop Grumman and are a modified version of the units that were installed on the shuttles. They differ from them with the presence of an additional segment.

The first (central) stage of the SLS is built by Boeing. It is equipped with four modified RS-25 engines that run on liquid hydrogen + liquid oxygen rocket propulsion. Previously, these power units were also used on shuttles.

The second (upper) stage of the SLS is the DCSS (Delta Cryogenic Second Stage) cryogenic block, which was previously used on the Delta family of rockets.
SLS first stage warmup. Source: NASA

The Block 1 configuration of the rocket can deliver 95 tons of cargo to low Earth orbit (LEO) and up to 27 tons of cargo to the lunar trajectory. Starting with the fourth flight, the SLS will be upgraded to the Block 1B version. Instead of the DCSS cryogenic unit, the EUS (Exploration Upper Stage) upper stage by Boeing will be installed on it. It will allow the rocket to lift as much as 105 tons to the ISS and up to 42 tons to the Moon. In the future, NASA hopes to further update the design of the second stage of the SLS and the side boosters, so that its payload will be increased up to 130 tons to the ISS and up to 46 tons to the Moon.

Orion ship

The development of the Orion spacecraft began in the twenty-hundreds as a part of the Constellation program (it was later closed). It consists of a residential module built by Lockheed Martin and a service compartment created by the Airbus Defense and Space company.
Installation of the Orion spacecraft on the SLS rocket. Source: NASA/Frank Michaux

The weight of the Orion residential module is 104 tons. It is designed for a crew of four astronauts. In 2014, NASA performed an orbital test of the spacecraft’s residential module, during which it made two loops around our planet and then entered the Earth’s atmosphere at a speed of 8.9 km/s (this is less than the speed of the return from the Moon, but more than the speed of normal flights to Earth orbit). The thermal protection of the ship successfully coped with this test.

The Orion service module is based on the unmanned ATV vehicle that once supplied the ISS. It carries all the necessary supply of air and water for the crew, as well as batteries and four photovoltaic panels designed to generate electricity. Its length is 4 meters, its diameter is 4.1 meters (19 meters, taking into account the unfolding solar panels), its mass when fueled is about 15 tons, of which about 9 tons is fuel for onboard engines.
Technical design of the Orion spacecraft. Source: NASA

The basis of the power plant of the service module is the AJ10-190 engine, which was previously used in the orbital maneuvering system of the shuttles. It can provide Δv up to 1800 m/s. It will also be equipped with 8 auxiliary Aerojet R-4D-11 engines and 24 small guidance system engines.

Orion is equipped with an emergency rescue system in the form of a solid-fuel rocket mounted in its nose. In the event of an accident, it must “pull out” the ship and move it away from the perishing launcher. In 2019, NASA successfully tested the system. It is worth noting that during the Artemis I mission, the Orion emergency rescue system will not be activated.

Artemis I flight plan

The main task of the Artemis I mission is comprehensive testing of all SLS and Orion systems. A successful test would pave the way for manned flights in which four astronauts would fly around the Moon (Artemis II mission) and then land on the Moon’s south pole (Artemis III mission).
The intended orbit and basic maneuvers of the Orion spacecraft during the Artemis I mission. Source: NASA

The Artemis I flight plan looks like this. After entering Earth orbit, Orion will perform a maneuver that will put it on a flight path to the Moon. The spacecraft will fly within 100 km of the lunar surface, after which it will activate the main engine. A combination of lunar gravity and several subsequent maneuvers will allow it to enter a distant retrograde orbit (DRO) around the Moon.

The DRO lies at a considerable distance from the lunar surface — at the apogee the ship will be as far as 70 thousand km from the satellite of our planet, while moving in the opposite direction of the Moon’s movement around the Earth. Mission specialists chose this orbit because of its stability. The space vehicles in it are “balanced” by the gravitational attraction of the Earth and the Moon, which allows reducing fuel consumption.

Orion will spend several weeks in the DRO. During this time, NASA engineers will monitor the rover’s behavior and test its systems. To return to Earth, Orion will use its engine twice. The first ignition will take it out of the DRO and send it on a trajectory during which it will again pass within 100 km of the lunar surface. The ship will then perform a final maneuver directing it to Earth.
The Orion spacecraft adapter carrying the Artemis I payload. Credit: NASA/Cory Huston

The last test will be the entry into the Earth’s atmosphere. As Orion travels at 11.2 km/s, its heat shield will heat up to a temperature of about 2,800°C. If everything goes well, the capsule of the ship will be lowered into the Pacific Ocean.

Mission payload

During the flight, Orion will carry a set of sensors to carefully record the level of G stress and radiation that the astronauts would experience during the flight. The role of the crew will be performed by the Moonikin Campos mannequin dressed in a spacesuit, as well as the torsos of Helga and Zohar. They will be equipped with sensors that will measure the level of exposure to radiation and G stress.
Dummies that will go to the Moon as part of the Artemis I mission. Source: NASA/Frank Michaux

A container with plants and algae will also be placed inside the ship. It is part of an experiment to study the effects of radiation on living organisms in interplanetary space.
Microchips with the names of people who worked on the preparation of the Artemis I mission. Source: University of Houston/Dr. Long Chang

Orion will also carry a number of symbolic payloads. Among them, the flags of the United States and European countries, a set of four Lego figures, a statuette of the goddess Artemis, dolls of Snoopy the dog and Shaun the sheep (they will be used as indicators of weightlessness), as well as microchips and flash drives with the names of project employees and people who participated in the Fly Your Name Around The Moon promotion.
Shaun the Sheep doll, which will go to the Moon on the Orion ship. Source: ESA

In addition to Orion, SLS will also launch payloads in the form of ten microsatellites based on the CubeSat platform. Here is the list:

  • Lunar IceCube. This device will search for deposits of water and other volatile compounds on the Moon.
  • LunaH-map. The goal of this mission is to create maps that show the presence of traces of hydrogen in the permanently shadowed craters at the south pole of the Moon.
  • LunIR. A satellite that will take detailed infrared images of the lunar surface.
  • OMOTENASHI. A Japanese lander designed to measure radiation levels. If successful, it will be the smallest spacecraft in history to land on the Moon.
  • CuSP. A satellite for determining the characteristics of charged particles and magnetic fields.
  • Apparatus intended for a biological experiment to study the effects of radiation on living beings.
  • EQUULEUS. A Japanese satellite for studying the radiation situation in the vicinity of the Lagrange point L2 of the Sun-Earth system.
  • NEA Scout. An experimental solar sailplane that is supposed to make a flyby of a near-Earth asteroid.
  • ArgoMoon. An Italian device that will take pictures of the worked out DCSS cryogenic unit.
  • Team Miles. Demonstrator device intended for testing an experimental plasma power plant.

Artemis I launch date

As for now, the launch of the Artemis I mission is scheduled for August 29, 2022. Reserve launch windows will be open on September 2 and 5. If the rocket fails to launch on those days, the next launch windows for a flight to the moon will be open between September 20 and October 4 and October 17 and October 31.

Ракета SLS
The SLS rocket on the launch pad. Credit: NASA/Ben Smegelsky

The flight plan intends that Orion will spend 42 days in space. If the SLS launch takes place on August 29, the craft will return to Earth on October 10.