Constructed by Airbus under contract with the European Space Agency (ESA), the ESM-3 is essential for the mission, supporting a crew of four astronauts during their three-week journey. It will sustain the crew from the time they leave Earth's orbit, through their lunar orbit operations - including docking with the Human Landing System (HLS) - and their safe return to Earth.
Temperature Regulation in the Harsh Space Environment
The extreme cold of space, where temperatures can plunge to -200C, requires precise thermal management to keep astronauts comfortable and equipment functioning optimally. "To manage the temperature in the crew module and the ESM, we have developed a thermal control system," explained Matthias Gronowski, Airbus Chief Engineer for Orion-ESM. The system uses a heat exchanger to transfer heat from the crew module to the ESM, which then dissipates it into space via radiators. This ensures that the crew module remains at standard room temperature, while equipment in the ESM operates within a controlled range of 20 to 60C.
Additionally, multi-layer insulation (MLI), the white blanket covering Orion, reflects solar radiation and insulates the spacecraft, maintaining the internal temperature and protecting it from external thermal fluctuations.
Supporting Basic Life Needs
In addition to thermal protection, the ESM provides essential life support systems, including breathable air and drinking water. The module stores 30 kilograms of nitrogen and 90 kilograms of oxygen to replicate Earth's atmosphere within the crew module, allowing astronauts to breathe. "We need to create an atmosphere similar to the one on Earth, which means we need the right mix of nitrogen and oxygen in the cabin," Gronowski stated.
Nitrogen also pressurizes the drinking water tanks, enabling water distribution aboard the spacecraft. The ESM-3 includes a 240-liter water tank as the primary source of drinking water for the astronauts.
Powering Orion with Solar Energy
Unlike the Apollo missions, which relied on fuel cells, the Orion spacecraft is entirely solar-powered. Its four solar arrays generate 11.2 kW of power - sufficient to supply two average households on Earth. "Of that 11.2 kW, we use about 10% for the ESM components and the remaining 90% goes to the batteries and equipment in the crew module," said Gronowski. The Artemis I mission showed that the solar panels produced more energy than anticipated, a surplus that will be beneficial as the Artemis program advances.
The energy stored in the crew module's batteries is crucial, especially during periods when the spacecraft is in an eclipse and solar power is unavailable. The batteries also power the crew module after it separates from the ESM at the mission's conclusion.
Advanced Avionics for Autonomy
The avionics system aboard the Orion spacecraft offers high levels of autonomy, allowing astronauts to focus on critical tasks. These systems manage functions like temperature regulation and solar array positioning to track the Sun. "In principle, the whole spacecraft can fly the mission completely autonomously," Gronowski noted, though Artemis III will allow astronauts to manually dock with the Human Landing System.
Propulsion: 33 Engines Driving the Mission
After separating from the launch vehicle, the Orion spacecraft will rely on the 33 engines aboard the ESM for thrust and maneuvering. The main engine, a Shuttle-era orbital maneuvering engine provided by NASA, delivers 26.5 kilonewtons of thrust - sufficient to lift a van - enabling the spacecraft to exit Low Earth Orbit and initiate the translunar injection burn toward the Moon. In addition, eight auxiliary thrusters provide backup and trajectory adjustments, while twenty-four smaller engines manage attitude control, essential for maneuvers like docking.
"All 33 engines receive the same propellant from the same tanks via different diameters of tubes, using a helium pressurisation system," Gronowski explained.
Developing the ESM is a complex engineering challenge, involving numerous components and subsystems that must meet stringent standards. Over 100 Airbus team members contributed to its creation. "Contributing to humanity's return to the Moon and being part of this historic moment is a huge source of pride for all the European Airbus teams and the supply chain," Gronowski concluded.
Related Links
Orion European Service Module
Mars News and Information at MarsDaily.com
Lunar Dreams and more
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