The two DLR radiation measurement mannequins Helga and Zohar are now ready for their flight to the Moon and back. © NASA
12. December 2022
They returned from the Moon on a Sunday: Last night the two phantoms Helga and Zohar on board the NASA's Artemis I Orion spacecraft splashed down in the Pacific Ocean off the coast of California. This ended the 25 days space journey of the two astronaut phantoms and their companions to the Moon, in lunar orbit and back to Earth. Together with the NASA mannequin ‘Commander Moonikin Campos’ and the mascots Snoopy and Shaun the Sheep, they formed the test crew of the first Artemis flight.
The #LunaTwins of the MARE project, led by the DLR Institute of Aerospace Medicine, measured cosmic radiation throughout the entire journey: “Helga and Zohar have travelled a long way aboard the Orion spacecraft. On their far-flung lunar orbit, they were at times almost 400,000 kilometres from Earth,” says Thomas Berger, head of the MARE experiment at the DLR Institute of Aerospace Medicine. "In some cases, the trajectory took them to regions that no crew-worthy spacecraft had ever reached before. Now we are eagerly awaiting to get them back and to start the evaluation of the radiation measurement data."
Test run in lunar orbit
Since the launch of Artemis I on 16 November 2022, the Orion spacecraft has completed an extensive test run. The first close lunar flyby took place on the sixth day of flight (21 November), during which the Orion spacecraft approached the lunar surface to a distance of 128.7 kilometres. On 25 November, the spacecraft entered Distant Retrograde Orbit (DRO), which was to be tested with this flight. Then, on 26 November, Orion broke the record set by Apollo 13 for the furthest distance from Earth travelled by a spacecraft designed for humans (400,171 kilometres) and reached its maximum distance from our home planet (434,522 kilometres) on 28 November. Another close flyby of the Moon took place on 5 December, also at an altitude of 128.7 kilometres. During this flyby, the moon's gravitational pull was used to help Orion on its way back to Earth. Shortly before the re-entry on 11 December, the crew module and the European Service Module ESM separated. The crew module returned to Earth, while the service module burned up in the Earth's atmosphere during re-entry over the Pacific Ocean.
Passive and active radiation sensors
Helga and Zohar have been measuring radiation levels throughout their entire mission. The two measuring mannequins are modelled on the female body, including reproductive organs, in order to measure the radiation dose experienced by organs that are particularly sensitive to it. The female astronaut phantoms, each consisting of 38 slices, are 95 centimetres tall and weigh 36 kilograms. Zohar, provided by the Israeli Space Agency ISA, weighs 62 kilograms with an AstroRad radiation protection vest from the company StemRad. Inside two phantoms are organs and bones made of tissue-equivalent plastics that mimic the varying density of bones, soft tissue and lungs. More than 12,000 passive radiation detectors made of small crystals have been installed in these ‘organs’ and on the mannequins’ surfaces, as well as 16 active detectors from DLR in the body's most radiation-sensitive organs – including the lungs, stomach, uterus and bone marrow. By reading out the crystals, a three-dimensional image of the human body is created, revealing the total radiation exposure to different parts of the bones and organs during a flight to the Moon and back.
This treasure trove of data was recovered with the Orion capsule after its landing in the Pacific Ocean. The still sealed Orion capsule will be transported to NASA's Kennedy Space Center in Florida where the capsule will be opened by the NASA team. “Once the capsule has been recovered, Helga and Zohar will be handed over to the MARE team. This is likely to take place in the second week of January 2023,” says Berger. “The data from the active measuring instruments will be read out on site so that we can quickly get a first impression of the radiation dose received during the mission.” The passive sensors will then be evaluated after the #LunaTwins have returned to the DLR Institute of Aerospace Medicine in Cologne, which is planned for the beginning of February 2023.
Die DLR press release can be found here: The first female ‘astronauts’ return from the Moon - DLR Portal