Testing the value of artificial gravity for astronaut health

Test subjects in Cologne, Germany will take to their beds for 60 days from 25 March as part of a groundbreaking study, funded by European Space Agency ESA and US space agency NASA, into how artificial gravity could help astronauts stay healthy in space. Carried out at the German Aerospace Center's (DLR) :envihab facility, the long-term bedrest study is the first of its kind to be conducted in partnership between the two agencies. It is also the first to employ DLR's short-arm centrifuge as a way of recreating gravity for participants. But just how easy is it to stay in bed for 60 days and what is the relevance of adding artificial gravity for space researchers? We pull back the covers on this unique investigation as preparations get underway. Bedrest has long been used to mimic some of the changes our bodies experience in the weightlessness of space. Humans are made to live on Earth and without the constant pull of gravity it is common for muscles and bones to start wasting away. Currently, astronauts on board the International Space Station exercise for up to 2.5 hours per day and maintain a balanced diet to help mitigate microgravity's effects, but scientists believe adding a dose of artificial gravity could be key during longer-term missions. Though it may sound simple for the 8 male and 4 female volunteers involved, lying in bed for a full 60 days, plus a further 29 days of acclimatisation and recovery, is not quite as restful as it seems. Throughout the course of the study, all 24 participants will need to remain at :envihab on the DLR campus. There they will be kept in beds with the head end tilted 6 below horizontal and must ensure one of their shoulders is touching the mattress at all times.

As blood flows to their heads and muscle is lost from underuse, researchers will investigate changes and test techniques from diet to physical exercise. Artificial gravity is one of the techniques under the spotlight this time around and will see some of the participants sent spinning.

Recreating gravity
Once a day, a selection of the study's participants will lie in DLR's short-arm centrifuge. There they will be spun to encourage blood to flow back towards their feet and allow researchers to understand the potential of artificial gravity in combating the effects of weightlessness.

The intensity of the centrifugal force is able to be adapted to each person according to their size. DLR can also adjust the centre of spin so that subjects are spun around their heads or their chests. Changing the position in this way could have far-reaching consequences for rehabilitation but, as this is a new domain, these consequences are currently unknown.

A number of different experiments will be carried out over the course of the study, looking at cardiovascular function, balance and muscle strength, metabolism and cognitive performance among other factors. Seven of these experiments will be conducted by European-led research groups, with a view to validating the findings on the International Space Station during future missions.

An international effort
ESA team leader for research Jennifer Ngo-Anh says the international nature of the long-term bedrest study reflects the international collaboration necessary as ESA plans future missions to the Moon and beyond.

"To make these missions possible, various risks to astronaut health must be minimised. This study allows us to address the issue of muscular atrophy caused by weightlessness, but also other stressors such as cosmic radiation, isolation and spatial restrictions."

ArianeGroup signs contract with ESA for future Prometheus engine

Prometheus is a European demonstrator for a very low cost reusable engine, running on liquid oxygen (LOx) and methane. It is the precursor for future European launcher engines as of 2030. The aim is to be able to build future liquid propellant engines with a unit cost of about 1 million euros, or 10 times less than the cost of producing existing engines such as the Vulcain2. The success of this type of technological challenge demands an entirely new approach and the use of innovative design and production methods and toolsApart from switching from the traditional Ariane propellant (transition from the liquid oxygen and liquid hydrogen combination to a combination of liquid oxygen and methane), the demonstrator will entail major developments, including digitilization of engine control and diagnostics, and manufacturing using 3D printing in a connected factory environment. The 75 million euro contract signed by Daniel Neuenschwander, Director of Space Transportation at the European Space Agency (ESA), and Alain Charmeau, CEO of ArianeGroup, the 50/50 joint-venture set up by the Airbus and Safran groups, covers the design, manufacturing and testing of the first two examples of the Prometheus demonstrator.

The French space agency (CNES) is leading in the early design process, and testing is scheduled on the P5 test bed of the German Aerospace Centre (DLR) in Lampoldshausen, Germany, as of 2020.

"The development of Ariane 6 is ontrack, with a first flight scheduled for 2020. This new Prometheus contract with the European Space Agency is paving the way for the future of European launchers, with the goal of designing and building a reusable engine for one tenth the cost of today's Vulcain2 type engines. I therefore thank ESA and the Member States for their contribution and their confidence in entrusting us with the development of the European technology of tomorrow."

Following the initial phase which was completed in early December, the first Program Review confirmed the consistency of the design choices with engine specifications and in particular with the recurring cost targets. At the same time, subsystems testing has started with the gas generator campaign (one of the parts built using 3D printing) on the DLR's P8 test bed in Lampoldshausen.