Walk on the warm side

A space suit design that uses coils of water to recycle the body’s warmth will allow astronauts to carry out emergency engineering work outside their capsules with greater ease.

By using human survival and heat control responses, the garment will help workers to minimise energy use while carrying out repairs in the cold of space.

To keep their hands warm during space-walks, astronauts currently wear a second pair of gloves inside their suits.

However, this can make it hard for them to manipulate smaller devices as the padding impedes their sense of touch.

The liquid cooling and warming garment (LCWG) developed by the US Laboratory for Health and Human Performance in Extreme Environments at the University of Minnesota does away with the need for the second pair of gloves by redirecting expelled body heat.

During extreme cold, the body has evolved to ensure that the brain and core of internal organs are kept warm so that they can remain functioning for as long as possible.

This is done by redirecting warmed blood from the core to the head, slowing blood flow to limbs and allowing them to cool, though this affects hand mobility.

The LCWG suit works by directing heated water across key sections of the body through coils of pipes. These cover the top of the head and circle areas such as the wrists, shoulders, ankles and ribs where there is little muscle and fat, yet bones and blood vessels are close to the skin’s surface.

As heat is lost from the head it warms the water that is then circulated to areas such as the shoulders, heating them and allowing warmed blood to circulate to the fingers to retain mobility without wasting energy heating the whole suit.

‘We have used human physiology to insert and remove heat from the body,’ said Dr Victor Koscheyev, principal investigator for the research team.

‘The suit follows a new approach by depending on the body’s reactions rather than concentrating on materials research. It consumes little energy and is also lightweight.’

‘In the cold the limbs may have a temperature of between 25 degrees to 27 degrees C, while the head is around 33.5 degrees. But the body dissipates heat from the head even when the blood vessels elsewhere are constricting, so this can be harnessed to transmit heat from the head back to the hands.’

The water temperature is raised slightly using energy from a small battery connected to the system, while the temperature of the fingers is monitored using sensors embedded in a ring warn by the astronaut.

The system automatically starts to support the hands once a trigger temperature is reached and can also be used to lower body temperature by running cooled water through the coils.

‘In the cold we can aid hand comfort by increasing the temperature by a degree or two,’ said Dr Koscheyev.

‘Through selection of areas to keep warm we minimise power needs as well as having a more economical way of keeping astronauts warm.’