International Space Station astros prepare to rejoin us Earthlings

Human guinea pigs to be subjected to more testing after arrival

Three astronauts from the International Space Station are expected to fly home tomorrow after spending 172 days floating in space.

Expedition 48 Commander and NASA astronaut Jeff Williams, Soyuz commander and Flight Engineer Alexey Ovchinin and Oleg Skripochka from Roscosmos, the Russian space agency, will leave the ISS in the Soyuz TMA-20M spacecraft.

The team will depart at 5:51pm ET (10:51pm BST) and arrive in Kazakhstan at 9:15 pm ET (2:15am BST).

NASA will be live streaming the event at 9:00am ET (2:00pm BST). Viewers will get to watch a replay of the handover ceremony as space veteran Jeff Williams passes station command to Anatoly Ivanishin, captain of the 49th team to the ISS.

Jeff Williams holds the current US record and will have spent 534 days in space – longer than any other American astronaut.

Known as “Grandpa Astronaut”, Williams swapped a career as a colonel in the US Air Force for NASA when he was selected as an astronaut at 38 years old.

Together with the 49th team, cosmonaut Anatoly Ivanishin, NASA astronaut Kate Rubins and Japanese astronaut Takuya Onishi, the six will carry out more than 200 scientific experiments.

Last week, it was announced that Rubins had sequenced DNA in space for the first time.

One particular interest when the 48th team returns to terra firma is to check the effects of space on the human body.

The mechanisms responsible for bone and muscle loss, immune system changes, and fluid distribution are especially important if space agencies plan on blasting humans to outer space for more complex missions that will last longer than six months.

The landing coverage begins at 8:00pm ET (1:00am BST) and Williams will be available for a post-landing interview at 12:00pm ET (5:00pm BST) the next day. ®

You can watch it here.