Astronaut Timothy Kopra talks to his sister, Lauri Kopra, and her husband, Aaron Mashoian. The video downlink was provided by Nasa's Ames Research Center.

Part of the technology that has speeded up communications to the station is from the virtualisation specialist Citrix. Astronauts can remotely view a virtual desktop and send data, such as emails and tweets, from datacentres on Earth. Keyboard and mouse commands are relayed via satellite links.

Japanese astronaut Soichi Noguchi, who is currently in the space station, has remotely uploaded tweets and YouTube videos.

The Nasa network that links the International Space Station to Earth uses Xen desktop virtualisation and WAN optimisation using Citrix Branch Repeater. The Citrix technology was first used last month by Expedition 22 Flight Engineer TJ Creamer. Previously, tweets had to be emailed to the ground, and then distributed, due to latency issues.

Expedition 13 Nasa space station science officer and flight engineer Jeffrey Williams uses a computer in the Destiny laboratory of the International Space Station.

The space station moves fast — it orbits the Earth approximately every 90 minutes. This used to cause a Doppler effect, which caused some latency and communications issues before Nasa updated its relaying system, said Citrix Xen Desktop product marketing manager Calvin Hsu.