After the final message has been collected on Sunday 23 August 2009, all the messages will be collected and exported as a text file and sent to NASA's Jet Propulsion Laboratory in California, where it will be encoded into binary code, packaged and tested before transmission. This system of beeps and pauses (on and off radio signals) will be sent back to Australia to the NASA/CSIRO Canberra Deep Space Communication Complex at Tidbinbilla, near Canberra. Over the past 37 years, the 70-metre main antenna, known as Deep Space Station 43, has supported many missions exploring our Solar System and beyond, including keeping in touch with the Apollo astronauts, providing two-way radio contact with the Mars Exploration Rovers, and deep-space missions such as the twin Voyager spacecraft and NASA's New Horizons probe to Pluto and the Kuiper Belt. DSS43 will transmit the signal to Gliese 581d on 24 August 2009. When will the messages arrive?
The signal will reach the solar system of Gliese 581 (the parent star) around December 2029 give or take a few months. Despite travelling at the speed of light, the radio signal will need to cross 20.3 light-years 192 trillion km of interstellar space before reaching the planet. It sounds like a long way, but Gliese is one of the 100 closest stars to Earth, making it our best target for sending and hopefully receiving a message within our lifetimes. Any response will need to travel the same way back, so unless Gliesans have improved communication technologies, the soonest we could hope to receive an answer would be in 42 years around 2051.