Preserving digital information can be a tricky business – indeed the problem is so complex, scientists at US space agency NASA implemented a data retention policy that fixes deletion dates for different classes of data.

Like many IT departments, the team at NASA has recognised that the cost of retaining many data files is greater than the value of that data to the organisation – especially when the equipment needed to extract the data is obsolete.

But NASA's decision to purge files has upset some in the space community. Members of The Planetary Society, a space exploration interest group, are horrified that the agency is about to discard all of its old 7- and 9-track magnetic tapes that hold data on its Pioneer missions. And the Society has even set up an appeal to try to save the tapes.

The missions date back to the 1970s, and it appears that NASA is the only owner of working equipment capable of reading the antiquated media. That means the Planetary Society is going to have to cough up for the bulky tape drives or be left with reels of useless binary data.