The US space agency's Phoenix spacecraft is now just hours away from attempting its perilous touchdown in the martian Arctic. It's time to see how terrifying those "seven minutes of terror" really are.
We've heard a lot about the difficulty of those last few minutes that will end the Phoenix probe's 122m mile, 10 month journey. It is a crucial time undoubtedly: the probe has to enter the atmosphere at a perfect speed and angle, and then fire parachutes and retro-rockets at exactly the right time if the spacecraft is to stand a chance of surviving touchdown. By 1am BST we should know if Phoenix is safely down.
The mission - to analyse the martian climate, and to check subsurface water ice for signs that the northern region was once habitable - is due to last just three months. Beyond that, there will be too little light for the solar panels to charge the probe.
Nasa has been holding press conferences on the state of the mission at least daily in the run up to landing day. So far - touch wood - all news has been good. A dust storm blowing over the landing site moved on; the probe appears to be operating perfectly. But mission managers are acutely aware that crunch time is fast approaching. Last night, mission manager Joe Guinn summed up the team's sentiment with: "I'm getting a real case of heebie-jeebies." Me too.
