Given the risks inherent in space missions, this seems like a good moment to draw attention to the New Horizons (NH) probe, which is approaching Pluto. If we wait a few weeks – by which time things could have gone awry – we may not be able to focus on the achievement of getting the fastest spacecraft ever launched to the furthest reaches of our solar system.
Many space missions run into unexpected problems. As Richard Branson put it last year, when Virgin Galactic’s SpaceShipTwo crashed, “Space is hard.” There was the Apollo 13 incident and the near-disaster of the European Space Agency’s SOHO mission, in which the solar observatory satellite’s control system went awry. On 28 June, we discovered again that space is hard when SpaceX’s Falcon 9 rocket disintegrated shortly after take-off on a mission to resupply the International Space Station.
With NH, which launched nearly a decade ago, it’s so far, so good. On 14 July, after a three-billion-mile journey, the probe will fly past Pluto at a distance of less than 8,000 miles – assuming that its navigation works until the end. To get a feeling for how hard this is, consider the manoeuvres carried out in mid-June. Radio tracking data, which takes four and a half hours to reach earth from NH, showed the need for a velocity adjustment. The signal to fire the thrusters for 45 seconds took another four and a half hours to reach the probe. Then NH communicated its status: another wait for news.
As the probe gets closer to Pluto, such adjustments will become increasingly crucial. We are now in “approach phase three”. It is exciting, because we are seeing Pluto and its moons in unprecedented detail, but it is also nerve-racking. We may discover dust rings or hitherto-unknown moons that pose a danger to the spacecraft. And, after almost a decade, we could still lose everything.
NH could drift off course, missing its optimal rendezvous point. After 4 July, there will be nothing we can do. NH takes photographs of Pluto every day and sends these back to mission control. The relative positions of the stars in the background allow the team to calculate the probe’s position. Yet they don’t help when it comes to deciding how far the probe is from Pluto. That must wait until Pluto is close enough that its position in the pictures moves sideways relative to the background stars. However, once that can be seen, it will be too late to do much about any problems with its trajectory. The only thing to do if the craft turns out to be closer than anticipated is to switch on its scientific instruments and get straight to the task of taking data.
This will be beamed back to us as NH continues its journey. It will employ what is perhaps the greatest unsung achievement of modern times: the Deep Space Network. All the data coming from distant spacecraft is channelled through three telescopes – in California, Madrid and Canberra – that work together to keep in constant contact with the missions revealing the secrets of our solar system. They were vital in resolving the crisis on Apollo 13 and in rescuing the SOHO mission.
Because of the distances involved and the limited power of NH’s antenna, new information about Pluto will arrive at roughly one kilobit per second, thousands of times slower than your internet connection. The whole transmission will take more than 16 months. Space is hard but deep space is perhaps harder – yet, as we hope to find out, still worth the effort.
UPDATE: New Horizons put itself into “safe mode” on 4 July, after receiving subtly misprogrammed commands. A short while later, it returned to full operation: everything is on track for full data collection at the Pluto flyby on 14 July.
Content from our partners
Related
This article appears in the 01 Jul 2015 issue of the New Statesman, Crisis Europe