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New Horizons II

July 10, 2015

Operating a spacecraft on the edge of the solar system is a tricky business.

Consider New Horizons, a small craft that’s taking aim at Pluto. It’s three billion miles away right now. At that range, it takes radio signals from the craft about four-and-a-half hours to reach Earth. So if anything goes wrong at the last minute, no one on Earth can help.

To minimize the chances of a last-minute hiccup, flight controllers worked out the sequence of events for the Pluto encounter two years ago. They transmitted the instructions, then ran through a full rehearsal while the craft was still months away.

Another problem is that the craft’s radio signal is so weak by the time it reaches Earth that it’ll take 16 months for New Horizons to transmit all of its observations. So if there are any problems over that time, much of the probe’s work would be lost.

And yet another problem with the distance is that sunlight is only about a thousandth as intense at Pluto as it is here on Earth. So it’ll take a long time for New Horizons to snap each picture.

Still, mission scientists expect a bounty from New Horizons — some of it predictable, but some of it not. Hal Weaver is one of those scientists:

WEAVER: We really are doing this for the first time. And, almost certainly, the most exciting discoveries that we’ll make in this mission are the ones that we never anticipated.

We’ll find out about those discoveries — anticipated or otherwise — beginning next week.


Script by Damond Benningfield, Copyright 2015

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