Posted July 13, 2015

Countdown to Pluto, red planet with wobbly moons

Tension is building for outer solar system aficionados and dwarf planet lovers. Just a few days from now, on the 14th of July, the New Horizons spacecraft will fly by Pluto. We have learned so much already and the climax is still to come. This is a very recent image:

We've seen the best pictures ever of the distant, enigmatic dwarf planet and now a crude map can be drawn.

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What's more, we know now that this icy place is not blue or grey, as it has been pictured for years, but reddish like Mars. Its surface has distinct regions hundreds of miles across, one shaped like a whale (bottom left), another resembling a heart (bottom right).

Plutos moons tell a remarkable story too. So complicated are the games gravity plays that some of the moons tumble around totally chaotically. Here's an animation by NASA of the moves of one moon, called Nix (really!). Give me a living room thingy that mimics this and I won't need a tv ever again...

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Most pictures of Pluto will probably look well lit. But don't be fooled. Scientists tweaking the buttons of digital imaging software can use any amount of light they damn well please, but as Nasa explains here, the light of day on Pluto would be very dark indeed, about a thousandth of broad daylight on Earth.

That's bad news for New Horizons itself by the way. One thousandth the light means you need a thousand times the exposure time that you would down here. And time is really, really short. New Horizons will come as close to Pluto as 12,500 kms but will do so at a speed of almost 50,000 kms per hour. So there will be only a few minutes to take the best resolution pictures. Mapping will start about three days before closest approach.

Why not fly by at a lower speed? Why not go into orbit and have all the time we like? Either that would require lots of fuel to decelerate, which would have made the craft prohibitively heavy, or New Horizons would have had to travel at a much lower speed all the way to Pluto. And the journey has taken nine years already... We can't have it both ways, the cosmos is still a bit stronger that we are.

Can we follow the encounter live, on the 14th? No, there you have another thing you can't do. Light and radio waves need almost five hours to make it to Earth. Also, the bandwidth available will be about 1 kilobit  per second. That's dial-up modem speed AD 1990. So expect the pictures to trickle down very slowly over the course of a whole year. After that, some memory will be freed up for this interesting re-use which we discussed previouslywe discussed previously.


About Herbert Blankesteijn

Herbert Blankesteijn is a technology journalist from the Netherlands who has written for many prominent Dutch newspapers. He presented and directed television and radio programmes and has 10 books to his name. Herbert is interested in nascent fields such as 3D printing, drones, robotics and the private space business.