New Horizons: Pluto map shows 'whale' of a feature

By Jonathan Amos
BBC Science Correspondent

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image copyrightNASA/JHU-APL/SWRI
image captionThe map combines images takes between 27 June and 3 July

Scientists have released their latest map of Pluto, using images from the inbound New Horizons spacecraft.

It unwraps the visible parts of the sphere on to a flat projection, giving another view of the features that have started to emerge in recent days.

Evident are the light and dark patches at the equator, including one long dark band being dubbed "the whale".

The US space agency's (Nasa) New Horizons probe is now less than seven days away from its historic flyby.

It is due to pass over the surface of the dwarf planet at a distance of less than 13,000km, grabbing a mass of images and other kinds of scientific data.

The pictures at that point will be pin sharp, showing targets on the surface of the 2,300km-wide body at a resolution of better than 100m per pixel.

In the map on this page, the features are much less resolved. The images from which it was made were acquired between 27 June and 3 July.

They are a combination of shots from the probe's high-resolution, "black and white" camera, Lorri, and its lower-resolution, colour imager known as Ralph.

The whitish area in the centre covers the face of the dwarf planet that will present itself to New Horizons at closest approach.

To the east is the spotty terrain that has generated most discussion so far. Quite what these blobs represent is unclear. Each one is a few hundred km across.

Cradled in the whale's "tail", on the far left of the map, is something that looks like a doughnut. It could be a impact crater or a volcano, although at this resolution any interpretation remains pure speculation.

New Horizons has recovered from its weekend hiccup, in which the probe tripped itself into a protective safe mode and dropped communications with Earth for over an hour.

Engineers say they understand the cause of the computer glitch. This particular type of error, they stress, has now been ruled out for the probe's next few historic days.

image copyrightNASA/jhu-apl/swri
image captionThe spots are part of a dark band that wraps around much of Pluto's equatorial region

It is moving at nearly 14km/s - far too fast to go into orbit on 14 July. Instead, it must gather as much information as it can while it sweeps past not just Pluto, but its five moons as well: Charon, Styx, Nix, Kerberos, and Hydra.

The flyby occurs on the 50th anniversary of the first successful American pass of Mars by the Mariner 4 spacecraft.

By way of comparison, New Horizons will gather 5,000 times as much data at Pluto than Mariner did at the Red Planet.

New Horizons' difficulty is getting all that information back to Earth. The distance to Pluto is vast - more than 4.5 billion km - and this makes for very low bit rates.

It is likely to take 16 months to play back every piece of science acquired over the next week.

The BBC will be screening a special Sky At Night programme called Pluto Revealed on Monday 20 July, which will recap all the big moments from the New Horizons flyby. and follow me on Twitter: @BBCAmos

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