Far Side of Pluto

Pluto’s Non-Encountered Hemisphere Comes to Light – Far Side of Pluto

After 4.5 years of an unmanned visit to Pluto, you might think we got all from Pluto. But human’s Pluto exploration is not over yet. At least for far side of Pluto!

The New Horizons Spacecraft performed a close flyby to Pluto on 14 July 2015 and it marches on towards Kuiper Belt. Meanwhile the scientists have been working on the data collected by New Horizons and been publishing their new findings about various Pluto facts.

One Pluto day corresponds to 6.4 days on Earth, and this is a challenge for a fast flyby mission to Pluto. Because the cameras can only image one hemisphere of Pluto with best resolution possible. That was well predicted and calculated by mission’s science team and Pluto was also imaged ±3,2 days prior and subsequent to the closest encounter.

Till October 2019, we had low resolution images of the far side of Pluto. However, a new article* published on 22 October 2019 presents improved images of the non-encounter hemisphere and reveals new details about the surface features of the reachless.

Global Pluto Map
New global map of Pluto where the non-encountered hemisphere is centered.

How Was Far Side of Pluto Not Visible Before?

Well, it was not “not visible“. It was in low resolution and just more “blurred“.

On above Pluto map published with this study, the non encountered hemisphere is seperated from the encountered one with a white line. You can see that the resolution dramatically varies between those two zones. Because the best improved resolution for the far side is between 2.2 to 40.6km/pixels while the one for the near side is less than 1km/pixels.

On the other hand, researchers were able to increase the resolution for the far side by calibrating the images. The best way to perform this was to take advantage of the quality images from the neighbourhood on the other side of the white line and to implement accross the border. What is more, scientists indicate that the limb profiles on random coordinates were also very useful increasing the resolution.

Such work did not only increase resolutions of the non-encounter part, but also allowed scientists to point out the geological features.

Geology of Pluto's Far Side
Basic geological features on non-encountered side.

What is New About Far Side of Pluto?

The study reports that the bladed terrains are widely and randomly distributed on the non-encountered side of Pluto. On previous studies, such features were explained to be formed via the sublimation process of surface ices. Similar and methane-made features were also detected on the encountered hemisphere in Tartarus Dorsa. In fact, scientists believe these zones are the most methane-rich zones on Pluto surface.

In addition to above, the new research shows that the bladed terrains cover quite bigger area than previously thought and lay alongside Tartarus Dorsa, forming a huge strip together.

The second biggest crater of Pluto is the Simonelli Crater. This crater was already marked before this study, and is further analyzed on this research. Given the crater was surrounded with bright plains and noting its similarity to Elliot Crater, it’s anticipated that ice residues should also exist on its floor.

Researchers also mention that the the western part of Cthulhu Regio, marked with SP (smooth plains) is one of the oldest surface features on Pluto surface; which might even be older than the big impact to Sputnik Planitia. This is more than 4 billion years.

Another region named Dark Depressions (DD) was also highlighted on the map. Those narrow but long features with low albedo are estimated to be representing sides of the high pits where the mantle is removed via different geological processes like tectonism, sublimation and erosion. However, what is interesting about another potential process not mentioned above is different than any other geological activity predicted before.

Pluto Antipode
Those two images show the antipodal view and we’ll mention about them on below.

Tracking the Signs of a Huge Impact Cracking Pluto Surface

This DD area is right on the antipodal of Sputnik Planitia, which is considered to be the largest impact basin on Pluto. The study claims that such huge impact might have caused a harsh effect on the antipode and have torn the mantle apart!

This theory was demonstrated on above images. The white lines on both images represent the tectonic lineations and the green markings point out their related and resulting alignations. When it comes to the points marked with Play Station buttons, the ones on left symbolize the potential impact areas on Sputnik Planitia. And ones on right side image are the antipodes of those locations.

As seen from the image, relative alignations (in green) stop in the far (non-encountered) side area. Scientists believe they continue all the way covering that hemisphere, however the images with limited resolution prevent them to prove it.

Pluto Map
Our new Pluto map, centered to the “non-encountered” side.

So the speculations throughout these findings and overall evaluation of this scenario strongly suggest that a giant impact to Sputnik Planitia formed a basin bigger than 1000 kilometers in diameter. And the resulting force was densely conducted to its antipode and cracked the surface.

However the researchers mention that they can not be 100% sure of above because of above stated low resolution images.

Conclusion

In terms of clarifying above and Pluto’s overall features, the article concludes with suggesting another orbiter mission to Pluto. The scientists are also counting on the new advanced telescope technologies for detailed images of Pluto from Earth-based or near-Earth observations. However those images will have slightly lower resolutions than the ones obtained from the non-encountered side by New Horizons and will not provide a more detailed analysis.

We’d prefer and love to follow another mission to Pluto! The only handicap here is, although it is not a dream according to Alan Stern (PI of New Horizons Mission), such mission can be practised and performed in two decades time.

References

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