
Fresh Look at New Horizons Data Shows Plutos Far Side in Unprecedented Detail - makaimc
https://gizmodo.com/fresh-look-at-new-horizons-data-shows-pluto-s-far-side-1839303714
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jessriedel
My personal favorite astronomical image of all time is this view taken by New
Horizon during its retreat from Pluto:

[https://en.wikipedia.org/wiki/File:PIA19948-NH-Pluto-
Norgay-...](https://en.wikipedia.org/wiki/File:PIA19948-NH-Pluto-Norgay-
Hillary-Mountains-2050714.jpg)

It shows atmospheric haze and the curvature of the planet in the same picture
as stark terrain features. (It's a real image; not a reconstructed 3D
visualization.) The Hillary Montes break into the limb (skyline) near the top
of the image.

~~~
yig
Any idea why it appears black and white? The links say it was taken with the
"Multispectral Visual Imaging Camera (MVIC)", whose description suggests it
can capture in visible spectra. Is Pluto really made of grey?

~~~
avian
Very likely the image was taken using only one MVIC filter (it has seven
according to Wikipedia) [1] and is hence monochromatic.

Since this is near sunset and hence very dark, maybe they chose one of the
panchromatic filters to admit as much light to the detector as possible.

Another possibility is that researchers didn't think there was any scientific
value in capturing the image through multiple filters and rather saved the
limited on-board memory for some other data.

[1]
[https://en.wikipedia.org/wiki/Ralph_(New_Horizons)#Specifica...](https://en.wikipedia.org/wiki/Ralph_\(New_Horizons\)#Specifications)

~~~
dr_zoidberg
It's a composite of LORRI images, which is panchromatic. That means it doesn't
have any filters in between, and it measures the intensity of light across all
visible wavelengths (and probably a bit of near IR -- so panchromatic), that's
why it's grayscale -- it's measuring the intensity of light.

I've downloaded all the mission LORRI and MVIC raw files, and I know "by eye"
that MVIC isn't near as good resolution as LORRI.

Edit: after checking the linked file, then yes, this version must be an
upscaled MVIC image (I saw an almost 7k by 3k image and immediately thought of
LORRI). Yet, there are same views from the LORRI instrument, which are far
more detailed.

~~~
jessriedel
Are you saying there is a version of this photo at even higher resolution? Is
there anything you could tell me that would help me track it down? It's sort
of a hard thing to Google for, and hunting through the raw NASA database seems
like a needle in a haystack.

EDIT: Based on this, I think you might have just gotten the two cameras
confused :)

> LORRI is a simple camera to understand -- it's point and shoot. It is black-
> and-white, with a square detector, 1024 pixels square, over an extremely
> narrow field of view of 0.29 degrees....Sometimes, to keep file sizes small
> and improve signal in low light situations, you can bin LORRI images 4x4, so
> the resulting pictures are 256 pixels square. That's pretty much it for
> LORRI....

> MVIC is quite different from LORRI...The detector is 5024 pixels wide, of
> which 5000 are actually photoactive, so its images are 5000 pixels wide by
> an arbitrary number of pixels long.

[https://www.planetary.org/blogs/emily-
lakdawalla/2015/091713...](https://www.planetary.org/blogs/emily-
lakdawalla/2015/09171318-spectacular-new-horizons-mvic-haze.html)

~~~
dr_zoidberg
Didn't confuse them, LORRI is basically a camera at the end of a long
telescope, hence it gives higher resolution images.

But yeah, going over the files at the time this MVIC image was generated,
LORRI took a few (very) close up images but it doesn't have any one having
such a large field of view (since MVIC is not as magnified, then it's able to
take such widefield images).

Edit: And after a lot of searching, I found the image: nh-p-
mvic-3-pluto-v3.0/data/20150714_029918/mp2_0299181722_0x530_sci.fit.

By the way, I'm glad you threw me into this search. Having found this specific
image gave me a few good ideas to work over them again, with new things I've
learned since the last times I visited them.

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droithomme
Interesting about the 1000 ft tall ice shards. The article mentions a possible
orbiter mission to Pluto. Is it even possible? The spacecraft would have to
either massively decelerate at the end of the mission, meaning take a huge
amount of fuel with itself, or would have to travel much slower, with the
mission possibly taking decades to arrive.

In 2017 some astrophysicists met to discuss a possible orbiter mission:

[https://www.space.com/36697-pluto-orbiter-mission-after-
new-...](https://www.space.com/36697-pluto-orbiter-mission-after-new-
horizons.html)

They've also discussed a Charon lander, but seem to be now preferring an
orbiter with a complex dual-object orbit.

In 2017 they decided to firm up the plan so they can make a formal proposal at
a 2020 meeting where NASA decides what it wants to do over the next decade. So
we likely will hear a lot about how this would work next year.

~~~
drjesusphd
"Travelling much slower" isn't really an option either. By the time a craft
encounters Pluto, the problem is that it's going _too_ slow. It then has to
match the (higher) orbital speed, and Pluto's gravity is not helping much.

~~~
droithomme
You bring up a good point regarding the relative speeds.

Pluto on average travels 4.7 km/sec or 16,800 km/hr.

New Horizons, on a 9 yr mission to arrive, was traveling 50,700 km/hr as it
passed Pluto. So it was going much faster than Pluto, however it was passing
almost orthogonal to Pluto's trajectory.

It seems an orbiter would want to arrive using some complex slingshot mission
around various solar system objects, and taking a catch up trajectory that
approaches Pluto more tangentially to its orbit rather than orthogonally.

That seems more doable than when I first balked at this. Since gravity
assist/slingshots can be used to slow down as well as speed up perhaps it
zooms out there fast, then slingshots to nearly meet the speed and direction
of Pluto, meeting up with it at its orbital path sideways and only needing a
small correction at the end to insert itself into orbit.

~~~
T-hawk
Matching speeds to the target object isn't all that difficult, right. The
problem is the travel time becomes enormous to a distant target object,
because it's going so slow comparatively.

Pluto's orbital period is 248 years. If you aim to match its velocity when you
arrive, the journey takes a significant fraction of those 248 years. Compare
Mars, where the orbital period is 22 months, and a Hohmann transfer orbit
takes 9. A similar trajectory to Pluto would be on the order of 80 to 90
years.

It's not just about the magnitude of the speed vector, it's also the
direction. To match and orbit Pluto, you need that 4.7 km/sec to be _tangent_
to the sun. You need to start out slow enough so that your _radial_ velocity
can fall to zero by the time you get there. You can't apply more radial
velocity to get there faster, either by launch or slingshot, if there isn't
equivalent fuel or mass to decelerate you; you'll overshoot as New Horizons
did.

~~~
burfog
We now have ion thrusters, which are great for when you need a huge velocity
change but can take your sweet time to do it.

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crocal
Anyone else would like to join a trek from Balrog to Cthulhu on a frosty
Plutonian summer day?

~~~
Ididntdothis
You could take a nice swim in a nitrogen lake :)

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Ididntdothis
Does anyone know what shutter speeds and ISO they are using for such pictures?
It must be f...ing dark out there. Or do concepts like shutter speed and ISO
not make sense for the type of camera they are using?

~~~
dr_zoidberg
Shutter speed yes, ISO... I think you can check the gain of the sensor used
for an image, which is a similar concept. You can see this information on the
FITS files ("the raws") metadata.

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api
I love that there is a Cthulhu region, especially given that Pluto is Yuggoth.
:)

