Increasing Variety on Pluto's Close Approach Hemisphere and a Dark Pole on Charon | Hacker News Reader

Increasing Variety on Pluto's Close Approach Hemisphere and a Dark Pole on Charon

nasa.gov

113 pointsbenbreen35 comments

This was linked in the article, but should anyone pass over it/not click through, here is a regularly updated list of new pictures from the probe as it gets closer: http://pluto.jhuapl.edu/soc/Pluto-Encounter/index.php

I've been checking in every few weeks and it's been fun to see it slowly getting clearer and larger. I recall watching shows about it on the Science Channel when I was in high school and thinking 9.5 years would be so far away. Feels odd that we're now only a few weeks away from it finally reaching Pluto.

Wow -- the increase in resolution is wild.

1/25: http://pluto.jhuapl.edu/soc/Pluto-Encounter/data/pluto/level...

6/25: http://pluto.jhuapl.edu/soc/Pluto-Encounter/data/pluto/level...

This is so damn cool. It's humbling to realize the scale of the universe we exist in, and how small a part of it we really are. And we're flinging probes around the solar system, millions of miles away, to learn more about our universe.

These are machines that still work, decades after they're launched on top of the most powerful (and most violent) form of transportation we've created, and after they travel millions of miles through the extremes that space provides. It's awe inspiring that we can accomplish things like that, and it's incredibly disappointing that more people don't realize the scale of what is being accomplished.

Speaking of scale, Pluto is more than 2.6 billion miles from Earth at closest approach :).

To put it into context, the closest distance between Earth and Mars is 33.9 million miles, and distance between Earth and Moon is only 238,900 miles.

This checks out. Closest theoretical approaches:

    >>> "%e" % (Pluto.orbit.periapsis - Earth.orbit.apoapsis)
    '4.272109e+12'
    >>> "%e" % (Mars.orbit.periapsis - Earth.orbit.apoapsis)
    '5.455552e+10'
    >>> "%e" % (Moon.orbit.periapsis)
    '3.631042e+08'
    >>> "%e" % Earth.radius
    '6.371000e+06'

Earth-Pluto: 4.27 Tm = 4.27e9 km = 2.65e9 miles

Earth-Mars: 54.6 Gm = 54.6e6 km = 33.9e6 miles

Earth-Moon: 363 Mm = 363e3 km = 226e3 miles

Earth radius: 6.37 Mm = 6.37e3 km = 3.96e3 miles

Heh. s/millions/billions/g

This probe was launched 9 years ago, not decades. I think its speed is even more impressive :-)

> New Horizons was launched on January 19, 2006, from Cape Canaveral, directly into an Earth-and-solar-escape trajectory

I meant that more in the general sense, many of the probes that we have in space have been there for decades. You're right that it is very impressive to have gone so far in so little time!

I like many here find these space probes endlessly fascinating, for several reasons. Of course there's the discovery aspect but what really intrigues me are the engineering challenges and discovering things are huge problems that I never thought of as being problems.

It's an incredible feat to have something like this operate for decades (in the case of Voyager and Pioneer) from both a hardware and software perspective.

But as for eye-opening problems, two examples spring to mind.

Firstly, they don't know exactly where Pluto is. It was only discovered in 1930 and given it has an orbital period of 248 years, we haven't observed it complete even half an orbit yet.

So it's visible to New Horizons but one thing they're not sure of is exactly how far away it is. This is important because in the next week they need to do a final course correction. More:

http://www.nature.com/news/pluto-bound-probe-faces-its-tough...

The second applies to the mission in planning phase to head back to Europa. I knew Jupiter had a strong magnetic field but I didn't realize quite how destructive it's radiation belts were and the source of them is actually Jupiter's magnetic field capturing radiation from the Sun. This is why the mission plans to do flybys rather than orbit Europa.

I think those of us who are software engineers can appreciate this on typically a much smaller scale. Things often look much easier than they actually are until you delve into the details. It's amusing to me to see this apply on much grander scales too.

So it's going to be exciting to images from the flyby of both Pluto and Charon. It's a shame the encounter will be so brief and the resolution of Pluto not super-high (IIRC down to 20km or so) but it'll be a lot more than we have now.

It makes me wonder how complicated an intercept course would've or could be to really study Pluto.

Given our missions to Jupiter and Saturn in the last 20 years I wonder if we'll see a return trip to Uranus or Neptune. I sure hope so.

Even if we don't know exactly where Pluto is, we do know enough about orbital mechanics to have a very good idea of where it will be. Plus, they would run simulations of the solar system to take into account the fluctuations due to gravitational forces of the other planets.

Neptune has only completed one complete orbit since discovery. It was discovered in September 1846 and has an orbital period of 164.8 years. So, it would have completed an orbit in 2011.

You're underestimating the resolution - it's my understanding that we'll be getting a few photos with fractions of a kilometer per pixel during the flyby, if all goes well.

http://www.skyandtelescope.com/astronomy-news/what-new-horiz...

I'd love to see a simulation of particles moving around the Pluto Charon system. I've always wondered how they behave near the barycenter.

Here's some clues about what could cause the variety:

https://blogs.nasa.gov/mission-ames/2013/07/25/playing-marbl...

I've been firmly in the PLUTO IS A PLANET camp my whole life, and the 2006 decision to demote our distant neighbor to planetoid or worse I did not take lightly.

But I have to admit, seeing how tiny the malformed rock is, smaller than the United States, smaller than our own Moon, I have to revise my thinking.

But then . . . Pluto has its own moons! Impossible, but there they are. Five known ones!

This is science at its best. Can't wait for the flyby.

The center of mass of the Pluto / Charon system lies outside of Pluto. So Pluto is more like the larger body in a binary system.

Eris is 27% heavier than Pluto https://en.wikipedia.org/wiki/Eris_(dwarf_planet) . Do you want to classify Eris as a planet too?

It seems hard to say what they're really seeing there - deconvolution to the extent they're doing can be incredibly fickle. You need to know your camera nearly perfectly and have lots of SNR, to start. So it might be more likely that the highly unusual dark region not previously observed is actually a processing artifact.

Very interesting images nevertheless - we'll see how it bears out.

Deconvolution of astronomical images has been studied since the Hubble "astigmatism" incident. That was later corrected with more hardware "up there", but until then deconvolution was the only way to improve the quality of the images. From then on, the technique has been improved, thanks to better math and more processing power available in computers.

It isn't the same as getting closer, but it better resolves details of the image. I think their disclaimer about fine features is sort of a "we're saying this now so nobody screams ALIEN COVERUP at us later" (well maybe not that specifically, but there's always someone that sees one image and interprets it in his own way -- take Ceres Bright Spots for example).

> deconvolution to the extent they're doing

Do you have a link to share for more info on what exactly they're doing? (or even some raw images next to some deconvolved ones?)

Regarding SNR, I believe these images are being sent lossless (whereas the preliminary high-res images we're getting in a few weeks will be lossy for now). Presumably they have a good profile of their camera from before launch too, knowing that they'd have to do this. So I wouldn't be surprised if this analysis does turn out to be accurate. Let's hope!

The 3rd image in the original article compares the original and the deconvolved result.

The main idea is you want to invert a linear transformation (a matrix) which is given by the operation of your imaging system, i.e. a blurring operation. This linear transform often has a poor condition number, however - this means that you can't really invert it, or if you try to you end up with certain components of your signal that need huge amplification, which makes noise sensitivity a major issue.

One solution to this is to introduce a "prior" on your signal that represents your expectations about what the signal looks like, i.e. is it smooth, or does it have a few edges etc. Then you can better tolerate the inherent sensitivities. I'm not sure what priors they're using for this situation or if they're using any at all, so in the absence of such a description I'm taking the results with a grain of salt.

See for example: http://people.seas.harvard.edu/~schan/deconvtv_folder/deconv...

This is such an exiting period! New Horizons about to reach pluto, Dawn about to reach Ceres, and Rosetta orbiting a comet approaching the sun.

Dawn has been orbiting Ceres since March!

Yes, that's right. I was under the impression that it's still getting closer. Exciting nonetheless ;)

Does anybody know any dummies guide to astrophysics that explains how scientists plan out the journey of the spacecraft with incredible precision?

The orbital mechanics math is fairly well understood so we know when planets will be in specific locations so it works out to be a more complex version of an orbital transfer.

http://www.bogan.ca/orbits/transfer/Earth2Mars.html

The key things is that they use gravity assists from planets to cause the probe to speed up or slow down. JPL has a good primer, webcast, and simulator on the topic.

http://www2.jpl.nasa.gov/basics/grav/primer.php

The gravity assists are the tricky part. In JPL's "Basics of Space Flight", there's a discussion of the Voyager 2 trajectory,

http://www2.jpl.nasa.gov/basics/bsf4-1.php

If you'd like to try learning by doing, sort of, the 2009 ICFP Contest had you write code to control a spacecraft performing several tasks: http://www.ittc.ku.edu/icfp-contest/

I enjoyed it, though I don't think I got past the first couple of missions. Can anyone recommend another game? There's Kerbal Space Program, which I haven't tried but was said to stick to Kepler orbits, not like the numerically-integrated gravity of the above simulation.

KSP is really good for exploring gravity assists, actually – they work just the same way in the Keplerian 'patched conics' approximation as in real life. For Newtonian physics, there's Orbiter, which is much more of a simulation than a game; it puts you in our own Solar System, for one thing.

http://orbit.medphys.ucl.ac.uk/

Neat, thanks!

you are correct that ksp orbits are kepler, no playing with things like lagrange points.

with that said you can do some cool stuff, especially when you get into exploring the available mods. kOS might be of interest to you - it adds the ability to write programs to control your creations.

I hadn't heard of kOS -- thank you.

I believe they also have 2 or 3 "correction" fires of the engines in every trip. They know of their exact position by looking at the planets and radio waves.

I remember reading somewhere that the Curiosity mars ship initial impulse was so perfect that there was no need of additional corrections.

So NASA can send a probe to Pluto, but can not show pictures and text without resorting to Java Script. I believe this conclusively proves that HTML is not rocket science.

Wow, the most amazing space venture in a very long time, over 9 years in waiting, and you complain about JavaScript? I'm sorry, but I just don't understand. I wouldn't care if the images were delivered to my house as a deck of punched cards!

I don't think it's possible for a thread to exist on hacker news without somebody complaining about how the web page renders.

Yes, it is amazing. However, it is quite annoying to have to switch on js just to view the site. ( Actually it would be kind of cool to get it as a deck of punch cards. )

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