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New Horizons’ first hi-res imagery of Ultima Thule

pluto.jhuapl.edu

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Re: New Horizons’ first hi-res imagery of Ultima Thule

#41

Post by tabtab »

mbrundle wrote: post #2

I find it truly amazing that New Horizons was able to take photos of a 20 mile object whilst flying past at ~8 miles/sec - that’s an incredibly small space and time window within which to capture the images. Does anyone know how NASA manages to pilot spacecraft with this level of precision? What kind of engineering processes do you need to enable this?

Re: able to take photos of a 20 mile object whilst flying past at ~8 miles/sec...Does anyone know how NASA manages to pilot spacecraft with this level of precision?

I cannot speak for this probe, but other probes have made the probe itself or camera boom move slightly to compensate for the target moving relative to the probe. It's kind of like moving your head back and forth to follow a tennis match if your eyes alone have difficulty tracking.

The object looks like BB-8. We'll get even better pics in the coming weeks.

Re: New Horizons’ first hi-res imagery of Ultima Thule

#43

Post by dwaltrip »

jdmichal wrote: post #35
lisper wrote: post #33

Earlier quoted context omitted.

> photos of a 20 mile object whilst flying past at ~8 miles/sec Not to detract at all from the astonishing technical achievement, but that's the wrong comparison. You can see the ISS with your naked eye, and it's a Actually, the right comparison is of the closest approach distance (~2000 miles) with the distance from earth (4,000,000,000 miles). That's like launching a missile from Los Angeles to New York and hitting…

To be fair, while that's an accurate representation of the distances, it's not accurate of the difficulty. They don't have to deal with unpredictable atmosphere. There's reasons laser-guided missiles are about 1-2 meters-ish of accuracy with constant guidance, while we can basically fire-and-forget spacecraft to 4 billion miles away.

They do have to deal with accurately determining the target destination, especially so in this case.

Re: New Horizons’ first hi-res imagery of Ultima Thule

#44

Post by lisper »

jdmichal wrote: post #35
lisper wrote: post #33

Earlier quoted context omitted.

> photos of a 20 mile object whilst flying past at ~8 miles/sec Not to detract at all from the astonishing technical achievement, but that's the wrong comparison. You can see the ISS with your naked eye, and it's a Actually, the right comparison is of the closest approach distance (~2000 miles) with the distance from earth (4,000,000,000 miles). That's like launching a missile from Los Angeles to New York and hitting…

To be fair, while that's an accurate representation of the distances, it's not accurate of the difficulty. They don't have to deal with unpredictable atmosphere. There's reasons laser-guided missiles are about 1-2 meters-ish of accuracy with constant guidance, while we can basically fire-and-forget spacecraft to 4 billion miles away.

No, that's actually not true. Hitting Ultima-Thule is much harder. For starters, just figuring out where U-T actually is is very difficult. The observations we have only constrain two of its three degrees of orbital freedom. The third has to be inferred via orbital mechanics. Likewise, figuring out where the spacecraft is is also non-trivial. By way of contrast, figuring out where you are relative to New York to within a meter of accuracy is, nowadays, a simple matter of switching on your GPS receiver. (Even without GPS, all you need is inertial guidance that is stable for half an hour or so. That's much easier to achieve.)

Finally, there are unpredictable orbital disturbances. N-H uses thrusters for attitude control, whose effect on the trajectory is not entirely predictable. (c.f. https://en.wikipedia.org/wiki/Pioneer_anomaly, which was only detectable because, although Pioneer had thrusters, they were turned off for long periods of time).

I know these things because I used to work at JPL. There are entire teams dedicated to spacecraft navigation. The stuff they do will blow your mind.

Re: New Horizons’ first hi-res imagery of Ultima Thule

#45

Post by weavie »

jameskilton wrote: post #5
mbrundle wrote: post #2

I find it truly amazing that New Horizons was able to take photos of a 20 mile object whilst flying past at ~8 miles/sec - that’s an incredibly small space and time window within which to capture the images. Does anyone know how NASA manages to pilot spacecraft with this level of precision? What kind of engineering processes do you need to enable this?

Actually doing the fly-by is less impressive (the fly-by was planned and programmed a while ago) than the fact that we were able to line up Horizons to an object like this at all! https://twitter.com/Alex_Parker/status/1077986070128668674

I find it more impressive and awe inspiring that stuff in space is so predictable that we can actually program the fly by such a long time in advance and get such a high degree of accuracy.

Re: New Horizons’ first hi-res imagery of Ultima Thule

#46

Post by zabzonk »

hughes wrote: post #22
robotrout wrote: post #19

Earlier quoted context omitted.

So, two masses were close enough in relative velocity and vector, that one of them didn't careen off the other one, and instead, allowed the weakest of all known forces to bond them together as they hurtled at high velocity through space. This object(s) seem statistically unlikely to me. I'm not saying it's artificial. That would be even more unlikely, by orders of magnitude. Just saying "Wow!".

As this is the first Kuiper Belt Object we've visited, it's hard to draw much about the statistics of the thing.

The second, actually - Pluto is generally recgnised a Kuiper Belt object.

Re: New Horizons’ first hi-res imagery of Ultima Thule

#47

Post by compsciphd »

skunkworker wrote: post #10

That is amazing. It reminds me of a snowman or two snowballs frozen together, except it's red not white. As seen in the combined image. http://pluto.jhuapl.edu/Galleries/Featured-Images/pics800wid...

my caption to the article that I posted to facebook was "do you wanna build a snowman", so I guess thinking along the same lines :)

Re: New Horizons’ first hi-res imagery of Ultima Thule

#48

Post by dnautics »

weavie wrote: post #45
jameskilton wrote: post #5

Earlier quoted context omitted.

Actually doing the fly-by is less impressive (the fly-by was planned and programmed a while ago) than the fact that we were able to line up Horizons to an object like this at all! https://twitter.com/Alex_Parker/status/1077986070128668674

I find it more impressive and awe inspiring that stuff in space is so predictable that we can actually program the fly by such a long time in advance and get such a high degree of accuracy.

have you ever done course corrections in KSP? A tiny nudge early on is enough to make a huge difference farther out!

Re: New Horizons’ first hi-res imagery of Ultima Thule

#49

Post by tabtab »

hughes wrote: post #22
robotrout wrote: post #19

Earlier quoted context omitted.

So, two masses were close enough in relative velocity and vector, that one of them didn't careen off the other one, and instead, allowed the weakest of all known forces to bond them together as they hurtled at high velocity through space. This object(s) seem statistically unlikely to me. I'm not saying it's artificial. That would be even more unlikely, by orders of magnitude. Just saying "Wow!".

As this is the first Kuiper Belt Object we've visited, it's hard to draw much about the statistics of the thing.

Re: first Kuiper Belt Object we've visited

Pluto may be a KBO also. Further, it's possible some moons of the gas-giant planets are captured KBO's.

The unusual thing about Ultima Thule is that it's in a nearly circular and "flat" orbit, which many experts interpret to mean it's mostly undisturbed from its point of origin. It's a prime "fossil".

Pluto has a "disturbed" orbit such that its origin is currently unknown. Same for gas-giant moons. Pluto has also been turned inside-out, perhaps multiple times, by a still unidentified force. Ultima Thule is probably mostly as-is since formation.

Re: New Horizons’ first hi-res imagery of Ultima Thule

#50

Post by stcredzero »

skunkworker wrote: post #10

That is amazing. It reminds me of a snowman or two snowballs frozen together, except it's red not white. As seen in the combined image. http://pluto.jhuapl.edu/Galleries/Featured-Images/pics800wid...

It reminds me of a snowman or two snowballs frozen together, except it's red not white.

The 21st century world of asteroid and Kuiper belt colonization is going to be far fluffier and squishier than we thought it would be in 80's Sci-fi!

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