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Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid

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Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid

#81

Post by fspeech »

_Microft wrote: post #30

The above image comes from a 600-kilogram, refrigerator-sized robot travelling at about 15 miles per second, around 170 million miles from Earth. They can be glad that the asteroid is also around 170 million miles from earth, travelling at 15 miles per second and this even in the same direction. Relative motion is smaller though: The gravitational force between the probe (660kg) and asteroid (4.5 * 10^11kg) is just 0…

I assume you calculated the average force and relative velocity experienced in the 450m circular orbit. At the perigee of the polar orbit (when the picture was taken) the force and the relative speed should be bigger. Also due to the small size of the asteroid the gravity should be quite uneven during the approach.

Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid

#82

Post by _Microft »

TylerE wrote: post #80
_Microft wrote: post #30

The above image comes from a 600-kilogram, refrigerator-sized robot travelling at about 15 miles per second, around 170 million miles from Earth. They can be glad that the asteroid is also around 170 million miles from earth, travelling at 15 miles per second and this even in the same direction. Relative motion is smaller though: The gravitational force between the probe (660kg) and asteroid (4.5 * 10^11kg) is just 0…

I'm kinda surprised an orbit that low as been stable for a year. Is this an unusually circular asteroid or is there a fair bit of eccentricity?

The disclaimer was meant to say that it's just an idealized system of two masses at a given distance. I picked these values to show what speed an object orbiting around a 'light' object like an asteroid approximately has.

So sorry: it's not in that orbit. I should have made that clear instead of talking about the probe, circling, ... which sounds pretty concrete.

(The asteroid is not spherical or homogenous and is even supposed to be a "rubble pile" with large holes inside which makes it highly questionable at best to treat it as point mass (you could if the probe were far enough away from it ... which it is not at all), but hey ... ¯\_(ツ)_/¯)

Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid

#83

Post by pdonis »

TylerE wrote: post #80
_Microft wrote: post #30

The above image comes from a 600-kilogram, refrigerator-sized robot travelling at about 15 miles per second, around 170 million miles from Earth. They can be glad that the asteroid is also around 170 million miles from earth, travelling at 15 miles per second and this even in the same direction. Relative motion is smaller though: The gravitational force between the probe (660kg) and asteroid (4.5 * 10^11kg) is just 0…

I'm kinda surprised an orbit that low as been stable for a year. Is this an unusually circular asteroid or is there a fair bit of eccentricity?

The hayabusa spacecraft is not in orbit about the asteroid. It's in orbit about the Sun, in an orbit very, very close to the orbit the asteroid is in, so they stay close to each other for a long time (about a year and a half IIRC).

Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid

#84

Post by dylan-m »

sp332 wrote: post #34
Havoc wrote: post #2

Why are the pictures so fuzzy?

The camera was not a priority for this mission. The small monitor camera was built and installed on the spacecraft thanks to public donations. This mission is about chemical and physical properties of the asteroid. Having a camera on it is mainly for publicity. NASA did a similar thing with the Juno spacecraft, letting people vote on where to point the camera while the main mission was to map out Jupiter's magnetic a…

Indeed, none of these cameras need to be super crisp, although DCAM-3 (the deployable camera) is both a navigational tool and expected to provide some scientific insight. It was used to monitor the impact from the crater they created for the next sample, while Hayabusa 2 was safely on the other side of the asteroid: https://twitter.com/haya2e_jaxa/status/1114112619844005889?l.... That thread also has a shot from one of their navigation cameras, which apparently has a flash.

I love how many deployable objects this spacecraft is carrying, the target markers included. The number of moving parts must be staggering! (I wonder if they charge over USB? :b). JAXA has really amazed me with how resilient their missions have been. (The first Hayabusa limped back with a sample after a bunch of engine failures; their Venus probe failed to enter Venus's orbit, spent 5 years orbiting the sun, then tried again and worked). There's clearly a mountain of potential over there, so it's a treat to see this one go so perfectly smoothly :)

Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid

#85

Post by adrianmonk »

melling wrote: post #76
adrianmonk wrote: post #71

Earlier quoted context omitted.

I estimate the cost to be 1 unit of national pride.

Everything has a cost. NASA estimated their cost was $370 million to switch to metric. https://www.cnbc.com/2015/06/04/why-the-us-hasnt-fully-adopt... The cost of switching road signs alone was quite expensive. Exit numbers, for example, are often the mile marker number.

Oh yeah, I'm not saying there's zero monetary cost. I'm saying the blocker isn't affordability.

Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid

#86

Post by tzakrajs »

Sharlin wrote: post #75
merpnderp wrote: post #49

Earlier quoted context omitted.

I'd assume without an atmosphere to diffuse light, the sun is basically a point light for 95% of the Solar System.

It's a point light infinitely far away. So light rays are parallel, and shadows are exactly the size of the object.

> infinitely

Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid

#87

Post by EdwardDiego »

stallmanite wrote: post #77
EdwardDiego wrote: post #68

Earlier quoted context omitted.

In my country, NZ, we refer to beer as pints, and order them as such, but a pint isn't a legal unit of measurement, so it's accepted that your pint will vary. The good establishments have a chart on the wall explaining how many millilitres map to their "pint". And a pint of high alcohol beer will often be less than a pint of average alcohol beer. 473mL vs 568mL typically. It's not illegal to serve someone a "pint" if…

So at the same establishment you could order two pints of beer and the high ABV one would be smaller in volume? That would really bother me or anyone calculating the unit cost of ethanol.

They make it clear what size they serve it in on their beer menu, so it's not too bad.

Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid

#88

Post by tectonic »

Hayabusa2 is such a cool mission! A veritable space Swiss Army Knife with tantalum bullets, deployable free-floating cameras, four small rovers that hopped around the asteroid in super low-G, and a 1.5kg kinetic impactor that blew a crater.

Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid

#89

Post by zaroth »

tectonic wrote: post #88

Hayabusa2 is such a cool mission! A veritable space Swiss Army Knife with tantalum bullets, deployable free-floating cameras, four small rovers that hopped around the asteroid in super low-G, and a 1.5kg kinetic impactor that blew a crater.

> and a 1.5kg kinetic impactor

TFA called it a cannonball, which is really quite amusing.

Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid

#90

Post by tomrod »

maxxxxx wrote: post #28
jandrese wrote: post #20

Earlier quoted context omitted.

This shot was taken from 9m away. A powerful camera flash would have been sufficient. It fact it seems like a bit of a missed opportunity not to have a handful of powerful but tiny LEDs on the spacecraft and take shots with different lighting to try to get the most detail out of this as possible. Yes you need to be quick, but this can be designed.

As far as I know these things are designed for scientific value and not for producing cool pictures for viewers. I am sure they are getting the best possible value for their budget with whatever they designed.

> not for producing cool pictures for view

Science funding often needs some one's buyin.

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