I just want to go 15 miles per second (54000 mph/86904.6 Kph/46925 knt).
Does knots even make sense outside of the context of being located on a sphere?
Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
21–30 of 98 posts
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#22It bothers me (too much) that we are going to space and still using 'feet' as a unit of measurement.
We don't use the imperial system for space, but the American readers do.
https://www.space.com/3332-nasa-finally-metric.html
I'm just as guilty as the next person when I post numbers. Occasionally, I'll also show metric. However, as an old(er) dog, my first instinct is to use feet, miles, etc.
Perhaps we should agree to use only the metric system on HN?
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#23It bothers me (too much) that we are going to space and still using 'feet' as a unit of measurement.
At least it wasn't...
Japan's Hayabusa2 spacecraft grabs close-up 1/10th of an American football field above asteroid
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#24Why are the pictures so fuzzy?
Insane Contrast ratio - ultra bright sunlight when the sun gets in the frame (no atmosphere to diffuse light) plus ultra dark hard shadows as the light source is millions of miles away, and again no atmosphere to diffuse the light. Again ultra dark, so the camera needs to have an incredibly sensitive sensor. And incredible motion, the spacecraft is whipping by the asteroid quickly.. so you'd need a fast shutter speed…
I’m surprised they didn’t house a mirror on the craft to aid in illumination
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#25It bothers me (too much) that we are going to space and still using 'feet' as a unit of measurement.
You should be happy that they don’t measure it in “baseball fields” or something like that. That’s how usually things are reported.
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#26Why are the pictures so fuzzy?
Insane Contrast ratio - ultra bright sunlight when the sun gets in the frame (no atmosphere to diffuse light) plus ultra dark hard shadows as the light source is millions of miles away, and again no atmosphere to diffuse the light. Again ultra dark, so the camera needs to have an incredibly sensitive sensor. And incredible motion, the spacecraft is whipping by the asteroid quickly.. so you'd need a fast shutter speed…
> And incredible motion, the spacecraft is whipping by the asteroid quickly
No it's not. The whole point of the Hayabusa2 mission is to go to the asteroid and stay there. In fact it landed on it and grabbed a sample back in March.
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#27I just want to go 15 miles per second (54000 mph/86904.6 Kph/46925 knt).
Does knots even make sense outside of the context of being located on a sphere?
According to https://en.wikipedia.org/wiki/Nautical_mile, nautical mile used to be defined as 1/60 of a degree of latitude, but is now defined as exactly 1852 metres. So feasible to use even in space, although unusual.
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#28Earlier quoted context omitted.
> no atmosphere to diffuse light Could the spacecraft—just in theory— introduce an atmosphere? Maybe not this spacecraft, but if we’re riding around in the starship Enterprise and want to get better snaps of asteroids, would it be a good idea to just send out a big pair of glass hemispheres, encapsulate the asteroid with them, pump them full of air, and then take a picture of the asteroid-capsule system? Alternately,…
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.
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#2930 feet = ~9.14 meters
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#30The 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 0.1 N. The probe has therefore to be circling the asteroid with about 0.25m/s or just 1km/h (0.57 mph for american readers).
And how else could it be: the asteroid was assumed to be a point mass and the probe in a circular orbit of 450m around it.