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Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
91–98 of 98 posts
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#92Hayabusa2 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.
You seem knowledgeable: what is a target marker, and how was it used?
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#93Earlier quoted context omitted.
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).
I couldn't find any information on the trajectory. The sphere of influence in which the gravitational attraction of the asteroid dominates over that of the sun has a radius of about 6km though. So as long as the probe moves inside this area, it has to orbit or spend fuel of the reaction control system (the ion thrusters are inactive in the vicinity of the asteroid, they'd also have only enough thrust to allow hovering in a distance of hundreds of meters (in the tens of milli-newtons)).
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#94Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#95Earlier quoted context omitted.
Who's "we"? This article is about Japan. The Japanese do not ever use "feet" as a unit of measurement. It's only Americans who still use feet and other imperial units, which is why they lost a Mars probe.
Calm down. I clearly understood that as we humans, a collective whole.
Humans, in general, do not use "feet" for measurement. It's only dumb Americans. They don't represent humanity: they're only a small fraction of all humans (around 4%). Don't blame humanity for something that only Americans do.
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#96Earlier quoted context omitted.
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).
I couldn't find any information on the trajectory. The sphere of influence in which the gravitational attraction of the asteroid dominates over that of the sun has a radius of about 6km though. So as long as the probe moves inside this area, it has to orbit or spend fuel of the reaction control system (the ion thrusters are inactive in the vicinity of the asteroid, they'd also have only enough thrust to allow hoverin…
> The sphere of influence in which the gravitational attraction of the asteroid dominates over that of the sun has a radius of about 6km though.
It depends on what you consider "dominates" to mean. For example, the corresponding value for the Earth and the Sun is 924,000 km, and the Moon is only 400,000 km from the Earth, but the Moon's orbit is still always concave towards the Sun.
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#97Earlier quoted context omitted.
I couldn't find any information on the trajectory. The sphere of influence in which the gravitational attraction of the asteroid dominates over that of the sun has a radius of about 6km though. So as long as the probe moves inside this area, it has to orbit or spend fuel of the reaction control system (the ion thrusters are inactive in the vicinity of the asteroid, they'd also have only enough thrust to allow hoverin…
> The sphere of influence in which the gravitational attraction of the asteroid dominates over that of the sun has a radius of about 6km though. It depends on what you consider "dominates" to mean. For example, the corresponding value for the Earth and the Sun is 924,000 km, and the Moon is only 400,000 km from the Earth, but the Moon's orbit is still always concave towards the Sun.
I'm not sure what you mean?
If Earth wouldn't dominate the space in which the Moon moves, the Moon wouldn't be in orbit around Earth at all and the Sun couldn't perturbe this orbit (as you even stated yourself)?
Re: Japan’s Hayabusa2 spacecraft grabs close-up thirty feet above asteroid
#98Earlier quoted context omitted.
> The sphere of influence in which the gravitational attraction of the asteroid dominates over that of the sun has a radius of about 6km though. It depends on what you consider "dominates" to mean. For example, the corresponding value for the Earth and the Sun is 924,000 km, and the Moon is only 400,000 km from the Earth, but the Moon's orbit is still always concave towards the Sun.
I'm not sure what you mean? If Earth wouldn't dominate the space in which the Moon moves, the Moon wouldn't be in orbit around Earth at all and the Sun couldn't perturbe this orbit (as you even stated yourself)?
> If Earth wouldn't dominate the space in which the Moon moves
My point is that "dominate" here could mean different things, and the Earth does not dominate all of them.
Specifically, the fact that the Moon's orbit is always concave to the Sun means that the "acceleration due to gravity" of the Sun on the Moon is larger than the "acceleration due to gravity" of the Earth on the Moon. In other words, the net "acceleration due to gravity" of the Moon is always towards the Sun, not towards the Earth. So the Earth does not dominate in this way.
The "sphere of influence" you mention is based on tidal forces: the tidal effect of the Earth on the Moon is larger than the tidal effect of the Sun on the Moon. So the Earth does dominate in this way.
> the Moon wouldn't be in orbit around Earth at all and the Sun couldn't perturbe this orbit (as you even stated yourself)?
No, that's not what I said. Whether you think of the Moon as orbiting the Earth or the Sun depends on how you define "orbit" and what you are trying to do. If you define "orbit" according to which body the Moon is accelerating towards, on net, then the Moon is orbiting the Sun, not the Earth (see above); in this sense, the Moon and the Earth are in two closely matched orbits about the Sun.
And my point about the Hayabusa spacecraft and the asteroid is that, if you calculate the "acceleration due to gravity", you find that it's similar to the Moon's--the spacecraft's net acceleration is towards the Sun, not towards the asteroid.