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Japan's zero-gravity space drone sends first pictures from ISS

bbc.com

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Re: Japan's zero-gravity space drone sends first pictures from ISS

#51

Post by mistercow »

e12e wrote: post #50
lawless123 wrote: post #46

Earlier quoted context omitted.

>I'm assuming if you do that precisely enough (and in three dimensions), you can generate linear movement. You can rotate it. You wouldn't be able push it around that way though.. if you manged that it would be a reactionless drive..

What if the wheels aren't centered? You could probably not get linear movement - but couldn't you rotate around a point other than the center? ..a...b.. Rotate ~180 degrees around a, then b? [ed: from other comments I see I may be too used to thinking in a gravity constrained environment..?]

I'm not positive, but I'm pretty sure wherever you put the wheels, you aren't going to get the drone to rotate about any point other than its center of mass.

Re: Japan's zero-gravity space drone sends first pictures from ISS

#52

Post by noonespecial »

spthorn60 wrote: post #38

Why is the astronaut wearing a belt?

If you put a fabric covering on any flexible structure and then flex it, the fabric has a tendency to gather at the joints. I'm surprised he has not elastic straps on his ankles as well as I'b bet without the usual forces in play I would think his pants would ride up his calves towards his knees as well.

There is an entire community of people however who collect "evidence" that the ISS is a hoax! This would be exactly the kind of "proof" they'd love!

Re: Japan's zero-gravity space drone sends first pictures from ISS

#54

Post by e12e »

mistercow wrote: post #51
e12e wrote: post #50

Earlier quoted context omitted.

What if the wheels aren't centered? You could probably not get linear movement - but couldn't you rotate around a point other than the center? ..a...b.. Rotate ~180 degrees around a, then b? [ed: from other comments I see I may be too used to thinking in a gravity constrained environment..?]

I'm not positive, but I'm pretty sure wherever you put the wheels, you aren't going to get the drone to rotate about any point other than its center of mass.

Makes sense, when thinking of it like a force - any where you push at the exterior (or interior) that's not directly at the center, would cause rotation around the center. I gather internal forces would add up/cancel out and never end up in a vector that pushes on the center of mass.

Re: Japan's zero-gravity space drone sends first pictures from ISS

#55

Post by frandroid »

DougWebb wrote: post #32
TeMPOraL wrote: post #4

Earlier quoted context omitted.

It seems to be rotating via reaction wheels (via this[0]). I haven't yet figured out how it translates, though. EDIT: if you have gravity available, the video on that site illustrates a clever way to use those reaction wheels to move around by tumbling. EDIT2: "for maneuvering around in space there are twelve electric micro-fans or μFans"[1]. The SE thread has a screenshot of a video which shows the placement of thos…

The use of fans is disappointing; that means it can't go outside. My first thought when seeing it is that it'd be great for doing external inspections, and could even have its own private little airlock to get in and out. Maybe they could make a version with ionic thrusters, that stays outside all of the time. It could have a 'nest' where it parks and refuels when not in use.

You could just set rails or clotheslines outside the station for an external drone camera to travel along.

Re: Japan's zero-gravity space drone sends first pictures from ISS

#56

Post by munificent »

TeMPOraL wrote: post #4
gcb0 wrote: post #2

and no word on how it moves. even bbc is going downhill :(

It seems to be rotating via reaction wheels (via this[0]). I haven't yet figured out how it translates, though. EDIT: if you have gravity available, the video on that site illustrates a clever way to use those reaction wheels to move around by tumbling. EDIT2: "for maneuvering around in space there are twelve electric micro-fans or μFans"[1]. The SE thread has a screenshot of a video which shows the placement of thos…

Here's a video that shows the actual thing moving in zero gravity:

https://www.youtube.com/watch?v=PntNBeJuRFQ

Re: Japan's zero-gravity space drone sends first pictures from ISS

#57

Post by hoorayimhelping »

DougWebb wrote: post #32
TeMPOraL wrote: post #4

Earlier quoted context omitted.

It seems to be rotating via reaction wheels (via this[0]). I haven't yet figured out how it translates, though. EDIT: if you have gravity available, the video on that site illustrates a clever way to use those reaction wheels to move around by tumbling. EDIT2: "for maneuvering around in space there are twelve electric micro-fans or μFans"[1]. The SE thread has a screenshot of a video which shows the placement of thos…

The use of fans is disappointing; that means it can't go outside. My first thought when seeing it is that it'd be great for doing external inspections, and could even have its own private little airlock to get in and out. Maybe they could make a version with ionic thrusters, that stays outside all of the time. It could have a 'nest' where it parks and refuels when not in use.

I'm sure there are very strict rules about having anything flammable or explosive on board ISS, which pretty much means you can't have a drone that can move under its on propulsion both inside and outside the station.

Re: Japan's zero-gravity space drone sends first pictures from ISS

#58

Post by Sharlin »

bostonpete wrote: post #35
jamesvandyne wrote: post #23

Earlier quoted context omitted.

They'll should still have plenty of time for taking photos. Astronauts usually work a regular 8-ish hour work day up in the ISS and have weekends etc... 2 of those working hours each day are blocked out for exercise, too, so this should be a real boon.

They work 8 hours a day including exercise? That seems bizarre to me. I know we don't want them burning out, etc., but if we're sending astronauts up there at great expense I'd think we'd want to ask them to put in a little more than 8 hour days. 16 hours a day plus weekends seems like a ridiculous amount of free time given that there's no commuting, family time (other than calls), yard work, social engagements, etc.

I don't think they actually work just eight hours a day. There's a lot of maintenance work to do and it's not like there are many things to do on your free time. Although now that there's the full six-person crew, the schedules are probably less tight.

Re: Japan's zero-gravity space drone sends first pictures from ISS

#59

Post by hoorayimhelping »

bostonpete wrote: post #35
jamesvandyne wrote: post #23

Earlier quoted context omitted.

They'll should still have plenty of time for taking photos. Astronauts usually work a regular 8-ish hour work day up in the ISS and have weekends etc... 2 of those working hours each day are blocked out for exercise, too, so this should be a real boon.

They work 8 hours a day including exercise? That seems bizarre to me. I know we don't want them burning out, etc., but if we're sending astronauts up there at great expense I'd think we'd want to ask them to put in a little more than 8 hour days. 16 hours a day plus weekends seems like a ridiculous amount of free time given that there's no commuting, family time (other than calls), yard work, social engagements, etc.

I think you might be grossly underestimating the psychological impact of spending 6 months inside a place the size of an apartment with no day or night cycle, a constant feeling of weightlessness, and no ability to go outside or feel things like wind or rain.

Re: Japan's zero-gravity space drone sends first pictures from ISS

#60

Post by Retric »

eeZah7Ux wrote: post #49
Retric wrote: post #29

Earlier quoted context omitted.

Precision and speed, reaction wheels can go from start, rotate you one degree and then stop all motion. With fans your going to end up constantly correcting because you never hit zero rotation.

The robot is exposed to the station airflow so it has to adjust constantly anyways.

While non zero, the spherical shape and minimal ISS airflow generally makes this a non issue. You can use those reaction wheels to calibrate very precise adjustments over time, you can also just bump into something to get rid of excess rotation.

Note, space telescopes effectively use both approaches.

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