3 ms·
"Gravity on the surface of Ryugu is very weak, so a rover propelled by normal wheels or crawlers would float upwards as soon as it started to move," officials w
by cheeko1234 8y ago
"Gravity on the surface of Ryugu is very weak, so a rover propelled by normal wheels or crawlers would float upwards as soon as it started to move," officials with the Japan Aerospace Exploration Agency (JAXA) wrote in a description of MINERVA-II1A and MINERVA-II1B.
So, the robots — each of which measures 7 inches wide by 2.8 inches tall (18 by 7 centimeters) and weighs 2.4 lbs. (1.1 kilograms) — hop instead. They do this by moving a "torquer" in their interior, which rests atop a disk-shaped turntable.
By rotating the torquer, a reaction force against the asteroid surface makes the rover hop with a significant horizontal velocity," a team of researchers led by JAXA's Tetsuo Yoshimitsu wrote in a 2012 study outlining the concept. "After hopp[ing] into the free space, it moves ballistically. With this mechanism, by changing the magnitude of torque, the hopping speed can be altered, so as not to exceed … the escape velocity from the asteroid surface.
Src: https://www.space.com/41941-hayabusa2-asteroid-rovers-hopping-tech.html https://www.space.com/41941-hayabusa2-asteroid-rovers-hoppin...
- mc32 8y agoWonder if they could use some sort of rather slow mechanical deformation to provide movement with pump mechanisms. I guess that still would rely on significant gravity or other anchoring ti avoid slippage.
- GlenTheMachine 8y agoProblem with that is you're relying on the surface properties of the material you're pushing against. If it's too soft, you get no motion. If it's too hard you get too much. The nice thing about using internal reaction wheels is that the torque you get is entirely independent of the surface you're resting on.
- mc32 8y agoOh those are very observations. Thanks for pointung them out.
- sandworm101 8y agoMovement along the surface via friction (wheels, crawling, snaking etc) is not considered feasible. The surface is probably too loose to provide much traction, but more importantly the low gravity means the vehicle will certainly become caked in dust very quickly. Hopping means you don't disturb the surface, and if you do you probably fly clear of the resulting dust cloud.
- mc32 8y agoMakes sense. Now that yoo bring up dust, how does erosion occur in space, or how would dust form other than perhaps through temperature fluctuations?
- maxxxxx 8y agoI am not an expert but I suppose it gets bombarded by a lot small particles all the time. Over a few million/billion years that adds up.
- sandworm101 8y agoDirty snowball + heat = dirt. Small bits once locked in ice are now dust.
- criddell 8y agoYou don't happen to know of an animation showing the system in action, do you?
- FriedPickles 8y agohttps://youtu.be/b9fITBmQt1Y?t=4m25s https://youtu.be/b9fITBmQt1Y?t=4m25s I recommend watching the whole video.
- criddell 8y agoThat was perfect. Thank you!