"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.
Wonder 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.
I love that they opted for color cameras. Not much color to be seen, but the flares, together with the motion blur (while falling and hopping!) make the pictures look really dynamic. :)
I'm not entirely sure that's motion blur. The images shown in the article make it look like it's just lens distortion. It's probably a fairly wide angle lens, and that's why things look stretched out the further from the center of the image they are. (I think.)
Wonder if it's because they were planning on taking pictures while hopping? The usual one-picture-per-color-filter method that they usually use on space probes probably wouldn't work well while in relatively fast motion.
Just came back from Europe. Everyone knows about this and all media reported on it. Surprisingly so little is said in American media. Its not new that Americans do not like other nations succeed in space! If these were US-based rovers, each network will give it 10 minutes cover. Same sad story about Chinese Moon landing. Most American friends laughed at me when I told them China landed rover on moon. Some even question Wiki article as conspiracy theory.
Consider literal competitions--it was similarly appalling to watch recent Olympics in the US. 95% or more of the coverage was of Americans winning. If a particular day had fewer wins, they would replay earlier footage rather than dare show any other country succeeding at non-American dominant areas. One saving grace is that the NBC app had all the footage they didn't deem worthy of broadcasting.
It's a big problem in the US that other countries only get acknowledged as in relation to the US. In a way this myopia serves the country pretty well and it's big enough to do most things themselves. But sometimes interesting things that happen in other countries get overlooked and nothing is learned.
>> Some even question Wiki article as conspiracy theory.
Is there a Wikipedia page that "some" Americans don't think is a conspiracy? Conspiracies used to be about aliens and secret research programs in bunkers. Now they are about pizza restaurants. I gave a presentation at an Airforce base where a flat-earther accused me of participating in the conspiracy. I wanted to throw him out as a dangerous or unstable person, or strap him to the underside of a plane and show him the curve in person.
These days, every article, every statement, has to address the 5-10% of people who just don't believe anything anyone tells them.
I am waiting for one of the "airplanes run on compress air" conspiracy people. (It's the latest version of chemtrails.) We'll have them fill a few aircraft by hand... with buckets.
Considering their very tiny size, I'm curious about three things... What sort of software/watchdog timer these mini rovers have set up for charging their batteries, the size and type of the batteries (in Wh, chemistry, etc), and how often they wake up and take photos and temperature measurements.
The size of the surface area exposed to the sun with high-efficiency PV cells is not very large, since they are so tiny. I'm assuming the cells are triple-junction GaAs for the greatest Wh per square cm per day.
Less gravity, more radiation/light. There is lots of water/ice involved, and the rock varies in distance from the sun. So the layered effect is probably the result of different temperatures at various depths, and the resulting sublimation (or not) of water ice. Imho it is akin to the layered effect in soil during a hard frost.
Stupid question: why does these images look so low res and over/under exposed. Sometime I feel iPhone camera tend to do much better job than those million dollar cameras on these missions. I am obviously missing some key details.
One of my personal wishes is that we covered as much surface area of asteroids and other interesting bodies in the solar system; one wonders, if we sample enough, what unexpected things we will find?
They have an open websocket to an Asteroid Landing five-layer Neural Network. The lander sends images back in real time and the earth-borne NN sends it telemetry adjustments in BSON.
Diamonds are unlikely to be found on asteroids, because they require immense pressures to form, and the gravity on asteroids is so weak that even at the core the pressure is less than sea level air pressure on Earth.
Hayabusa2 carries multiple science payloads for remote sensing, sampling, and four small rovers that will investigate the asteroid surface by hopping and then on top of all that it will bring back samples in 2020!
All of that for less than $150 million! From a research data point of view, even having a color camera was overkill. Reminds me of Carl Sagan having to convince NASA to take the pale blue dot picture since it doesn’t have any significant value in the field of astronomy.
I'm pretty sure it's not a poor camera because they couldn't afford it. It'll be because of weight considerations. If you have a higher resolution camera, everything has to be bigger and heavier - larger camera, more local storage, more processing power, bigger antenna (these have to be sent using lossless compression for science), etc. Each robot has a mass of 1.1 kg, lighter than my laptop - and it has to do other science and return a sample to earth!
[+] [-] cheeko1234|7 years ago|reply
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-hoppin...
[+] [-] criddell|7 years ago|reply
[+] [-] mc32|7 years ago|reply
[+] [-] black_puppydog|7 years ago|reply
[+] [-] joemi|7 years ago|reply
[+] [-] magicalhippo|7 years ago|reply
[+] [-] java-man|7 years ago|reply
[+] [-] chuckledog|7 years ago|reply
I really admire that its means of propulsion doesn’t involve wheels (since the gravity is so low)
[+] [-] joering2|7 years ago|reply
[+] [-] z2|7 years ago|reply
[+] [-] Gravityloss|7 years ago|reply
Really good photos and videos and web pages and TV material. Lenient sharing licenses etc.
[+] [-] maxxxxx|7 years ago|reply
[+] [-] sandworm101|7 years ago|reply
Is there a Wikipedia page that "some" Americans don't think is a conspiracy? Conspiracies used to be about aliens and secret research programs in bunkers. Now they are about pizza restaurants. I gave a presentation at an Airforce base where a flat-earther accused me of participating in the conspiracy. I wanted to throw him out as a dangerous or unstable person, or strap him to the underside of a plane and show him the curve in person. These days, every article, every statement, has to address the 5-10% of people who just don't believe anything anyone tells them.
I am waiting for one of the "airplanes run on compress air" conspiracy people. (It's the latest version of chemtrails.) We'll have them fill a few aircraft by hand... with buckets.
[+] [-] cheeko1234|7 years ago|reply
[+] [-] coldtea|7 years ago|reply
[+] [-] tychomaz|7 years ago|reply
[+] [-] walrus01|7 years ago|reply
The size of the surface area exposed to the sun with high-efficiency PV cells is not very large, since they are so tiny. I'm assuming the cells are triple-junction GaAs for the greatest Wh per square cm per day.
[+] [-] tychomaz|7 years ago|reply
[+] [-] JoeAltmaier|7 years ago|reply
[+] [-] sandworm101|7 years ago|reply
[+] [-] sytelus|7 years ago|reply
[+] [-] dekhn|7 years ago|reply
[+] [-] yazr|7 years ago|reply
Is it at all possible to match the spin of a smallish android from orbit ?
[+] [-] tychomaz|7 years ago|reply
[+] [-] ceejayoz|7 years ago|reply
https://spaceflightnow.com/2018/06/20/asteroid-ryugu-reveale... says Ryugu only rotates once every 7.6 hours.
[+] [-] gchokov|7 years ago|reply
[+] [-] skykooler|7 years ago|reply
[+] [-] rhcom2|7 years ago|reply
[+] [-] hmmm_yah|7 years ago|reply
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[+] [-] 21|7 years ago|reply
I am a bit shocked at the potatoness of it.
[+] [-] cheeko1234|7 years ago|reply
All of that for less than $150 million! From a research data point of view, even having a color camera was overkill. Reminds me of Carl Sagan having to convince NASA to take the pale blue dot picture since it doesn’t have any significant value in the field of astronomy.
[+] [-] rwmj|7 years ago|reply