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Robotic Inchworm Drill for Mars, Europa
Erik Baard writes "
The NY Times (reg. blah) is currently an article on robotic inchworm drills.
NASA is funding Honeybee Robotics' R&D to create an inchworming "underground rover" based in part on a steam pipe welding machine the company built for Con Ed (called the WISER). The autonomous robot (scroll here to the Inchworm Deep Drilling System -- http://www.honeybeerobotics.com/sample.htm) would reach *kilometers* into Mars or Jupiter's moon, Europa, where scientists expect to find liquid water, and just possibly, life. Other drill designs could go perhaps a meter down. The inchworm could either gnaw its way back to the surface, or lay a series of radio relay stations ("bread crumbs") to pass the data signal to an amplifier on the surface to communicate with Earth.
Yeah, I'm a regular /.er. And yeah, the NYT online spelled my name wrong."
When it seems that every other article about NASA is complaining about budget shortfalls for the ISS and how it is limitting its value as a research facility, I find this kind of stuff mildly aggravating. I am happy that my tax dollars are spent on space exploration, but I don't don't see much wisdom behind the way its being handled.
Robotic drills huh? looks like someone has once again "Bullshitted NASA"
I've dirtied my hands writing poetry, for the sake of seduction; that is, for the sake of a useful cause. --Dostoevsky
When you drill through a solid material, you generate "cuttings." Since these cuttingshave voids, their volume is greater than the orginal solid material and must be removed from the bore hole. That's why burying rodents have mounds at the entrance to their holes. How is a robotic inchworm going to remove the cuttings? Will it drag them back out of the hole to the surface? I'm sure that won't be very efficient at depths of several kilometers, because for each few inches it drills, it has to back out to the surface to dispose of the cuttings. That is why robots are not practical for drilling.
What happens if this thing finds an underground cavern? How does it react?
... survive the drop?
1) Does it attempt to backup and go around?
2) Drop into the cavern
3)
4) Get back to the surface?
Humorless sig goes here.
The Earth's crust is only a few kilometres thick, so in principle they could get through to the hot mantle below. The problem is heat and pressure. First, we have no material capable of surviving in such conditions - the robot would be crushed and melted. Second, once you break through into the magma below the solid rock, it would be like popping a champagne cork - instant mini-volcano.
Geothermal power works fine on the temperature difference between the bottom and top of a mineshaft, or running off some volcanic vent like in Iceland, but until we get some really _serious_ material science done there'll be no access to the core itself.
The real purpose of these robots would be to get down through the Martian permafrost or the Europan global glacier to investigate the (warmer? wetter? life-infested??) region below...
Real Daleks don't climb stairs - they level the building.
Can you imagine how easy it would be to lay ethernet cable with these things ? Why if they sold one for, say 200$ it would blow all wireless networks out of the sky, and replace it with something that cannot be interfered with. Cable broken ? Put in a new one, it's only half an hour's work and $5 for 50 meter cable.
..., wires easily maintain a constant data stream of 100 mbit over 150 meters or more, and even gigabit speeds are within reach for consumers right now)
It would also be substantially faster than wireless (10 mbit ? Right
This could truly be the internet for Jack Anonymous. The free and open interconnect for everyone, free (well fixed cost of $5 every 10 years or so)
You have a hell of an imagination ...
1) magma is the SAME material as the earth's crust, which is the same material as a pile of mud in the street. It's just a bit hotter.
2) the would be no "popping" involved. The material above lava is rock under enourmous pressure. Your shaft would collapse on your drill before it would even reach magma and thereby instantly re-"corking" the champagne (not to mention more than probably cutting your drill's power cord)
3) We have a lot of material capable of surviving those conditions, It is a much bigger problem to stabilize the shaft. There have been a LOT of accidents because we were not capable of stabilizing a shaft of 300-800 meters (mine elevators getting crushed etc), we most defineately cannot stabilize a shaft of 10-20 kilometers deep, and don't even dream about a shaft in molten rock
My understanding is that in the (terrestrial) drilling industry, telemetry from the bottom of a borehole is a major problem, with RF being pretty much unworkable -- I assume because of the amount of ferrous material in the borehole itself. Anybody out there who works in oil exploration care to comment?
Roving Web-Teleoperated Robot
The technology is known as Hot Dry Rock geothermal power and has been attempted in a number of places around the World. To the best of my knowledge, there are no commercial plants using the power system.
The first problem is that it doesn't get that hot that quickly under most parts of the World - say about 15 Celsius per kilometre on average. The geothermal gradient in Iceland is upwards of 50 Celsius per kilometre. So if you drilled elseswhere, you'd need a nice deep borehole. Difficult, expensive, but not impractical.
Then you'd need two wells (minimum) of sufficient diameter to accommodate plenty of water. One pipe sends cold water down to the reservoir, the second brings hot water up to the turbines.
Then you'd need to create a sizeable volume of fractured rock to provide a large area for the water to pick up heat. This can be done using hydrofracturing - essentially high pressure water, of course this gets more difficult the further down you go.
This was attempted in the 1980s at Rosemanowes in Cornwall where there were plans to build a geothermal power station using the hot granite as a heat source. A prototype plant had wells sunk to about 2km and the granite fractured. Water was extracted from the system at more than 90 Celsius - too cool for commercial power generation, but a good proof of concept.
The project ran into many problems - including the difficulty of controlling the fracturing process - ideally the fractures should run from one borehole to the other - but quite frequently nature decided not to co operate. The second problem was that the Cornish project lost huge amounts of water through other cracks and fissures - reducing the efficiency of the whole project.
Although the project succeeded in getting very hot water out of the borehole, it was closed down when the government refused to advance any more money for a full commercial plant. A crying shame really as not only would have it produced almost green power, it would have helped employment in a very run-down area. But at the time, the Thatcher government was firmly wedded to the disaster that was the British nuclear programme and was busy killing off any research into alternative power.
I think the main problem would be the economics of such a venture. Even if boring the holes could be made much cheaper, the costs of pumping water and maintaining the plant could make such a scheme impractical for all but the shallowest, hot rocks.
Best wishes,
Mike.