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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."
Here
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.
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.
track7.org has all kinds of interesting stuff!
The problem with melting is that it takes a LOT of energy. The surface of Europa is 130K (-143C, -225F). That means to need to heat the Ice to 0C, then supply enough energy to melt it...
Keep in mind that the rest of the ice in the area is still going to be at -143C. (or very near -143C, if it's immediately adjactent to the driller) So you have to supply enough heat to make up for conduction losses in order to raise the temperature.
As a home experiment, try piercing an ice cube with a soldering iron. Takes longer than you thought, doesn't it? Now imagine the ice cube to be the size of the moon, and the temperature of the ice and surrounding air was come 170 degrees colder.
The heat generated from the friction of cutting blades would be absolutely negligable at -143C.
As another home experiment, try drilling through an ice cube. It's not going to melt all that much (if at all). Now imagine the ice cube to be the size of the moon, and the temperature of the ice and surrounding air was come 170 degrees colder.
Melting may be 'simpler' in that it mas no moving parts, but drilling is by far more practical.
Anyone care to offer an estimation on the dimentions of the probe? I'll gladly work out the actual power required to melt the ice and maintain a liquid barrier around it at these temperatures.
=Smidge=
Yeah, because drilling tunnels randomly between two points is childs play. I mean, what could go wrong? Not like anything else is buried underground....
And who cares if the 10$-15k rental equipment gets stuck under some highway. You can always shut down traffic, bring in the back hoe, break open the pavement, cart of 1/2 ton of concrete and asphalt, and retrieve the device...
The search and retrieve operation would only cost 300k or so.
Man, what world do you people live in? Have you ever tried to get trench permits from a city? And you think arbitrary tunnels will be looked more favorable on?
The EM spectrum is natures peace offering to us to stop fucking drilling holes in her. Lets get some FCC reform, turn the entire spectrum into a shared spectrum with frequency hoping recievers and auto-relays/routers in each consumer device, and use the nearly inifinte amount of bandwidth that electricity and magnetism provide us.
-malakai
-Malakai
A Dragon Lives in my Garage
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.