... drilling through the dance floor
Oh man, look at that lander go
It's the freakiest show....
NASA's Mars InSight lander is due to arrive on the Red Planet on Monday, giving scientists their first in-depth look at the martian interior. The Lander InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is based on 2008's Phoenix Lander, which itself used components left over from the …
Any info out there on how the HP3 'mole' is designed to work?
A small, unguided pipe mole on Earth can hit a stone and reappear at the surface only a few inches away. They're aiming for 15m deep dragging a cable through the spoil-filled hole which, in my experience, would start jamming the cable severely and very quickly making the process at best difficult and at worst stretch and break the data/power cable after 50cm ...
Need geeky mechanical info ...
The mole works like a jack hammer. Basically inside you have a spring loaded cam that gets loaded up and then releases with a sharp shock that drives the Mole down. The rebound is much slower and is damped by the soil friction along the sides of the Mole (the Mole is long and thin for that reason). This basically means that each stroke down embeds you that little bit further into the soil.
It also means that how fast it is, is highly dependant on what the soil is like. I was one of the designers of the Mole, and believe me we spent ages testing in lots of different soils. The Mole is also powerful enough to scrape along concrete blocks provided it doesn't hit dead on.
As for the cable, it's a special type of electrical flat cable, similar to Kapton tape. Very slippy and it has the added job of collapsing the tunnel afterwards - the cable carries a series of heat sensors which we need in contact with the soil, hence why we do that.
Whilst we did as much testing as possible over the last few years, in vacuum Chambers, in different soils, with rocks and the like buried in the soil, its still impossible to know for certain it will work as planned. Mainly because we have no idea what the Martian soil is actually like. To give an analogy, imagine your are asked to drill a hole in a wall, but your only info about the wall is a picture of the wall with a resolution of 1 pixel per 0.5m^2. What drill bit do you take? A masonry bit because most walls in houses are masonry? What if it happens to be steel or wood? What feeds and speeds do you run the drill at? That's basically what we're dealing with with insight
- attempting the difficult in the face of the unknown - fingers crossed!
It is pulsed. I think that a motor winds up a spring which then knocks a weight downward into the tip of the thing, hammering it into the ground. There's another weight (or something) fired upwards to conserve momentum, and this runs into some kind of spring buffer & so gets rid of its momentum more slowly & doesn't hammer it back up again. this (PDF) is what to look at, I think.
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