Looking forward to the results. Great international collaboration too.
Unfazed by the outpouring of grief over NASA's admission that its teenaged Opportunity rover had likely trundled its last, the agency's lander, InSight, managed to position its second instrument on the surface of the Red Planet. Ambitious scientists plan to send the device burrowing up to five metres, quite a bit further than …
And a welcome distraction from the various sh*tstorms taking place down here.
I don't know if its just a part of getting older but overall I'm not optimistic about the future of the human race. At least we might leave a few melancholy memorials to our brief existence scattered across the solar system.
Hi guys, I can answer this (I'm an ex-InSight HP3 (i.e. the mole) team member). The Seismometer goes first because, they can actually use the shocks we create with the mole to make measurements of the local geology. The shocks we create, whilst not being that large, create waves which can be picked up by Seis and the reflections of those shocks as they travel through the local area can also be picked up.
Please dont ask me for the exact science involved, I'm a mechanical design engineer, not a geologist! Still they're pretty confident that they can get some good readings based on our short sharp shocks...
I can answer part of that. I am not a geologist, I am a citizen scientists and I've been running my own seismometers for the last 13 years (and I don't have any plans on stopping) and I am heavy into geology.
The shocks allow geologists at NASA to measure if there is any rock and sand layers where InSight is. This also gives geologist general idea on how the crust is at this location.
I'd like to know how they're doing it, as I understand the process there's no rotary drilling or other abrasive action. I assume they already know what depth bedrock is expected under the martian regolith so are not on a hiding to nothing before they start.
In my back garden, I can hit a post with a sledgehammer for an hour and if I've hit a hard, chunky stone just under the surface the damn thing won't budge - they've got to go 5m with virtually no impact power!
The Mole operates basically like a jack hammer. Internally, you have a rotating cam that loads a heavy weight against a spring. At a certain point the spring "slips", releasing the heavy weight with the pent up force of the spring. This sharp shock drives the entire Mole deeper very quickly. The Mole of course bounces back a little bit from this, but at a slower speed where the effect of friction can kick in to grab the Mole and stop it bouncing back to its previous height. Thats the simple version of how it works. :)
As for, do we actually know if it will work - straight up answer - Nope. The mole is strong, it will go through most things so long as it doesnt hit dead on, it will also slide around objects if theres a slope to allow it. It left very nice little furrows in concrete blocks we used for testing just those very scenarios. Still if we hit something dead on, it could be dead in the water, or it could smash its way through - its impossible to know what lies beneath the surface, as Rich Speed writes we havent been deeper than 22cm before. So its all pretty unknown and unknowable.
The Mole itself can be pretty quick, it depends on the soil - i remember one test where we went 5m in about 45mins. When soil conditions are perfect, its fast, other times it can take 12 hours to do the same trip. We just dont know what the soil is like, not exactly. We've designed for a wide variety and tested as many as we could, but you still never know if it works. The talk of a couple of weeks is because every 0,5-1m the Mole will stop for a few days to allow the temperature sensors to do their thing.
A final comment - anything over 3m depth is a successful mission. Science can be done with anything over about 1m if i remember correctly, but 3m means full success. We are actually not allowed to progress beyond 5m. Thats a hard limit put in for planetary protection purposes - to explain that, beyond 5m is so far out of the realm of the known that if we wanted to go further than that, (and technically there is nothing to say the mole couldnt go further with a longer tether), we would have had to go one cleanliness class higher, and that would have upped the costs of the project massively. It just wasnt feasible, so discretion is better part of valour and all that, we'll find out whats past 5m next time... ;)
It seems the landing site was selected using data from the MRO which has ground penetrating radar so you could expect NASA to have a good indication of soil granularity and depth. As you say, baring hitting a rock its not a complete shot in the dark.
Highly informative. cheers
While the MRO data provides a good overview and helped to select a site, the resolution doesnt really tell us anything about what the soil is like. From Wikipedia:
"...[MRO's SHARARD Radar Instrument] allows it to resolve layers as thin as 7 m (23 ft) to a maximum depth of 1 km (0.6 mi). It has a horizontal resolution of 0.3 to 3 km (0.2 to 1.9 mi)."
A resolution of 300m is not great for determining sand grain sizes... ;) :P
Yes I had seen that Wiki entry but then sumised that NASA had probably also factored in data from their other, and possibly the European orbiting radar assets to get the best possible overview of the landing site soil layer.
I just didn't bother typing it ... Cheers again.
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