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Comment by johnnyApplePRNG | Hacker News Reader

That's a rate of about 4.3 centimeters per hour.

Can anybody elaborate as to why this process takes so long?

As the hole gets deeper, the amount of time to bring up core sections and send the drill back down become significant. That combined with the previously mentioned short field season. Drilling more than a few hundred meters becomes very difficult logistically as well, especially in such a remote setting.

Like fetching the n-th element from a linked list by starting at the first node.

Who knew, drilling is O(N^2)

It's not O(N^2) is it? It can be a continuous line of ice being pushed up. Depending on the weight bearing ability of the lift and digging capacity, you would figure out a fixed distance after which you would place the buckets to carry up the ice.

Its an interesting interview question at the very least. (More complications arise as and how you get deeper into the ice).

You can't have a continuous line of ice coming up, unless you're digging for slush. Each intact X-meter core must be hauled up on its own, and then the drill has to go back down. The deeper you are, the longer it takes to haul up one core and send the drill back down. So, retrieving the cores is clearly O(N^2).

Drilling the core itself is O(N), but as you go deeper the core retrieval dominates. Not to mention everything getting more complex the deeper you go.

Anyone who has hung a heavy picture/frame? :-)

(you need to pull the drill out periodically to let the dust out, and the distance of that pull increases with depth. But it is O(K1 * N^2 + K2 * N) where K1/K2 are pull-out and drilling-in (both seconds per mm), and for short holes most of the time will be drilling not removing dust.

We need a couple more bore holes to do a Tower of Hanoi style question for interviews.

It's not a continuous 24/7/365 process. They have a drilling season each year, I believe about 6-8 weeks, have drilled at 2 different sites and been interrupted by the pandemic.

why was ice drilling interrupted by the pandemic?

Getting supplies such as food and shift changeovers?

International travel was not easy nor reliable during the pandemic, with many borders de facto closed or severely restricted, with quarantines, tests, etc.. needed. The drilling season involves moving an international team from each of their home countries to Greenland, then back again a few weeks later. So practically impossible to make sure the drilling season could happen with the crew required and then get them home again.

Every country I know of had special exemptions in place though, after the first few weeks of panic, for those who could supply credible written explanations.

it's a very high aspect ratio hole (267:1) so they have to peck-drill it and it takes a very long time to lift the drillbit to remove the swarf from the end

I'm going to see if I can work the term "swarf" into conversation tomorrow. (We all need goals.)

I've never drilled a hole with 10m diameter before, but I imagine they've been more careful about taking and studying cores than you were.

Surely you mean 10cm?

My word. I and at least one other poster here were misled by the picture at the top of the article.

But, for whatever it's worth, a trip to Wikipedia tells me that they took 2 years off, due to covid.

It's more realistic to say that covid caused logistics issue two summers in a row. The first summer was presumably 2020 when almost every country locked down. In 2021 things weren't much better and the various polar programs were dealing with both caution and a backlog of issues from the previous year.

The actual downtime may have been significantly less than 24 months but still could have killed progress for 36. There's a pretty small window that you can deploy for these sorts of operations.

I believe the deeper the layer of ice, the thougher it is, so at the surface is relatively easy to drill but at those depths it might be like drilling on steel.

Did you store the tube of ice?

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