GEOFF BENNETT: A two-month-long expedition to Antarctica has brought scientists and researchers to the widest glacier on earth, the Thwaites Glacier.

It's also nicknamed the Doomsday Glacier because of its potential impact to raise sea levels if ice continues to melt.

Our science correspondent, Miles O'Brien, is on that trip.

The primary challenge for many of the researchers, they're trying to drill a small hole on the glacier at the place where ice, land and the sea meet some 3,000 feet below, the so-called grounding line.

The instruments they drop into the seawater could yield unprecedented data.

Miles has been visiting the base camp today and has this look at the challenges of what they're doing, part of our recurring series Tipping Point.

MILES O'BRIEN: So, how do you drill a hot water hole into a glacier 3,000 feet?

Well, the first thing you need is a lot of hot water.

And, fortunately, there's a pretty much never-ending source of snow here.

Behind me, these are called flubbers.

The team here, there are 10 people here, had to shovel over the course of the past week or so 20 tons of snow into those containers.

They are truly practicing oceanography the hard way.

It's hard work.

The weather was terrible, but they got what they needed to do this hot water drill hole.

Let's take a look at what else is going on here.

OK, so shoveling 20 tons of snow is just for starters.

You got to melt it.

So those three boxes over there, those are generators.

They're connected to those three boxes with heaters.

There's two, four, six of them.

That turns the snow into water at 194 degrees Fahrenheit.

It gets sent through this black hose.

This is the key drilling hose on that black spool and it goes down the hole.

There are two other spools there that are very important.

The orange spool, which they're using right now, is how you drop down instruments that don't need to communicate with the surface, things like cameras and so forth.

The silver spool right there, that's coaxial cable.

It can carry data.

So if you have an instrument where you want to keep reading the data as it goes down, you use that.

Hard to believe 3,000 feet below where I stand, we're actually floating on the Amundsen Sea, but this is how you get all the scientific instruments, get the data that scientists are so interested in finding about why this glacier is melting so quickly.

This is the science tent.

This is the stuff that's going down the hole.

And everything here has to be working before they begin drilling, so I don't want to touch anything.

I'm going to sit down here and be very careful not to break anything.

Basically, they will be sending down instruments that measure the salinity, the temperature, the current of the water, the sedimentary picture.

And here's what's kind of cool.

This tower is part of a structure that will be left here with instrumentation all the way down through the glacier to the Amundsen Sea, so that scientists will be able to get real-time data continuously for hopefully a number of years on what's going on here.

What are the temperatures?

What is happening beneath this glacier?

Why is it melting so quickly?

GEOFF BENNETT: And Miles O'Brien joins us now from the Thwaites Glacier.

So, Miles, how's it going there?

I know there's limited time to get this work done.

MILES O'BRIEN: Yes, this is truly deadline pressure stuff, Geoff.

You and I can relate to it in our business, but they are truly under the gun, and they have run into a little bit of a snag.

As you can -- might be able to tell right here, they're working on the end of the drill hose right behind me with a crescent wrench.

About 30 feet beneath the surface as they went down, they encountered crevasse and -- essentially an open cavern which extends down about 20 or 30 feet and then it goes back into solid snow.

So you have got this open space.

And you can imagine drilling a hot water hose down and all of a sudden you're in this cavern.

How are you going to keep the hose from wobbling, and how do you get the instruments to connect with the hole at the bottom of the cavern, so to speak?

So they're kind of running through this.

They have never run into this before because they have always drilled in places that were more benign.

But this glacier is collapsing so rapidly that the crevasses are everywhere.

So they sort of expected to run into them.

But this is taking their drilling technique and technology to a new level, Geoff.

GEOFF BENNETT: And, Miles, remind us what they're measuring for and why.

MILES O'BRIEN: Well, the Thwaites Glacier is melting orders of attitude, several times more faster than its neighbors here in Antarctica.

And scientists are pretty certain that it's being eaten away from beneath by warm currents in the Amundsen Sea.

There's a whole climate change connection to that has changed the wind currents around Antarctica, which has allowed this warm water to really be 3,000 feet beneath where I stand right now well above freezing.

And so the question is, how much more above freezing is it?

How -- what are the currents there?

What is the nature of the melt right now?

And by doing this and getting this data, they can actually come up with good predictions, models and forecasts for what happens here and to other glaciers in this vicinity.

They may not be melting as rapidly, but Thwaites is sort of a keystone which holds them back.

And this glacier alone represents about 2.5 feet of sea level rise all over the world.

The other glaciers added up about 10 feet.

So it's worth paying attention to.

GEOFF BENNETT: So what happens from here?

Where are the next steps?

MILES O'BRIEN: Well, they got to figure out how to get through this crevasse and make sure that all the instruments that go through that open space.

I'm sure they will figure that out.

But the clock is ticking.

They only have so much fuel to keep those heaters going, keep the snow, turning it into hot water.

And the ship has to leave for New Zealand at -- last day of work here is February 7.

So they're under the gun to get this done.

They need about three days of drilling and science operations, so into the weekend.

And, hopefully, they will get through this little obstacle right now and, by the end of the weekend, they will have made a little bit of scientific history.

GEOFF BENNETT: And, Miles, can I ask you what it feels like atop the glacier there?

What's the temperature?

MILES O'BRIEN: It's down low 20s.

But I got to tell you, Geoff, the wind here has a quality which is very distinct coming off the ice.

When you feel the wind, it just cuts right through you.

So I am well bundled up, as you can see.

But we know every moment that we are in Antarctica.

GEOFF BENNETT: Yes, I was going to say, we're dealing with low 20s here on the East Coast, but certainly not glacial winds.

(CROSSTALK) GEOFF BENNETT: So, Miles O'Brien, our best to you and the team there in Antarctica.

Thanks, as always.

MILES O'BRIEN: You're welcome, Geoff.