Not a furry mole, of course; the term is the nickname for the instrument formally known as the Heat Flow and Physical Properties Package on board NASA's InSight lander mission.

"After several assists from my robotic arm, the mole appears to be underground," the official Twitter account for the mission wrote yesterday (June 3).

Related: NASA's InSight Mars lander 'hears' Martian wind, a cosmic first.

It's a completely new type of instrument for Mars but, although the team tested it extensively in chambers of dirt on Earth, such analogs can never precisely match circumstances on the Red Planet.

And so, just about as soon as the mole set out on its Martian dig, it struggled, getting stuck or backing out.

That's a delicate proposition since the InSight team needed to be careful to not damage the tether connecting the mole to the lander.

After several assists from my robotic arm, the mole appears to be underground.

But according to a new blog post from Tilman Spohn, the German space agency scientist leading the mole team, this technique finally yielded some progress.

The mole is now nearly entirely buried in the Martian soil, he wrote, with the scoop at the end of the lander arm near the surface.

(Because the mission's instruments were supposed to be fully deployed by now and project personnel have other work to complete, the lander can only work on the mole problem once a week, slowing progress further, Spohn wrote.)!

"Winter is approaching on Mars' northern hemisphere and dust storm season will begin soon," Spohn wrote.