Things have run pretty smoothly for NASA's Mars Insight lander so far, safely touching down on the Red Planet, setting a power record, relaying weather reports and deploying its deep-digging drill on the surface. But mission control has now brought drilling operations ground to a halt, with the probe seemingly snagged on some hardened material beneath the surface.

Our understanding of Mars has improved greatly over the past decade thanks to the work of rovers like Spirit, Opportunity and more lately, Curiosity. But there is always more to learn, and by digging into its surface further than any scientific instrument before it, the InSight lander promises to reveal fascinating new facts about our dusty neighbor.

Key to this is one of the Insight lander's instrument packs called the Heat Flow and Physical Properties Package (HP3). Spearheading the effort, quite literally, is a spiky 40-cm-long (15-inch) probe called "the mole." This is designed to hammer itself into the surface to a depth of 16 ft (5 m) and measure thermal conductivity in the dirt, while a tether tailing behind it takes the subsurface temperature of the surrounding soil.

It is hoped that by measuring the interior temperatures of the planet and better understanding how heat flows through the subsurface, scientists can improve our knowledge of how rocky planets like Mars form.

After deploying HP3 onto the surface midway through February, scientists prepared themselves for the hammering phase. This kicked off on February 28 but hit a roadblock soon after, with the probe only making it around three quarters of the way out of its housing structure before stopping altogether. Hammering was resumed a couple of days later, but to no avail, with data indicating the mole is currently at a 15-degree tilt.

Though the team was hopeful of encountering few rocks beneath the surface, they built the mole to either push smaller ones aside of snake its way between them, a skill it demonstrated successfully in testing prior to launch. But the scientists suspect that it is indeed some rock or gravel that has brought the mole to a halt.

With hammering now paused, investigations will be carried out in search of solutions. Meanwhile, the lander has confirmed that it is measuring thermal conductivity as it should be, and will conduct further tests this week to measure heat emanating from the upper surface.

"The mole is healthy and performed a round of hammering on the weekend," HP3 Principal Investigator Tilman Spohn writes in a blog post. "It has, thus far, continued to work against some resistance without clear evidence for progress. The team has therefore decided to pause the hammering for about two weeks to allow the situation to be analyzed more closely and jointly come up with strategies for overcoming the obstacle."

Source: NASA

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