Inner secrets of Mars

NASA’S Mars lander Insight successfully landed on Mars early in the morning of November 27 our time, after a journey of six and a half months.

It has been settling in quite nicely, and all indications are that it is going to be a highly successful and rewarding mission.

Not long after landing, its solar panels opened correctly, and will provide up to 700 watts of power to the spacecraft so that it can carry out its operations in the next two years.

Previous landers have concentrated on surface studies but Insight’s aim is to learn more about the interior of Mars.

Because of this, it was necessary to select a landing site that was expected to be flat, and relatively free of large rocks: a safe site, rather than a geologically interesting one, was the priority.

Also, in order for its solar panels to provide enough electrical energy, it needed to land quite close to the Martian equator.

The chosen site was Elysium Planitia, just north of the equator. The name Elysium comes from ancient Greek mythology as being a peaceful place for good people in the afterlife, which is also known as the Elysian Fields. Planitia is the Latin name for a plain, or flat surface.

I am impressed with the first images from the lander! They show that the surface on Elysium Planitia is much as expected. The craft is level, on a flat plain on which rocks can be seen generally scattered across the surface, but which will not prove to be an impediment to Insight’s operations.

It was also important to ensure that Insight’s heat flow probe would be likely to be able to burrow deeply — up to about five metres — into the Martian soil. This probe will measure the rate at which heat is leaving the planet, offering important clues as to the makeup of its interior. To ensure that the probe would likely be able to drill to the required depth, some teamwork was involved with another Martian spacecraft: the Mars Odyssey orbiter.

Mars Odyssey has been in orbit around Mars since 2001, and one of its instruments, called THEMIS, was used to determine that Insight’s probe should be successful.

THEMIS measures the rate of heating and cooling on Mars, and because of the high rate of temperature change in Elysium Planitia, it was deduced that Insight would land on relatively soft ground rather than in an area with a lot of solid rock.

Insight also has an extremely sensitive seismometer, called the Seismic Experiment for Interior Structure (SEIS), which will detect even the most minute of ground movements. A parallel here is that scientists use earthquakes to learn more about our planet’s interior, too.

Hopefully the SEIS will work well; before the planned 2016 launch of Insight, the instrument was found to have a fault, and fixing it caused a delay in the launch until 2018.

So far, so good, and there were certainly cheers and hugs when the Insight team learned of the successful landing.

It’s always an anxious time for the mission controllers as a spacecraft enters orbit around, or lands on, a planet or moon. Mars is no exception, with quite a number of failures having occurred.

However, Insight has become NASA’s eighth successful Mars lander, which is impressive. The first were Viking 1 and Viking 2 in 1976, followed in 1997 by Pathfinder, and in later years by the Spirit and Opportunity rovers, Phoenix, and Curiosity. Curiosity is still operating in Gale Crater, and is only 600km from Insight’s location.