NASA's InSight completes halfway to Mars

NASA's InSight spacecraft, en route to land on Mars this November, has passed the halfway mark, covering 277 million kilometres since its launch 107 days ago.

In another 98 days, it will travel another 208 million kilometres and touch down in Mars' Elysium Planitia region, where it will be the first mission to study the Red Planet's deep interior.

InSight stands for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport.

The InSight team is using the time before the spacecraft's arrival at Mars to not only plan and practice for that critical day, but also to activate and check spacecraft subsystems vital to cruise, landing and surface operations, including the highly sensitive science instruments.

InSight's seismometer, which will be used to detect quakes on Mars, received a clean bill of health on July 19.

The SEIS instrument (Seismic Experiment for Interior Structure) is a six-sensor seismometer combining two types of sensors to measure ground motions over a wide range of frequencies. It will give scientists a window into Mars' internal activity.

"We did our final performance checks on July 19, which were successful," said Bruce Banerdt, principal investigator of InSight from NASA's Jet Propulsion Laboratory in the US.

The team also checked an instrument that will measure the amount of heat escaping from Mars. After being placed on the surface, InSight's Heat Flow and Physical Properties Package (HP3) instrument will use a self-hammering mechanical mole burrowing to a depth of 3 to 5 metres.

Measurements by sensors on the mole and on a science tether from the mole to the surface will yield the first precise determination of the amount of heat escaping from the planet's interior.

The checkout consisted of powering on the main electronics for the instrument, performing checks of its instrument sensor elements, exercising some of the instrument's internal heaters, and reading out the stored settings in the electronics module.

The third of InSight's three main investigations -- Rotation and Interior Structure Experiment (RISE) -- uses the spacecraft's radio connection with Earth to assess perturbations of Mars' rotation axis. These measurements can provide information about the planet's core.

"We have been using the spacecraft's radio since launch day, and our conversations with InSight have been very cordial, so we are good to go with RISE as well," said Banerdt.

The lander's cameras checked out fine as well, taking a spacecraft selfie of the inside of the spacecraft's backshell.

"If you are an engineer on InSight, that first glimpse of the heat shield blanket, harness tie-downs and cover bolts is avery reassuring sight as it tells us our Instrument Context Camera is operating perfectly," said InSight Project Manager Tom Hoffman from JPL.

"The next picture we plan to take with this camera will be of the surface of Mars," he said.

If all goes as planned, thecamera will take the first image of Elysium Planitia minutes after InSight touches down on Mars.