Nasa today launched a rocket headed to Mars with the Insight probe on board, in a mission to measure quakes on the red planet.
The US space agency worked through the Californian fog at the Vandenberg Air Force Base to get the Atlas V rocket, which is carrying Nasa's Insight probe, into the air at 4.05am local time (12.05pm British Summer Time).
According to Nasa, the probe will burrow three to five metres into the crust of Mars when it lands in November – 15 times deeper than any other Martian mission.
By measuring seismic tremors, or "Marsquakes", the probe will help scientists determine the rock structures under the planet's surface.
This data will then be used to compare with Earth's to help explain how the planets were formed 4.5bn years ago.
Insight will also measure more of the planet's "vital signs", Nasa said, including its heat flows and "precision tracking".
This is not Nasa's first time sending a craft to Mars. It has undertaken a number of missions including the two Viking landers in the 70s, both of which also had seismometers on board.
However the instruments failed to pick up any seismic movements because they were positioned on the bodies of the probes, and wind interference got in the way. Insight, on the other hand, will plant its seismometers in the ground.
The Viking missions did, however, return pictures of Mars and conduct experiments in the soil which led scientists to believe the planet is self-sterilising, and therefore cannot support life.
The latest seismometer experiment is France-led. The country's government-led space agency Cnes and the Institute of Earth Physics of Paris has supplied sensors which will detect low-frequency vibrations, while the UK has contributed three microseismometers which are receptive to higher frequencies.
Meanwhile Germany has contributed the heat measurement equipment.