The first spacecraft to study the deep interior of Mars will attempt today a perilous descent to the dusty surface.
Just 40% of missions to the red planet have safely made it through the thin atmosphere.
NASA hopes combination of a heatshield, parachute and retrorockets will slow InSight from 13,000mph to 5mph in just six minutes.
The stakes are so high for the £630m mission that NASA controllers will be passing round peanuts for luck, a superstition that began with an earlier successful space probe.
Tom Hoffman, InSight project manager at NASA, said: "I will control myself as far as possible until we get the first notification of a successful landing, but then I will unleash my inner four-year-old."
InSight will land on the Elysium Planitia, a featureless plain just north of the location of the Curiosity rover.
Once it has unfurled its solar panels it will ram a temperature probe five metres into the surface to measure the heat flowing from the planet's core.
It will also activate a seismometer, an instrument that will "listen" for tremors.
These could be from meteorites striking the surface, but scientists also hope to detect Marsquakes.
The speed of the shockwaves as they bounce around and through the planet will allow scientists to work out whether it has a solid or liquid core.
The instrument was designed by a team at Imperial College London.
It's so sensitive that when the engineers tested it at a lab in Oxford they were able to detect the vibrations from church bells being rung on a Sunday morning.
If the instrument establishes that Mars has the remains of a liquid core it will suggest the planet once had a magnetic field that could have shielded early life – before dramatically and mysteriously weakening.
Professor Tom Pike, who led the Imperial team, told Sky News: "On Earth our magnetic field is important for protecting us from radiation and also protecting our atmosphere from being swept away by solar winds.
"Mars, although it may have started off in a similar place, is now certainly very different.
"It's drier, it's lost almost all of its atmosphere and there's very little water.
"If life did ever establish itself early on, Mars has been a difficult place for it to hang on."
More from Mars
NASA missions have established that billions of years ago the planet was warmer and wetter, more conducive conditions for life.
In 2020 it will land another rover in an ancient lake bed to directly look for evidence of microbes, dead or alive.