Nasa's Mars InSight mission heads for '7 minutes of terror'

The InSight lander is being targeted at a flat plain just north of the planet's equator called Elysium Planitia.
It carries a suite of instruments - many of them from Europe - to try to determine the rocky world's internal structure.
Signals from the probe confirming its safe touchdown should be received at 19:53 GMT, give or take a minute.
As with previous surface missions, InSight must survive the "seven minutes of terror" - the time it takes for a probe entering Mars' thin atmosphere at hypersonic speed to slow to walking pace and gently put itself on the ground.
Many have tried; most have failed. "As humanity, as explorers - we're batting at less than 50%," said Nasa's science chief, Thomas Zurbuchen. "Going to Mars is really, really hard."