Professor Colin Pillinger, the British planetary scientist behind the 'Beagle 2' mission to Mars, has died at the age of 70.
Pillinger suffered a brain haemorrhage at his home in Cambridge and fell into a coma, a statement from his family said.
He died at Addenbrooke's Hospital after failing to regain consciousness.
Pillinger's family said the loss was "devastating and unbelievable".
He became a professor in interplanetary science at the Open University in 1991, where he led the Department of Physical Sciences until 2005, and earned a host of other qualifications and awards during his prestigious career - which included work with NASA.
But he was best known for his work as lead scientist on the unfortunately doomed Beagle 2 mission to find life on Mars.
The space craft was last seen heading for Mars on December 19 2003, after separating from its European Space Agency mothership Mars Express.
The craft was supposed to land on the planet on Christmas Day, but instead vanished in the atmosphere.
It was the first time that an individual researcher had sent a craft into space to search for life, and was widely admired and closely followed by the public. Pillinger was brutally disappointed by the mission's failure, but was awarded the CBE for his work in the same year.
Prof Pillinger was diagnosed with multiple sclerosis in 2005.
He said at the time that the illness would not stop his efforts to get Beagle technology back on Mars.
He lobbied Nasa to include technology similar to that on Beagle 2 in its most recent Mars lander, the Curiosity rover, and maintained that sending human explorers was largely pointless unless we could first establish the existence of life on the surface.
On Twitter figures from the worlds of science, entertainment and media all paid tribute to Pillinger's dedication and ability to inspire the public with his against-the-odds campaign to discover life on another planet:
So farewell then Colin Pillinger. Your Beagle press briefings were the nearest many of us science writers got to thrill of Apollo 11 #beep— David Firn (@davidfirn) May 8, 2014