Beagle 2 has successfully separated from its "mothership" for the final leg of the journey to Mars.
An image from Mars Express' camera showed Beagle 2 drifting away
Mike McKay, flight operations director at the European Space Operations Centre (Esoc) at Darmstadt, Germany, confirmed the separation just after 1110 GMT.
The tiny probe will now glide the last three million kilometres to the Red Planet alone; silent, powerless and in hibernation mode.
The lander is expected to touch down on Mars on Christmas Day, to search for signs of life, past or present.
Commenting on the historic success at a press conference, Beagle 2's creator Colin Pillinger said:
"We were out to play a two-leg match and both of them were away. In fact, a long way away from Earth.
0710 GMT - Green light for separation granted
0831 GMT - Separation command given
1031 GMT - Contact was re-established
1110 GMT - Confirmation of launch
1400 GMT - Image of launch released
"We've travelled 250 million miles and we've got a one-nil result in the first leg.
"We're playing the second leg on Christmas morning and I'm a real, real hard taskmaster because I'm going to demand that everybody comes along and witnesses that event on Christmas morning."
Afterwards, he was asked whether he was concerned about whether apparent dust storms on Mars would affect the landing.
"My information is very much that it's not going to be a big concern," Professor Pillinger told BBC News Online.
"Tick a box, move on, tick another box, we're not happy until we get to the surface," he added.
Science minister Lord Sainsbury told BBC News Online:
"This is the riskiest and most difficult part of it, which is the actual landing on the surface. They've done everything conceivable to make sure that this really does come off and work.
"But it's high risk stuff and I just want to wish them the best on this next step."
A pyrotechnic device fired to slowly release a loaded spring, which gently pushed Beagle 2 away from the mother spacecraft.
A picture taken by Mars Express' onboard camera showed Beagle drifting away from the orbiter.
Beagle 2 will spin away on a path that should eventually pop it into the top of the Martian atmosphere.
The lander has no propulsion system of its own and relies on accurate positioning to reach the desired landing site, a vast plain just north of the Martian equator.
But the ejection procedure was the first of a series of high-risk manoeuvres required to land Beagle 2 on the Martian surface.
Steve Burnage, head of technology at the UK defence firm Insys which built Beagle 2's separation mechanism told BBC News Online:
"We were pretty confident we'd done all the testing. But you never know, [Mars Express] was a long way away. But it worked out, it was good news."
After flying solo for almost six days, the lander should reach the edge of the Martian atmosphere in the early hours of Christmas Day.
It will plunge towards the crater of Isidis Planitia slowed by a heat-resistant shield and parachutes, and cushioned by airbags.
Meanwhile, Mars Express will fire its rockets to blast itself into orbit around the Red Planet.
It will then begin its life's work - searching for water, ice and key chemicals buried under the Martian surface.