The European Space Agency (ESA) reports that following uncertainty of Go/NoGo decision-making, its cometary lander has successfully separated from the Rosetta spacecraft in orbit around the comet 67P/Churyumov-Gerasimenko and is now descending to the comet's surface.

The Philae lander separated from the mother ship Rosetta around 3:30 a.m. ET to begin its 7-hour descent and if it succeeds it will be the first time a spacecraft has landed on a comet.

Philae has spent 10 years fixed to the side of Rosetta during the journey across the solar system and it cannot be steered. Once it was released, it was on its own.

According to ESA lander system engineer Laurence O'Rourke, orbiter Rosetta has to be in the right position to allow the spacecraft to "free fall" on the correct trajectory to the chosen landing site.

The probe will help scientists and researchers learn a lot more about the composition of comets and how they react when they get close to the Sun.

Philae weighs in at 220 pounds and is equipped with an array of experiments to test and photograph the surface of Comet 67P and determining what happens when the roasting effect of the Sun drives off dust and gas.

Hours before separation, Philae's on-board batteries were prepared and a fly wheel is started to give the probe stability on its journey to the comet surface. Without the gyroscopic effect of the fly wheel there's a danger that the lander could turn end over end, O'Rourke said.

The mission controllers now face the long wait for Philae to reach the surface. The comet is very far that a confirmation signal relayed from Rosetta, which remains in orbit around the comet, will take at least half an hour to reach Earth.

At the same time, the comet's gravity is extremely weak that engineers have come up with clever solutions to keep Philae in place. At touchdown two harpoons fire out from the legs and screws on each of the three feet help attach it to the comet.

According to ESA, originally, a thruster on top of the craft was supposed to help push it into the surface, but that system isn't working.

The landing probe has been built by a European consortium, led by the German Aerospace Research Institute (DLR), and has 9 experiments.

O'Rourke said that if everything goes well the first picture should be of the landing site taken by Philae during the final moments of descent, followed by a panoramic image from 7 cameras on the top edge of the lander.

Sensors on the lander will measure the thermal and density properties of the surface, gas analyzers will assist in detecting and identifying any complex organic chemicals that may be present.

Other tests will measure the interaction and magnetic field between the comet and solar wind -- high-energy particles given off by the Sun.