Messenger spacecraft crashes into Mercury

NASA's Messenger spacecraft smashed into the surface of the planet Mercury this afternoon, ending four years of orbiting and studyingthe closest planet to the sun.

The dramaticimpact took place at3:26 p.m. ET today, following a series of goodbye tweets.

The spacecraft had runout of propellant andthe force of the sun's gravity was enough tocause it to fall and crash into the surface of Mercury,NASA said.

• Mercury's quirks revealed by NASA spacecraft
• Mercury's North Pole has ice, NASA confirms

Messenger, which has been orbiting Mercury since March 2011, was expected to smack into theplanet at 3.91 kilometres per second (14,000 kilometres an hour) andleave a crater 16 metres wide on the planet's surface.

The impact tookplace on the side of Mercury facing away from Earth, giving the spacecraft some privacy during its last moments.

However, Slooh, an organization that broadcasts astronomical events online, offeredan opportunity for people to take part in the event via awebcast featuring mission scientists such asNoam Izenberg, who wasanswering questions from the public.

Messenger, launched in August 2004, is the first spacecraft ever to orbit Mercury. In the past four years, it has snapped more than 270,000 images of the planet and made measurements that have revealed many surprises including:

• Ice on the planet's north pole, despiteits closeness to the sun.
• Lopsidedness in the planet's magnetic field, which is stronger in the northern hemisphere.