The European Space Agency is making final checks ahead of a historic planned landing on a comet on Wednesday.
The Rosetta Space Craft is currently in orbit around comet 67P/Churyumov-Gerasimenko, following a ten year, 6.4-billion kilometre journey around the Sun, Jupiter and Earth.
If all goes well its Philae scout robot will detach from the main craft on Wednesday and begin a seven-hour descent to a spot recently named Agilkia on the edge of the comet.
The landing place is roughly 900 metres by 600 metres, and is relatively smooth compared to the rocky landscapes seen elsewhere on the comet's surface.
The 100-kilogram probe will approach at 3.5 km/hour and fire two harpoons into the surface, before dragging itself towards the comet. Once on the surface it will bore ice screens into the rock. The gravity on the comet is so slight the fridge-sized probe will weight just one gram on its surface.
Rosetta spacecraft in excellent shape," ESA tweeted on Tuesday. "Target locked!"
Once in place the probe will conduct experiments into the makeup of the comet, delivering data which could teach us much about the early life of the solar system, and perhaps even what role comets may have played in seeding life on Earth.
Here is a rough timeline of how it will unfold:
- Midnight - second "go/no go" call to confirm the separation of Rosetta and Philae
- 1.35 am - third "go/no go"
- 8.35 am - Philae separates from Rosetta to start its descent
- 9.03 am - ESA receives confirmation that the separation has occurred
- 1053 am - Philae sends its first signal directly to Earth
- 3.34 pm - Philae lands on 67P
- 4.02 pm - Earth finds out if all the above took place
The first images from the surface will in theory arrive before 5pm and from there the probe will begin its long mission riding on the comet, sending back as much data as possible for about a week.