There is some sad news from NASA this week, as two major space probes have both been declared dead within the last few days.

Just two days ago, NASA announced that the 9 1/2 year old Kepler space probe, which has detected thousands of new exoplanets over its near decade long mission, had stopped working. Some readers may remember that earlier in the year the control team were having some trouble with the probe, but managed to get it working again. This time it is more serious and more permanent, as the Kepler space probe has exhausted its fuel supplies and therefore can no longer be re-oriented towards different star systems. And since it can no longer be rotated, it also can no longer take any significant data on distant worlds. It had a great run, and certainly no one could call the Kepler mission a failure or feel too bad at this loss, but it is still a little unfortunate that the search for exoplanets will now be stalled until a new, improved space telescope can be launched.

Then while astronomers were still discussing the loss of Kepler, today it was announced that the Dawn mission has also come to an end.

The Dawn probe was launched eleven years ago with the goal of visiting the dwarf planets Vesta and Ceres, which are among the smallest planets in the inner solar system and orbit inside the asteroid belt between Mars and Jupiter. It was the first man-made object to be placed in orbit inside the asteroid belt, and during its mission it first orbited Vesta, before being transferred to the larger Ceres for further scientific study.

As with Kepler, the Dawn probe had been operating for several years past its expected expiry date. However in recent weeks it was becoming clear that the fuel reserves were nearly depleted, and so the Dawn probe will no longer be able to be re-positioned either. It will now stay in orbit around the dwarf planet Ceres, and according to some analysts may remain in orbit for over a decade.

And so there are mixed feelings with both of these historic missions. It is certainly sad to see these missions end, and the data that they collected and sent back to Earth will be analysed by scientists for many years to come. However they both performed well beyond any expectations and have each earned a place in scientific history for their major contributions to our understanding of planets both in our own solar system and in other, distant star systems.

But we can be assured that as these two missions end, new ones will soon begin and will take us even further in our collective knowledge of the planets and the stars...