It’s hard to believe that it’s already been a week since Rosetta arrived at comet 67P/Churyumov-Gerasimenko! But while the race is now on to map and analyse the comet in order to find a suitable landing site for Philae in November, we’re also looking much further ahead into the mission. That is, to perihelion, exactly one year from now.
Perihelion is the term used to describe the point in an object’s orbit that it is closest to the Sun. For comet 67P/Churyumov-Gerasimenko, the next perihelion passage falls on 13 August 2015, when it is about halfway between the orbits of Earth and Mars, at a distance of about 186 million kilometres (1.24 AU) from the Sun.
Screen shot from “Where is Rosetta?” interactive tool. Click image to visit tool.
The image shown here is a screen shot from our popular “Where is Rosetta?” tool, and indicates the relative positions of the comet and spacecraft with respect to Jupiter, the inner Solar System planets, and the Sun, today (note the red line shows Rosetta’s ten year journey; in the recently updated version of the tool you can toggle this off). The blue line traces the path of the comet, which is currently between the orbits of Jupiter and Mars. Use the tool to slide through the year and watch how the distances – and speed of the comet (and Rosetta) – change as perihelion approaches.
During this time, the comet will heat up and become more active, throwing out increasing quantities of gas and dust. Rosetta will continue to accompany the comet even after perihelion, as it moves away from the Sun again, monitoring how its activity decreases and providing unique insight into both daily and long-term changes taking place on and around the comet.
At the same time, the ever-changing activity will make for hugely challenging operations as the team try to keep the spacecraft close enough to the comet to do good science, while ensuring that it remains safe. It’s going to be a quite a ride!
Discussion: 5 comments
With thoughts of the later-stages of the mission… has anyone on the team seriously considered what the final fate of Rosetta will be? Maybe a controlled touchdown (near Philae?) would be an option as we saw at Eros with NEAR-Shoemaker? Now that would seem fitting and an option that doesn’t need to be concerned with planetary protection measures. Any thoughts or is it too early to say?
Continuing congratulations to all.
Too early to know just yet!
Lets talk some “if”s now…, rather, let me phrase some assumptions and questions, if I may.
Lets assume everything works as brilliant as it did up until now and the lander will touch down on the comet in November.
* Will the landing module be able to send home its data autonomously, or will it need Rosetta as a relay station, therefor, being dependent on Rosetta’s orbiting position relative to the landing site?
So, for the sake of getting on lets assume Philae will need Rosetta. Then, with approaching Perihelion the comet will be getting more active, perhaps forcing Rosetta to retreat its orbit for safety reasons.
* Is there a max distance between Rosetta/Philae where data transfer is not possible anymore?
* What if – the creator of the universe help us to prevent it – what if Rosetta gets damaged beyond repair at some point during the mission, will Philae be lost as well?
Philae will use Rosetta as a relay to Earth, yes. The lander has an initial battery lifetime of approx 64 hours (may be more if it can successfully recharge using its solar panels) so it is expected that the lifetime of the orbiter will in any case be much longer than the lander; Philae is scheduled to land in November this year before the activity of the comet increases significantly, while Rosetta is expected to stay with the comet at least through 2015. But, as you point out, its distance to the comet may vary depending on the comet’s activity. This is partly why the spacecraft is currently approaching the comet slowly, so that we can learn more about the environment before going even closer, and so hopefully avoiding the situation that any damage will occur!
Just 64 hours lifetime for Philae… wow, I wasn’t aware of that. But, thinking about it now, its just obvious as its quite small and relatively light and so not much room left for any power sources. So, all the more lets hope everything goes smooth and fine.
What will Rosettas orbit be during these crucial 64 hours? Will it stay stationary above Philae to receive data, or will continue to cicle through its orbit around the comet then, so getting data only at certain positions in orbit?
Thanks for the reply! 🙂