One spacecraft could visit all of Saturn’s inner large moons

For those who’ve ever performed Kerbal House Program, you understand how tough it may be to get your spacecraft into the orbit you need. It is much more tough in actual life. For this reason it is fairly spectacular to see a proposal to check all of Saturn’s giant interior moons in a single go.

At a broad degree, orbits are fairly easy. Planets and moons are mainly ellipses. As soon as set into movement, spacecraft usually observe an elliptical or parabolic path, so it is only a matter of lining up your spacecraft’s orbit together with your vacation spot and level of origin. You are able to do the calculations by hand if the maths. A number of early science fiction authors akin to Robert Heinlein and Hal Clement did simply that to make sure their space-travel tales have been correct.

However most of these easy calculations solely decide fly-by paths, and so they do not bear in mind energy-saving methods akin to gravitational slingshots. The vitality calls for of getting a spacecraft to the outer solar system are so excessive that even the early missions to Jupiter and past relied on gravitational assists, that are tough to calculate.

And as we have seen from missions akin to Juno and Cassini, it is extraordinarily helpful to place a spacecraft in orbit round a planet so now we have loads of time to collect information. Ideally, for one thing akin to a mission to Saturn, you’d need to attain the ringed planet in an affordable time, then transfer right into a collection of orbits across the planet that makes a number of flybys of attention-grabbing moons, however that is a giant ask for a mission.

One of many challenges has to do with orbital vitality. To achieve Saturn rapidly, you’d have to construct up an excessive amount of pace. To get into orbit you must take a lot of that pace away. That is significantly difficult if you need your spacecraft to orbit deep within the planet’s gravitational nicely. For the Cassini mission, the staff reached a compromise utilizing orbits that dipped near the interior moons of Saturn infrequently. This was tremendous as a result of a primary focus of Cassini was the moon Titan, which is comparatively distant from Saturn.

For a return mission to Saturn, astronomers would like to get a superb view of Enceladus. We all know it has loads of liquid water, and it is a wonderful candidate for all times. Nevertheless it’s deep inside Saturn’s gravitational nicely, with an orbital radius solely one-fifth that of Titan. For the time being, the strongest proposed mission is the Enceladus Orbilander, which might orbit the moon for about 18 months. However this may stop the mission from deeply learning different Saturnian moons.

That is the place this new proposal is available in. Reasonably than merely specializing in Enceladus, why not spend time round all the main moons of Saturn? To attain this, the staff proposes a fancy set of orbits that depends on an electrical propulsion engine. Also called an ion thruster, such an engine might present a tiny quantity of thrust over prolonged instances. The concept is to progressively shift orbits moderately than shifting orbits in a single go. These dynamic orbits are actually tough to calculate, however they’re extraordinarily vitality environment friendly and may be adjusted over time.

Of their proposal, the staff reveals how electrical propulsion might energy a mission to go to not solely Enceladus and Titan, but additionally Dione, Tethys, and Mimas. Relying on priorities, the mission may very well be put in orbit round every of those moons, making a number of shut approaches to every world. Relying on the size of the mission, the electric propulsion may very well be both solar or nuclear powered.

This preliminary proposal is only a proof of idea, nevertheless it reveals that the subsequent mission to Saturn does not have to decide on between Both Enceladus or one other moon. It is doable to take a grand tour of the Saturnian system if solely we may be steely-eyed concerning the orbital paths we select.

The findings are revealed on the arXiv preprint server.