We know next to nothing about Uranus. Telescopic observations can only tell us so much, and the only other data we have comes from a flyby mission (Voyager 2) back in the 80’s. To learn more about the 7th planet from the Sun, we need to put a spacecraft in orbit.
Setting Course for Uranus
First of all, you can’t just point your rocket at Uranus and go. You have to aim for where Uranus will be, not where it currently is.
Secondly, there are no straight lines in space. Your course will be a curved trajectory, heavily influenced by the Sun’s gravity and the gravities of any planets you happen to pass near. If you time things right, this can work to your advantage and help you conserve fuel.
Thirdly, once you reach Uranus, you’ll have to slow down enough to be captured by Uranus’s gravity. None of these issues are unique to Uranus, but this third point… this is where Uranus makes things extra challenging.
Slamming on the Brakes
The farther you want to travel into the Outer Solar System, the faster you need to go. Otherwise, the Sun’s gravity will start pulling you back. By the time you get into the general vicinity of Uranus, you’re approaching the kind of velocity needed to leave the Solar System entirely. Then at a critical moment, you have to decelerate rapidly in order to enter orbit.
It’s sort of like flooring it down the highway and then, just as you’re about to zoom right past your exit, slamming on the brakes. I won’t go into the role the rocket equation plays in a maneuver like that. Let’s just say your spacecraft will need a tremendous, stupendous amount of fuel to pull this off.
This is one of the reasons why Voyager 2 was a flyby mission. Even if NASA wanted to enter Uranian orbit, passing up the opportunity to flyby Neptune later, the spacecraft simply couldn’t do it.
A better option for a Uranus orbiter might be to accelerate at a slower pace, taking a much longer, more spirally course away from the Sun, like the MESSENGER mission in reverse. The only problem is that the journey would take many decades to complete, so most of the researchers involved would likely die of old age before the spacecraft reached its destination.
Could We Still Do It?
According to a JPL paper entitled “The Case for a Uranus Orbiter,” we could place a spacecraft in Uranian orbit within a reasonable time span and without breaking NASA’s budget. Such a mission would truly test the limits of current technology, but we could do it.
In some distant Sci-Fi future, full of anti-gravity and warp drive technology, a quick trip to Uranus or Neptune would sound a lot more feasible. But my guess is that even then, hotshot space pilots might find that rapid deceleration to be a bit of a challenge.
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Today’s post is part of Uranus month for the 2015 Mission to the Solar System. Click here for more about this series.