Relativistic Navigation Needed For Solar Sails

KentuckyFC writes "Last year, physicists calculated that a solar sail about a kilometer across with a mass of 300 kg (including 150 kg of payload) would have a peak acceleration of roughly 0.6g if released about 0.1AU from the Sun, where the radiation pressure is highest. That kind of acceleration could take it to the heliopause — the boundary between the Solar System and interstellar space — in only 2.5 years; a distance of 200 AU. In 30 years, it could travel 2500AU, far enough to explore the Oort Cloud. But the team has discovered a problem. Ordinary Newtonian physics just doesn't cut it for the kind of navigational calculations needed for this journey. Because the sail has to be released so close to the Sun, it becomes subject to the effects of general relativity. And although the errors these introduce are small, they become magnified over the course of a long journey, sending the sail roughly 1 million kilometers off course by the time it reaches the Oort Cloud. What these guys are saying is that if ever such a sail is launched (and the earliest estimate is 2040), the navigators will have to be proficient in a new discipline of relativistic navigation."

Re:You knew what this mission was when you signed

[SBrach]

They are relatively better at the calculations??

Shouldn't this be irrelavent...

[Churla]

Wouldn't this be completely besides the point as long as we keep enough spice in their tanks? They can always just think their way back on course.

Just how big is the Oort Cloud?

[Eevee]

From Wikipedia, "The Oort cloud is a hypothetical spherical cloud of comets which may lie roughly 50,000 AU, or nearly a light-year, from the Sun." So...um...how do you miss it? You go straight out in any direction. When you see a lot of icy chunks floating around, you're there.

Re:Computers?

[drseuk]

Tough choice for NASA: Use MS Excel 2040 and end up a million km off course or use Linux and have the sail get where it's supposed to be for 1st January 1972. Simples!

Need to think relatively

[Lev13than]

Course correcting a small ship is easy - I'm more worried about everything else. In a relativistic navigation model, the ship is going to be in exactly the right place. However, the energy required to course correct the entire universe by one million km will be prohibitive.

Re:One part in 37 million...

[R2.0]

I would think that the Oort cloud itself would be the destination. Theoretically, the distribution of rocks is pretty even, so we should be able to get data no matter where in the cloud the probe goes. If it gets to that random point and finds either nothing, or a whole lot, we need to change the theory, don't we?

Remember, Columbus set out to sail to the Indies, not land in Mumbai harbor. Of course, if we follow that example the probe will crash into Neptune and we'll declare it a new comet, but the general principle is the same.

Re:Just how big is the Oort Cloud?

[fuzzyfuzzyfungus]

Asteroids do not concern me, Minwee. I want that ship, not excuses.

I already use relativistic navigation

[140Mandak262Jamuna]

I don't know what the big fuss is about relativistic navigation. Almost every day my close relative sits on the passenger seat tells me where to go. Some times my other close relative sits in the back seat and tells me where to go. Being used to that kind of relativistic navigation, I wonder why NASA is so puzzled.