Hacker News Reader

Comment by Sharlin | Hacker News Reader

I watched ESA's livestream this morning and they explained that Rosetta is actually just co-orbiting the Sun with 67P as of now. They're making it slowly drift to a few different directions and measuring the acceleration caused by the comet's gravity, so they can build an accurate model of the mass and density distribution of such an irregularly shaped object.

View on HN

The hardest part is not so much modeling the comet's gravity, but modeling the aerodynamic effects since at this distance from the Sun outgassing is already taking place at a substantial rate.

It's a big blow to the flight dynamics team that the copyright arrangement for the pictures from some of the onboard scientific cameras makes it impossible for the FD team to use them. Sponsors of the instruments keep denying the permission to guarantee that no competing science and publications can be made before they publish.

So much for putting advancing scientific knowledge first, as opposed to making sure you're the first to publish something.

A very bad side effect of scientists only caring about published results, not acquiring the raw data needed for those published results.

All the incentives in the current scientific system are pushing scientist that way. It is sad, but I think it is a bit unfair to say that the "scientist only care about published results". That is a little like saying a musician only care about money because they copyright their songs and publish on iTunes. I think both scientists and musicians care a lot about music and science, despite how the current system works.

With the masses of the comet and the spacecraft being relatively close, it's hard to tell whether Rosetta is co-orbiting the sun or orbiting the comet itself.

> With the masses of the comet and the spacecraft being relatively close

No, they're not close at all. The comet is three by five kilometers across, and the mass is around 3.14 * 10^12 kg. The orbiter at launch weighs in at 2900 kg and the lander is 100 kg.

http://en.wikipedia.org/wiki/Rosetta_(spacecraft) http://en.wikipedia.org/wiki/67P/Churyumov%E2%80%93Gerasimen...

I think jeroen94704 is saying "With the masses of the comet, and the spacecraft being relatively close"

[comma added]

I disagree. At the very least it would need to be "mass" not "masses". The closest statement should be more like "With the mass of the comet, and the spacecraft being relatively distant."

It's orbiting the sun, however its orbit is such that it will take it around the comet in a roughly triangular shape - but this isn't the same thing as orbiting.

Reply on news.ycombinator.com