First, an earlier post indicated that there hadn't been ANY hyperbolic orbits for comets, but, in fact they are rare but not unheard of. Generally, they are not VERY hyperbolic.
Originally posted by GOURDHEAD
@Mar 9 2004, 02:47 PM
The cloud would be more galactic than solar. If so, what contribution, assuming densities below current detection thresholds of current electromagnetic detection techniques, would such a population contribute to the dark matter enigma? How can such a wild guess be falsified?
Theory: Current theories suggest that the Oort cloud was formed as objects in the Kuiper belt, and further in were thrown out during the planet formation period. Some objects escaped altogether, and some are within the grasp of Solar gravity. These would all be in highly elliptical orbits with perihelions in the planetary solar system, mostly around Neptune's orbit.
Detection: all the comets in the Oort cloud combined might have the mass of a lump of ice about 1000 miles in diamter [like a large Plutino]. Total number is a wild guess. It could be 100 times more than this, which is still a tiny fraction of the Solar system mass. We may never be able to detect these object via their gravity. The objects spend the vast majority of their time in the outer parts of their orbits. They are very cold and dark, even in the near infrared. If you knew exactly where one was, you could illuminate it with a high powered laser. It might take a year for the reflection to come back.
Galactic Comets: There should be escaped comets from the formation of every planetary system, and these would mostly orbit the galactic center with orbits similar to the parent star system. Once in a while we should, and do, see comets with some excess velocity. So far we haven't seen anything obviously from a grossly different orbit than ours, but they must exist.
Dark Matter: The total unseen baryonic matter is about three or four times the mass of the visible stars. The free comets from the birth of our solar system are probably much less than the mass of the Earth. These things can't come close to making up the difference. The total non-baryonic missing mass according to the current LCDM theory is about six time more than all the baryonic matter [seen and unseen].
Mission: There is a sort-of planned mission called the Interstellar Probe. This thing is sometimes chopped out of the budget, and sometimes put back in. The mission isn't to go to another star, but simply to get to the interstellar medium, and inner part of the Oort cloud within ten years of being launched. There is no concrete plan for how it will get their, they seem to be accepting ideas at this stage, and a launch won't happen for at least ten years, and maybe more. The mission has no plan to specifically look for an Oort Cloud member, as we have no clue where they are.
Forming opinions as we speak