NASA looks at a DEEP space probe

[ToSeek]

Some of us will count ourselves lucky to see the science results from this one:

Voyage to the Stars: NASA Study Mulls Options

To send a spacecraft where none has gone before is a dream assignment for any space scientist and engineer.

The idea of dispatching a dedicated robotic probe on an interstellar trek has been seriously advocated for nearly 30 years. A recently finished appraisal of how to build such a craft shows that it is within reach -- but nonetheless remains a challenging task.

A NASA-sponsored study team has blueprinted an Innovative Interstellar Explorer (IIE).

Goal of the IIE would be to plunge outward some 200 Astronomical Units. An astronomical unit (AU) is the mean distance between the center of the Earth and the center of the Sun - approximately 93 million miles (150 million kilometers).
...
If launched in 2014, the probe would arrive at the 200 AU distance in about 2044.

[badprof]

Just a thought on this. Since the Oort cloud is part of our solar system and is believed to be in the order of 50,000 AU from the Sun, how could they call 200 AU "Interstellar"?

[jfribrg]

Just a thought on this. Since the Oort cloud is part of our solar system and is believed to be in the order of 50,000 AU from the Sun, how could they call 200 AU "Interstellar"?

My guess is that if it is beyond the heliopause, then the conditions are the same as they would be at 150000 AU, so it's called interstellar.

[John Kierein]

I prefer saying that interstellar is where other star systems' gravity exceeds the sun's. It would be directional in this case. In the direction of the nearest star, it would be a shorter distance than away from it.

[NEOWatcher]

I prefer saying that interstellar is where other star systems' gravity exceeds the sun's. It would be directional in this case. In the direction of the nearest star, it would be a shorter distance than away from it.

I understand what your saying because the clear influence is then not our sun. I prefer the beyond the Ort cloud, since that seems to be the last item thats in our influence. Kind of like saying in or out of the city, even though its not well defined, I wouldn't want to go half-way to another city to be considered in the country. If I smell it, then I'm in the country.

[publiusr]

Smacks of the old TAU mission.

[ToSeek]

Just a thought on this. Since the Oort cloud is part of our solar system and is believed to be in the order of 50,000 AU from the Sun, how could they call 200 AU "Interstellar"?

Because it sounds really, really sexy, and it's more compact than "Innovative Explorer That Goes Really Really Far".

[Saluki]

I would define "inter-stellar" as something that actually crosses over into the influence of another star. If it stays within the influence of our star, then it is "intra-stellar".

Edit: If I am calculating correctly, 200 AU is aproximately 1.15 light days. That is piddling compared to inter-stellar distances.