Re: Interstellar exploration - do we have the technology today?

wsnell01@xxxxxxxxxxx wrote:
How many probes has it taken to explore our own solar
system, and how many planets/moons have yet to be explored in detail?

Exactly. If objects in the Solar System can only be explored in
detail by sending sending probes, or even landers/rovers, why would
one expect large space telescopes to be adequate for studying extra-
solar planets? Telescopes are easier to build than spacecraft, but
ultimately limited.

A telescope in space is not nearly as limited as an interstellar spacecraft. Provided a similar level of spending and technology development to what people envision for an unrealistic spacecraft, the size of telescope I'm talking about (with an aperture measure in km) would be far more efficient.

Eventually we need to send spacecraft to a planet
in order to begin to understand it. Obviously energy/propulsion
breakthroughs are needed for interstellar travel; what we can't say
for sure is whether these will ever emerge or not. Energy creates
wealth, so IF future generations have the energy available, they will
probably send the spacecraft. The other details are trivial by
comparison.

By comparison, yes. That does not make them trivial. And no, I do not agree that energy alone creates wealth, but that is a discussion for another forum.

What I'm saying is that once you consider interstellar exploration, very
large telescopes become a much better choice. This is primarily due to
cost, time, reliability, and the ability to explore more than just one
system.


By the time you could actually consider sending an interstellar probe,
you will probably have already built large space telescopes anyway.
It's not an either/or situation.

I disagree. No offense, but you are greatly underestimating the telescope that I am proposing as well as the challenges facing an interstellar probe. Not only that, but you aren't looking at the limitations of such a probe realistically. This last part -- the failure to carefully consider what a probe could reasonably be expected to accomplish once it arrives is typical when I hear people talk about interstellar probes. But if you look at this part in detail then you are forced to reconsider the whole notion.

The only reason I can think of to send a probe is if we have a very
compelling reason to send it to one specific target, such as a planet
with a very strong indication of life. But even in that case we would
need the super huge space telescope to find it in the first place.


Sort of like studying Mars with a telescope during the late 19th
century, speculating on the existence of life there, then sending
landers in the late 20th century to try to find out. The liquid-fuel
rockets needed for the trip didn't exist in the 19th century, and at
the time a trip to Mars might have seemed forever impractical or even
impossible.

No. That's just my point. People tend to apply the paradigm that they are familiar with from recent history. But that paradigm does not always apply to the future due to changes in circumstances. There was a time when people imagined exploring the moon in great wooden sailing ships that somehow could fly. Of course there would be a captain and crew. That's how it had always been. Great sailing ships may have worked for the oceans, but it turns out that unmanned probes are the most efficient way to explore the solar system. We are faced with a similar change in paradigm when you consider interstellar exploration.

There are three basic options: (1) go yourself and don't ever look back, (2) send an unmanned probe, and (3) build a very large aperture telescope. Of those three the probe is by far the least efficient.

You can't be seriously intending to land your probe on a planet to explore it, are you? Or even enter a low mapping orbit? In the real world all you are likely to get is a fast flyby. Most of what would be learned would be as the probe approached and then receded from still very large distances. Solar systems are enormous! In that case your best bet would be to consider sending an HST-sized telescope to the other system to take "close up" pictures from interplanetary distances. But why do that when you could just build a really big telescope locally?

The utility of a probe is entirely based on getting very close to your target. But just getting to another solar system is not close enough. Think about it. Turn the problem around. A probe arriving in our solar system would be lucky to end up in a 10 AU highly elliptical orbit with an orbital period of 30 years. That's 30 years to go once around this new system. You would have to either build a single probe that could find every planet, accurately determine their orbits, place itself in low orbit, employ appropriate remote sensing (each planet in our solar system requires a unique set of instruments) and then move on to another planet. How long would that take? Yet this is the only way such a probe would be superior to a very large telescope.

Greg

--
Greg Crinklaw
Astronomical Software Developer
Cloudcroft, New Mexico, USA (33N, 106W, 2700m)

SkyTools: http://www.skyhound.com/cs.html
Observing: http://www.skyhound.com/sh/skyhound.html
Comets: http://comets.skyhound.com

To reply take out your eye
.

Relevant Pages

  • Re: Maybe I was right after all
    ... > It struck me the other day that we might be ruining the solar system. ... > planet we are using to sling the probe. ... Maybe we should have a moratorium on using gravity ...
    (sci.space.policy)
  • Re: Interstellar exploration - do we have the technology today?
    ... size of telescope I'm talking about ... Mars-sized planet at 6 LY at the same level of detail as the 2.4-meter ... limitations of such a probe realistically. ... But just getting to another solar system is not close enough. ...
    (sci.astro.amateur)
  • Re: Interstellar exploration - do we have the technology today?
    ... A 10 km aperture for extra-solar work ... the more technology you throw at a probe, imaginary or not, I can match it by imagining something similar for a space telescope. ... if you found a planet that you really wanted to explore very badly only then would a probe make any sense. ...
    (sci.astro.amateur)
  • Re: Interstellar exploration - do we have the technology today?
    ... size of telescope I'm talking about ... Mars-sized planet at 6 LY at the same level of detail as the 2.4-meter ... limitations of such a probe realistically. ...  Or even enter a low mapping orbit? ...
    (sci.astro.amateur)
  • Re: Interstellar exploration - do we have the technology today?
    ... A telescope in space is not nearly as limited as an interstellar ... Mars-sized planet at 6 LY at the same level of detail as the 2.4-meter ... wealth, so IF future generations have the energy available, they will ... limitations of such a probe realistically. ...
    (sci.astro.amateur)