In the twenty-first century what can we realistically hope for in terms of space exploration. Could we reach the Oort Cloud, will there be a Mars Base or even a Titan Base, could we explore the oceans of Europa, getting even more ambitious would it be possible for us to send a probe to Alpha Centauri. Considering what they thought in 1900, how impressed would they be with our progress in 2000?

Well, we are talking about a whole century here. In one hundred years, we went from steam trains to Moon landing, from telegraph to high-speed internet. And now we have an even faster rate of change ramping up, so predictions will be even harder to get right.

There almost certainly will be a permanent Moon base and probably a Mars base, certaily more than one Mars visit. We might send a probe to the Kuiper belt, I'm not so sure about the Oort cloud. Considering there are already (very sketchy) plans for probes to Europa, I'm sure we'll have done something there. Titan might be visited, but probably not a permanent base. Interstellar probe, probably not.

Asteroid mining may have begun at least on a preliminary level. By century's end, the first child will probably have been born in space, and may be old enough to have a child or two. A few orbital space habitats will have been built, and at least one will have made a go of being materially independant of Earth (and knowing human nature, will possibly declare itself politically independant too).

On the downside, the first actual space-to-space combat will probably have taken place.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
Illuminati's Razor-The most complicatedly evil answer is usually the most correct answer. - Fazor
"Every book is a children's book if the kid can read." - Mitch Hedberg
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

We might send a probe to the Kuiper belt,

Well that much I think is likely seeing as we have one hurtling towards there already, to explore two of the biggest known Kuiper Belt Objects in 2015...

There are a lot of unknowns to be resolved before any kind of non-open-ended answer can be given.

If you are asking about manned missions, I'd expect human presence on the Moon, Mars, and numerous asteroids. I'd expect robotic presence in a big way just about everywhere else in the Solar System, including several interstellar probes (not going to other stars, just getting out toward the Oort cloud, not to see cold comets, but to measure stuff from far away).

What happens depends on the advancement of nanotechnology (including bu not limited to carbon nanotubes), electronics, and other technologies.

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That's the one I meant.

No, really.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
Illuminati's Razor-The most complicatedly evil answer is usually the most correct answer. - Fazor
"Every book is a children's book if the kid can read." - Mitch Hedberg
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

I'd say it's possible for us to send at least a flyby probe to Alpha Centauri, but that the amount of scientific return for that investment is perhaps too small to be worth it. I have some ideas for methods to accomplish this with mostly existing technology, but there's no getting around a very large amount of mass that must be launched into space (a large and heavy X-ray laser).

A much lower investment of launch mass in the form of large "eyeglass" or "loopglass" space telescopes could provide much the same scientific return, without even waiting for probes to trek across interstellar space for many years.

The only limitation is our imagination.
Edited: (And the laws of physics.)

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"If you think the LHC will create black holes, you might as well believe Hobbits are at the bottom of your garden."- Dr. Mike Inglis
Rovers forever! - ToSeek
"Carl Sagan sent a message to ET,
Neil Armstrong walked in the Sea of Tranquility
Steve Squyers built Spirit and Opportunity
Dan Haylen upchucked in zero gravity." -Brent Simon, The Space Camp Song

And the laws of physics.

EDIT: Unfortunately, we rarely seem to approach our full potential. We just seem to sort of mediocre along...

__________________
"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
Illuminati's Razor-The most complicatedly evil answer is usually the most correct answer. - Fazor
"Every book is a children's book if the kid can read." - Mitch Hedberg
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

And our budget, and our available resources, and (as noted above) the laws of physics.

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Forming opinions as we speak

By 2099? I'm hoping to celebrate my 124th birthday, truth be told.

In terms of spaceflight:

I see civilian colonies in LEO and on the Moon, with some level of preparation for full scale colonization of Ceres and Mars underway.

I expect to see the first pure spacecraft, built in orbit with no intention of ever landing on a planet, designed for regular transit duty between the Earth and Moon.

I expect to see the first skirmish level battles fought on the Lunar surface between habitats from competing corporations.

I expect to see the first violent crime in orbit.

I predict rovers will crawl across the Mercurian and Venusian surface, with airborne probes on Mars, Venus and, Titan.

I predict a significant level of militarization of orbital space by the end of the century, particularly if unmanned spaceflight capability expands significantly into other nations.

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I'm not completely heartless, the doctor who removed it told me he'd never be able to get it all.

I've always taken a middle-of-the-road approach on space exploration by the end of this century.

One one hand, I think a visitor from today spirited forward to 2100 would be underwhelmed. Basic electronics aside, I don't think the overall technology, materials, and fuels will be much different. I don't think we'll have a space elevator, or independent off-world colonies, and I think space industry outside of power generation and material for in situ use will be only modest. I don't think we'll be much closer to even an unmanned interstellar mission than we are now.

On the other, more optimistic hand, I think the top news of the century will the democratization of space travel. I won't be surprised to see space tourism--hotels and all, even as far as the Moon--become big business in as little as a generation. I think the existence of *several* permanent Moon bases is a near-certainty, and I think the chance of at least one on Mars is better than even. Manned missions to the asteroid belt, and even maybe the outer moons Jupiter aren't out of the question.

For landlubbers, I think tools like GPS and Google Earth are just the beginning; private and public satellite technology integrated more fully into the Internet may make it possible for Joe Blow to be even more informed about what's happening in every odd corner of the globe compared to today--if he cares to look, of course.

By 2100, everything we think we know about the Solar System now will seem almost quaint, due to various unmanned and manned missions gathering ever more data and filling in more blanks. We'll probably know enough about exoplanets to put together Sagan's Encylopedia Galactica, for real, especially if we up up a possible next generation of space telescopes beyond Darwin and GAIA.

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--The State

I essentially agree with antoniseb. To elaborate, the "other technologies" include matters IMO even more important than better thrusters - namely things related to our "inner space" that will help humanity go beyond this planet in the first place.

BIOLOGICAL-PHYSIOLOGICAL SCIENCES (these will ultimately be interconnected. For clarity's sake, one at a time)

DNA engineering: allow us to cure many, if not most cancers. Slow down the aging process, perhaps redesign our maturation process so that we don't begin sexually mature until our brain's fully developed and even our mating preferences (ok, the last two were WAG's - given understandable human fear at redesigning ourselves. But I'm only going by what I think is theoretically possible, not actual use of those techniques)

Neurology: all stuff about the brain applies here. I also expect that we will have gone a long way to identifying the roots of, and thereby achieving some significant control over the worst aspects of mental disorders (psychopathy, excessive narcissism, abuse, other anti-social types of personalities, perhaps even -- important when you realize how important social cohesion and cooperation). There'll still be heartaches and sadness, of course; but we will have more insight into how and why we think the way we do.

Nanotechnology: combine all this with micrometer, if not nanometer, scale programable machines and we will essentially be able to design a human being better equipped to handle space environment (if necessary to implement). Again, expect tremendously heated controversy over "foolishly changing human nature", becoming "spiritual slaves of technology" - on a similar scale not dissimilar to our heated debates about abortion and euthanasia.

Regardless, I think there a few Moon bases, perhaps even a Mars base or two (this millneium's Antarctica, so to speak, only without ecological concerns). We may even have a regular presence in the asteroid belt, given it's mining potential. Venus is a question mark, given its hostile environment it'll originally get LOTS of scary publicity/press.

LEO - Several small orbitals. Research stations, certainly. If not in the 21st century, then certainly in the next, there'll probably be a LEO prison for the most heinous offenders (certainly some private space company will come up with this one). Also, half a chance some private space company will launch a habitat to be populated with idealists, misfits, "hippies" or that era's equivalent, or other kind of eccentric group - to get away from "polluted surface culture", etc.

All in all, it's difficult to know what 2040 will be like - let alone 2099

I think you are generally correct there Filrabat. It will be the combination of other technologies that are not directly tied to space exploration that will have the bigest impact on our future. As you have suggested these will change the very nature of what it means to BE Human along with our understanding of what makes Humans function the way that they do. These will have profound implications upon how individual humans grow and age (or do not age) as well as how we interface with external data sources.

New materials and tools will enable us to do things with ourselves and with robots both large and nanoscale which will seem amazing by today's standards. Each of these technologies will be of great benefit for both the robotic exploration of our solar system as well as enabling biological humans to cope better "off-world".

However unless all of our current understanding of physics has been moving up a "blind alley" then we will still be stuck with the limitations of physical laws as we understand them. This will mean sending any vehicle beyond the inner solar system is going involved flight times measured in years not weeks. Attempting to move any more quickly is going to involve collosal demands of reaction mass that we will regard it as simply not worth the effort. Likewise sending anything beyond our solar system is going to be a very slow process. That said if we ever (though highly unlikely in this century) attempt to send humans beyond the Orbit of Pluto then improved cellular regeneration and extended human lifespan will be essential precursors.

As others have said by the end of this century permanent or near permanent presences on both the Moon and Mars are likely. We will also have probably surveyed and sampled all the planets and moons within the solar system with a high level of precision - though I would hesitate to estimate how much that is done remotely or by humans visiting those places. Beyond that I would expect that we will have a number huge space based telescope arrays operating right across the electromagnetic spectrum which will all us to not only image but gather a considerable amount of information from planets orbiting nearby stars down to including Mars sized worlds. This will at least allow us to fill in a few more gaps in the drake equation. By then it will be possible to produce a reasonable estimate as to how common earth sized rocky worlds are within the Milky Way, not only that but how commonly they occur at the optimum distance from their sun for liquid water to exist. We should also be able to detect the chemical signatures of any ecosystems (if there are any), even if we have no way of determining what sort of complexity of life there might be there. This will at least allow us to put together a galaxy wide probability model for how frequently life occurs - the one question we will probably not be able to answer will be is how often does life go on to become intelligent or civilised. Though if we find a fair number of planets with the signatures of life but no signs of industry or electronic signals then we may have to assume the evolutionary leap from exo-Rat to exo-Homoerrectus is much more improbable event than some people today might expect.

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Note 1. All requests for planetary demolition must now be submitted in quadruplicate on form UX-565/B4 and be counter-signed by the assistant administrative officer for interstellar traffic calming - department QG-7. Subject to approval by the chief planning officer and the infrastructure development coordination sub-committee.

Good question. Revolutionary developments often come faster than we expect. Remember the shock when "Dolly" the first cloned sheep was announced?
I imagine many scientifically educated people had a similar shock back in the '40's when the first atomic bomb was announced. And recently there was much discussion during the 50th anniversary of Sputnik of the impact that it had at the time on the world's consciousness.
There are two developments that I think are around the corner that I think will have a revolutionary impact. The first I think will be purely beneficial, the second will have great positive effects, but unfortunately possibly great negative effects as well. The first is applications of "negative refractive index" materials. I discuss this here:

Newsgroups: sci.astro, sci.physics, alt.sci.planetary, sci.med, sci.bio.misc
From: "Robert Clark" <rgregorycl...@yahoo.com>
Date: 1 Mar 2007 13:17:30 -0800
Local: Thurs, Mar 1 2007 4:17 pm
Subject: New 'superlens' will revolutionize astronomy, medicine, biology.
http://groups.google.com/group/sci.a...3154893ba5f80/

In regards to astronomy, I believe it will make possible tremendous increases in resolution that will no longer be limited by diameter size of the aperture (something previously thought impossible.)

The second development is worrisome. I believe harnessing of antimatter for energy and propulsion is coming near term. This will make conquest of the entire solar system routine. And it will also likely make possible at least unmanned sublight scout missions to the nearest star systems.
I mention a few possible ways antimatter could be stored here:

Newsgroups: sci.astro, sci.physics, sci.physics.relativity, sci.physics.fusion, sci.energy
From: Robert Clark <rgregorycl...@yahoo.com>
Date: Sat, 27 Oct 2007 14:36:36 -0700
Local: Sat, Oct 27 2007 4:36 pm
Subject: Re: Startling amounts of stored energy in fully ionized plasmas.
http://groups.google.com/group/sci.a...ab3668e29e736f

However, the tremendous energy release possible with antimatter of course means it would be studied for use as a weapon:

Air Force pursuing antimatter weapons
Program was touted publicly, then came official gag order.
Keay Davidson, Chronicle Science Writer
Monday, October 4, 2004
"...the Air Force has been investigating the possibility of making use of a powerful positron-generating accelerator under development at Washington State University in Pullman, Wash. One goal: to see if positrons generated by the accelerator can be stored for long periods inside a new type of "antimatter trap" proposed by scientists, including Washington State physicist Kelvin Lynn, head of the school's Center for Materials Research.
"A new generation of military explosives is worth developing, and antimatter might fill the bill, Lynn told The Chronicle: "If we spend another $10 billion (using ordinary chemical techniques), we're going to get better high explosives, but the gains are incremental because we're getting near the theoretical limits of chemical energy."
"Besides, Lynn is enthusiastic about antimatter because he believes it could propel futuristic space rockets.
"I think," he said, "we need to get off this planet, because I'm afraid we're going to destroy it."
http://www.sfgate.com/cgi-bin/articl...NGM393GPK1.DTL

Lynn is a leading researcher on the storage of antimatter. That he would say this is not reassuring in the least.


Bob Clark

The most we could hope for this century is a "technology singularity"-- the development of a conscious AI that thinks so much better than us that it solves all our problems for us. But we can't expect that, or replicating nanoassemblers, or mass production of carbon nanotubes, or build-a-bod human genetic engineering, or mind downloads, or anti-aging treatments, any of the other thousand and one whiz-bangs that are possible but of unknown probability.

__________________
"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
Illuminati's Razor-The most complicatedly evil answer is usually the most correct answer. - Fazor
"Every book is a children's book if the kid can read." - Mitch Hedberg
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

All this speculation depends on the fact that Western Civilization will not have undergone some kind of catastrophic meltdown.

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Keeper of the Jabberwock

True, though the OP was about hope.

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Forming opinions as we speak