Maximum Velocity Currently Attainable? The Future?

[Diche Bach]

It is my understanding that the fastest space craft to date were the Helios probes:

“The probes are notable for having set a maximum speed record among spacecraft at 252,792 km/h[1] (157,078 mi/h or 43.63 mi/s or 70.22 km/s or 0.000234c).â€Â

I make this out to be 4213.2km / minute or 70.22km /second.

http://en.wikipedia.org/wiki/Helios_probes

However, a substantial portion of this velocity is a result of the probes inescapable orbits around the sun, i.e., their ‘falling toward the sun.’ As such, I would think it is arguable that the fastest ‘controlled velocity’ (in the sense of an orbital trajectory from which the craft still could carry enough delta-V to change to a substantially different orbit) is held by either the New Horizons spacecraft (which achieved the fast launch velocity at 16.5km/second; or perhaps the Voyager I spacecraft, which is leaving the solar system at 17.145 km/s (all according to the respective Wiki pages).

Obviously, the idea that Voyager I could perform anything like a substantive trajectory maneuver at this point is probably pretty questionable.

With all the recent media attention paid to exo-planets, and wild speculations like "it is probable that the Milky Way has a hundred million Earth-like exoplanets . . ." etc., I feel that a reasoned consideration of our capacity to attain very high speeds is quite needed; if nothing else to temper potentially unrealistic enthusiasm about prospects of interstellar colonization at any time in the near future.

Certainly the discovery of exoplanets excites me as much as anyone! But it doesn't mean that we are actually _any_ closer to going interstellar, a somber point that I do think deserves about as much attention as all the cool finds in recent decades.

I have been trying to dredge up some of my past posts on this from another forum (1BC Civilization forums) but cannot get a search that hones in and sifting through all 10,000 of my posts on that site is too tedious!

However, I did some maths to calculate the travel times to various star systems which have now famous exoplanets, as well as the nearest stars (Proxima Centuari, etc.). The number I came up with were rathering sobering.

It seems like the fastest travel time I came up with for say Proxima Centauri was about 40,000 years!

So with this thread I’m asking you guys to discuss the topic of:

1. Using current technology, and every trick in the book (e.g., multiple years of flyby maneuvers around objects in our solar system??) how fast could we conceivably ‘go?’

2. How long will it be before humanity really has any reasonable prospect of reasonably ‘quick’ interstellar travel?

Or any other related question that you choose to talk about!

I was gonna post this to the xkcd.com thing but I just barely have glanced at that. If one of you guys feel like it would make a good ‘what if’ question (e.g., What if a contemporary space probe was sent on multiple repeated flybys around objects in our solar system, how fast could it conceivably get up to?) for that guys blog I’d love to hear what he has to say.

Edited August 14, 2013 by Diche Bach

[Fuzzy Dunlop]

Using current technology we can't go that fast at all, voyager is acctually travelling slower than earth orbits the sun (hence it acctually gets closer to use for a few months of the year). NASA's Solar Probe+ will exceed 200 km/s, but that's using the Helios style sundiving strategy (only much much closer)

[Diche Bach]

Using current technology we can't go that fast at all, voyager is acctually travelling slower than earth orbits the sun (hence it acctually gets closer to use for a few months of the year). NASA's Solar Probe+ will exceed 200 km/s, but that's using the Helios style sundiving strategy (only much much closer)

Yep.

So here is a related question that may expand on the discussion: art their any credible plans to develop technology to go faster? What are those technologies likely to look like? How long till they could be brought to fruition?

I've noticed that, when it comes to these discussions, at least as they manifest on things like Wikipedia, there seems to be a big jump between reality and the "what we might do" conceptions that are essentially nothing more than intereting theories. For example, Wormholes, antimatter drives and the like seem to get brought into discussions and it seems to me that those are basically make believe.

Is that really the best we got? The prospect of reasonable journeys to other stars depends on make believe?

[Seret]

Is that really the best we got? The prospect of reasonable journeys to other stars depends on make believe?

Yes. Interstellar distances are tyrannically large, and care not for what we find "reasonable".

We currently have no technology for bridging interstellar distances, and there's no significant research being done into exotic propulsion suitable for interstellar flight. Sorry.

Exoplanets are extremely interesting bodies, but will remain tantalisingly beyond our reach for a long, long time. We're going to have to be satisfied with what we can learn of them observationally. FWIW there's plenty for us left to do in the solar system. We've only just begun to explore it, we have so much more to do. There are hundreds (or thousands) of planets, minor planets, moons, etc that we can reach in only a few years.

Edited August 14, 2013 by Seret

[Pugspaceprogram]

Theoretically we can travel at 10,000 km/s. This was project Orion. Scientists thought that it would be capable of reaching 3% the speed of light by using nuclear explosions. The original concept was to go to mars by A-bomb but by then, the project fell flat. Scott Manley did a neat video on Orion, and I recommend that you check it out.

[Diche Bach]

Wow. So we really are still primitive ape guys using fire and plumbing.

Will check out Scott's Orion video!

One more specific question that I'm curious to hear if any of you guys can answer: is there some sort of practical limit to how much velocity can be added to a vehicle using nothing more than fly-by maneuvers and course corrections?

So for example, if you had simply a very large rocket (lots of liquid fuel) could you just keep doing fly-by after fly-by and (as long as you still had more fuel to execute the maneuvers) just keep adding more and more velocity?

Edited August 14, 2013 by Diche Bach

[Mr Shifty]

So for example, if you had simply a very large rocket (lots of liquid fuel) could you just keep doing fly-by after fly-by and (as long as you still had more fuel to execute the maneuvers) just keep adding more and more velocity?

The planet's ability to affect your velocity depends on how fast you're going (relative to the planet). If you're going too fast, you'll just fly by the planet with very little change in your orbital direction, no matter how close you get, so there is a theoretical limit to gravity assists.

[Diche Bach]

The planet's ability to affect your velocity depends on how fast you're going (relative to the planet). If you're going too fast, you'll just fly by the planet with very little change in your orbital direction, no matter how close you get, so there is a theoretical limit to gravity assists.

More or less what I expected. So conceivably, an ideally designed and scheduled craft could use a modicum of its delta-V to get up to some theoretical maximum from gravity assists, then kick in the antimatter or nuclear explosion boosters and head off into the deep black beyond!

ADDIT: Ahhh, well that's not really particularly helpful is it. Looks like the highest velocity planet in our solar system is Mercury at about 48km/s . . . I suppose really if you wanted to use the big kahuna it would be a flyby around the SUN! but that is probably a very long term maneuver . . . Wiki tells me sun is only going 220km/s relative to center of the galaxy so . . . that pretty much answers my question! Flybys are NOT a viable solution to interstellar travel although they might offer some minimal assistance to save on fuel.

Found this reading up on the Orion's wiki page: Antimatter space propulsion at Penn State, kinda disheartening to see the citations are the early 90s and the last time the page was updated was more than 10 years ago

Edited August 14, 2013 by Diche Bach

[SargeRho]

With current technology we can go up to 10% the speed of light. It would require a huge solar sail.

[Diche Bach]

Yeah, 10% seems to be about what they think the "bomb driven" ship would offer too.

Hell, 10% ain't too bad! That would be about 40 to 50 years to Proxima Centauri? Hard to imagine how that would work, but yeah doable I guess.

Would suck pretty bad if a multi-generational crew arrived there and found, "Welp! Nothing here! Just a couple useless gas giants a lot of radiation. Guess we just head home?"

[Khrissetti]

an orbit to drop our periapsis as close to the sun as we dare, followed by a burst of Orion explosions, followed by a couple of gravity assists is probably the best way I can think of pulling some serious velocity....

[SargeRho]

Yeah, 10% seems to be about what they think the "bomb driven" ship would offer too.

Hell, 10% ain't too bad! That would be about 40 to 50 years to Proxima Centauri? Hard to imagine how that would work, but yeah doable I guess.

Would suck pretty bad if a multi-generational crew arrived there and found, "Welp! Nothing here! Just a couple useless gas giants a lot of radiation. Guess we just head home?"

Hence why we need to get our hands on Antimatter or Warp propulsion systems.

[Diche Bach]

Can't they produce a fair bit of antimatter now, but they just can't really store it?

[SargeRho]

Yeah, storage is the big problem. But antimatter is already in use, in PET scanners. PET stands for Positron Emission Tomography, It uses a positron emitting radionuclide. The positrons annihilate with electrons, creating gamma ray pairs.

Now, there is a proposed Spaceship that would produce antimatter using lasers and store it. This would allow it to do roundtrips to nearby stars. Called VARIES:

What would be awesome though, is a spaceship that can take up energy like the Destiny in Stargate Universe rather than using solar pannels

[Anton P. Nym]

Can't they produce a fair bit of antimatter now, but they just can't really store it?

"Fair bit" in terms of our use today, yes. "Fair bit" in terms of using it for rocket fuel, no. Current annual global production is measured in nanograms, about a billionth what would be needed to support an antimatter-fuelled space program.

That being said, we're getting better at making and storing the stuff all the time so there's a chance I'll live long enough to see the infrastructure put in place.

-- Steve

[Diche Bach]

"Fair bit" in terms of our use today, yes. "Fair bit" in terms of using it for rocket fuel, no. Current annual global production is measured in nanograms, about a billionth what would be needed to support an antimatter-fuelled space program.

That being said, we're getting better at making and storing the stuff all the time so there's a chance I'll live long enough to see the infrastructure put in place.

-- Steve

Well heck! Nanograms per year is a lot (infinitely?) better than zero per year! Seems like it wasn't even that long ago that they weren't even sure if it really existed or could exist?

When I just consulted the wiki page on antimatter, I was pretty surprised at how blasé it sounded about "Mmm, yeah. We produce some antimatter. Not much. It has some uses in medicine and industry. If we could store a lot of it, we could maybe make a cool starship . . . "

My memory is certainly not infallible. But I recall not long ago reading something more along the lines of "Antimatter is theoretical state of matter that is the opposite . . ." and that they had not yet managed to measure it being ephemerally produced in nature nor produce it articially, eh?

[Seret]

With current technology we can go up to 10% the speed of light. It would require a huge solar sail.

Neither solar sails nor Orion are current technology, since neither have gotten beyond studies. There's a massive difference between an idea on paper and one that can actually be used. Often there are fundamental technical roadblocks that prevent implementation. Take the idea of space elevators for example. Perfectly valid idea on paper, but there are numerous materials and technical problems that mean we can't actually build one.

There are some good ideas for exotic propulsion systems, but none we could actually build yet.

[SargeRho]

Solar Sailers have been used in space at least once. We just haven't built one the size needed for interstellar travel yet.

[Seret]

Solar Sailers have been used in space at least once. We just haven't built one the size needed for interstellar travel yet.

Ah, looks like you're right. A small-scale demonstrator was used in space in 2010. Still a hell of a long way to go between that and a practical form of propulsion though. The IKAROS experiment managed to grab itself 100ms^-1, which is somewhat short of 0.1c.

[SargeRho]

The first solar sail was actually tested in 1993 on the Mir, although propulsion was not demonstrated. The MESSENGER probe used its solar pannels as solar sails for course corrections, and Hayabusa used its pannels to aid in attitude control.

[Anton P. Nym]

Neither solar sails nor Orion are current technology, since neither have gotten beyond studies.

Actually ORION went through a series of tests with a miniature model using conventional explosives. I'd also argue that many of the principles of ORION were tested when we thought lighting off fission devices in the open air was a good idea... in particular, the ablative oil coating for the pusher plate was tested several times, and one underground test failure blew a hatch off so hard that if compressive heating hadn't vapourised it it'd have reached escape velocity...

-- Steve

[Bunsen]

Well heck! Nanograms per year is a lot (infinitely?) better than zero per year! Seems like it wasn't even that long ago that they weren't even sure if it really existed or could exist?

When I just consulted the wiki page on antimatter, I was pretty surprised at how blasé it sounded about "Mmm, yeah. We produce some antimatter. Not much. It has some uses in medicine and industry. If we could store a lot of it, we could maybe make a cool starship . . . "

My memory is certainly not infallible. But I recall not long ago reading something more along the lines of "Antimatter is theoretical state of matter that is the opposite . . ." and that they had not yet managed to measure it being ephemerally produced in nature nor produce it articially, eh?

The first theoretical prediction and experimental observations of antimatter (positrons, specifically) happened around 1930ish. It took a couple more years for them to put two and two together and realize that those weird-looking solutions to Dirac's equation and those spirals going the wrong way in the cloud chamber were the same thing. I've met plenty of people who think antimatter is hypothetical just because it's such a standard feature of science fiction.

Fun bit of trivia: the average banana, thanks to potassium-40 decay, produces about one positron per minute.

[Seret]

Actually ORION went through a series of tests with a miniature model using conventional explosives. I'd also argue that many of the principles of ORION were tested when we thought lighting off fission devices in the open air was a good idea... in particular, the ablative oil coating for the pusher plate was tested several times, and one underground test failure blew a hatch off so hard that if compressive heating hadn't vapourised it it'd have reached escape velocity...

-- Steve

But this is my point. None of this stuff has got beyond the "fiddling about" stage. The OP was asking if there was any serious work being done on exotic propulsion for interstellar flight. It would be nice to be able to say yes, but...

Fun bit of trivia: the average banana, thanks to potassium-40 decay, produces about one positron per minute.

Which leads us on to my favourite ever unit: the BED!

[Diche Bach]

The first theoretical prediction and experimental observations of antimatter (positrons, specifically) happened around 1930ish. It took a couple more years for them to put two and two together and realize that those weird-looking solutions to Dirac's equation and those spirals going the wrong way in the cloud chamber were the same thing. I've met plenty of people who think antimatter is hypothetical just because it's such a standard feature of science fiction.

Fun bit of trivia: the average banana, thanks to potassium-40 decay, produces about one positron per minute.

Wow, 1930s!? Amazing. After my last post, I spent a few more hours browsing wiki pages and did notice a mention of one lab that produced anti-helium as early as the 1970s . . . but I would never have guessed that the models much less the empirical findings were actually 40 or 50 years older than that!

To me as a social scientist, it is really nice that you guys indulge these questions and misunderstandings so graciously and good-naturedly. I have to say, compared to the pettiness, ideologically dogma and the way many social scientists treat themselves far too seriously, I find the obvious undercurrent of humor among physical scientists and engineers to be refreshing.

Also in 1936, Anderson and his first graduate student, Seth Neddermeyer, discovered the muon (or 'mu-meson', as it was known for many years), a subatomic particle 207 times more massive than the electron, but with the same negative electric charge and spin 1/2 as the electron, again in cosmic rays. Anderson and Neddermeyer at first believed that they had seen the pion, a particle which Hideki Yukawa had postulated in his theory of the strong interaction. When it became clear that what Anderson had seen was not the pion, the physicist I. I. Rabi, puzzled as to how the unexpected discovery could fit into any logical scheme of particle physics, quizzically asked "Who ordered that?" (sometimes the story goes that he was dining with colleagues at a Chinese restaurant at the time). The muon was the first of a long list of subatomic particles whose discovery initially baffled theoreticians who could not make the confusing "zoo" fit into some tidy conceptual scheme. Willis Lamb, in his 1955 Nobel Prize Lecture, joked that he had heard it said that "the finder of a new elementary particle used to be rewarded by a Nobel Prize, but such a discovery now ought to be punished by a 10,000 dollar fine." [3]

Re: the BED . . . so it just might be the massive banana caches could be the key to efficient production of interstellar spacecraft fuel!?

[NGTOne]

in particular, the ablative oil coating for the pusher plate was tested several times, and one underground test failure blew a hatch off so hard that if compressive heating hadn't vapourised it it'd have reached escape velocity...

Don't forget the part where the hatch cover weighed about 2 tons

Re: the BED . . . so it just might be the massive banana caches could be the key to efficient production of interstellar spacecraft fuel!?

So... my plan is, take a thousand monkeys and lock them in a room... I can only hypothesize that the result would be a) an exotic, banana-powered spaceship, and Jebediah Kerman. Planet of the Apes indeed (or is that Galaxy of the Apes)?