Project Longshot 1987-88

[Spaceception]

Project Longshot Was US Navel academy/NASA project that ran from 1987-88 and proposed launching a unmanned starship to Alpha Centauri b at ~5% light speed, the trip would've taken 100 years. The probe would've been built at the proposed space station freedom and used closed long lived fission reactor for power with a fusion engine similar to the one Daedalus would've used, the ship weighed 396 metric tons.

So what do think of it? And what do you think would've happened to society and spaceflight if we built/launched it?

[magnemoe]

Its an flyby I assume. Surprisingly light for an starship.
Not much would change in the 100 years before flyby, it would give lots of nice pictures during flyby, lots of data who would raise more questions. 
If it was life at an planet we would know before it left and the pictures would give an push for an manned mission or at least robotic landers.
Even without life on any planets it would be very interesting to see alien planets up close. 

[tater]

Then the Trisolarians come.

[Nibb31]

I don't think we are technically capable of building any complex system that can last 100 years, let alone a nuclear reactor. 

Arriving at Alpha-Centauri would get you some nice data on the binary star. I don't think we have detected any planets there (I wonder how stable a planetary orbit could be around a binary star), but even if there are planets, the chances of arriving close enough to take pictures would be practically nil. There is no way you could reprogram the probe since any new commands would only be received long after it has left the system, so it would need some really sophisticated AI to pick a target and divert its course autonomously.

All in all, it would be a huge effort, but I'm not sure that the impact be that big.

Edited February 18, 2016 by Nibb31

[Spaceception]

Just now, Nibb31 said:

I don't think we are technically capable of building any complex system that can last 100 years, let alone a nuclear reactor. 

Arriving at Alpha-Centauri would get you some nice pictures of the binary star. I don't think we have detected any planets there (I wonder how stable a planetary orbit could be around a binary star), but even if there are planets, the chances of arriving close enough to take pictures would be practically nil. There is no way you could reprogram the probe since any new commands would only be received long after it has left the system, so it would need some really sophisticated AI to pick a target and divert its course autonomously.

We've fond evidence of a earth-sized planet around Star b, and no, not the one that was found in 2011; That one probably doesn't exist, this one was found in 2013 I think.

17 minutes ago, magnemoe said:

Its an flyby I assume. Surprisingly light for an starship.
Not much would change in the 100 years before flyby, it would give lots of nice pictures during flyby, lots of data who would raise more questions. 
If it was life at an planet we would know before it left and the pictures would give an push for an manned mission or at least robotic landers.
Even without life on any planets it would be very interesting to see alien planets up close. 

No, it was designed to slow down.

[magnemoe]

8 minutes ago, Spaceception said:

We've fond evidence of a earth-sized planet around Star b, and no, not the one that was found in 2011; That one probably doesn't exist, this one was found in 2013 I think.

No, it was designed to slow down.

It was designed to slow down, That is way better performance than I excepted.
And yes before launching this we are likely to have something far larger than the web telescope, with an starshade to make it easier to map planets. 
In short we would know as much about the planets around it as we knew about Pluto before the flyby. In short we would know size, mass, atmosphere content, we would also have mapped large continents. 
Without life it would be another planetary expedition, only far more exiting. 
With life it would be an giant event, we would probably know about large areas covered with vegetation and perhaps if its forest like or more like grassland before but nothing else.

So that do we find: Perhaps first contact 
That would change a lot of things. 

[wumpus]

So they worked on for one out of the projected 30 or so it would take... [so just add a Mr. Fusion to run it...]

While they mention the longevity of the Pioneers and Voyagers for "working with old probes", they really don't go into the issues of dealing with half-lives.  They mention that He-3 is a must  (no half-life issues), but dealing with the NTRs (you can use solar power once you get there, but you need to run the engine on NTRs to slow down first) is another story.  Exploding the He-3 is another issue: has anybody ever done such without using a fission bomb (it sounds like the National Ignition Facility has made the most well-funded attempt and didn't come close).  Storing fission bombs for a century is likely iffy tech.  Either the DoE doesn't need most of the fancy new computers it has bought over the last few decades, or this is still unknown/tippy-top-secret tech (also every physicist in Iran and North Korea knows how to build a fission bomb.  Building a fission bomb that can stay on the shelf for a few months was at least beyond the folks at Los Almos for nearly a decade.  DoD/DoE can be expected to keep an even tighter grip on such issues than they might have in MAD days of 1987/1988).

Summary of issues:

Fusion drive at least as far from production as in 1987/1988.

NTRs require long half-life fuels with resulting mass issues.

Bit rot is going to be nasty (expect to be using 1987/1988, [or more likely 1976 RCA 1802 chips, with some nasty anti-bit-rot circuitry]).  Engineers will learn a lot about n-9s design before completion.

Shock/Vibe: most mil-spec units are only expected to survive a single high-g shock event.  This thing will get one per bomb (to maintain any amount of efficiency).  Expect *nothing* to work as expected until *many* tests are done.

 

Edited February 18, 2016 by wumpus
thought of shock/vibe issues. 2nd. No, I didn't work on it myself and can't believe I implied I did. Not intentional.

[fredinno]

2 hours ago, Nibb31 said:

I don't think we are technically capable of building any complex system that can last 100 years, let alone a nuclear reactor. 

Arriving at Alpha-Centauri would get you some nice data on the binary star. I don't think we have detected any planets there (I wonder how stable a planetary orbit could be around a binary star), but even if there are planets, the chances of arriving close enough to take pictures would be practically nil. There is no way you could reprogram the probe since any new commands would only be received long after it has left the system, so it would need some really sophisticated AI to pick a target and divert its course autonomously.

All in all, it would be a huge effort, but I'm not sure that the impact be that big.

Binary star orbits are surprisingly stable, at least closer in.

[tater]

It's unclear if it is truly a trinary system, or if Proxima is a transient---but for the next long while, it's more than a binary system (Proxima is far enough out, and tiny, so it's more of a pedantic issue, like what to label Pluto).

Edited February 18, 2016 by tater

[kerbiloid]

If they launched this 100-years journey in 1988, then in 2088 humans would get scratched and blurry photos of α Centauri — to compare them with nice and sharp 3d-images made by a constellation of extraterrestrial telescopes had been launched in 2070.

Also, such project would cost as a constellation of trans-Neptune Hubbles with 80 AU triangulation base.

[magnemoe]

8 hours ago, kerbiloid said:

If they launched this 100-years journey in 1988, then in 2088 humans would get scratched and blurry photos of α Centauri — to compare them with nice and sharp 3d-images made by a constellation of extraterrestrial telescopes had been launched in 2070.

Also, such project would cost as a constellation of trans-Neptune Hubbles with 80 AU triangulation base.

None would launch it in 1988, it was just an case study to check the requirements.
You are right that telescopes are better use of money, however you would not get good images even with giant stuff, think an telescope of 500 meter in the outer system, yes that is optical telescope larger than any radio ones, it would take as good pictures of extrasolar planets as Hubble does of Pluto, it would also require an starshade, an free flying disc to block out the star the planet orbit around, Using multiple smaller would work but you still need lots of mirror area as you don't get many photons. 

Requirements was surprisingly low for an interstellar mission, something who could be launched this century its not an megaproject. For an flyby probe laser pumped solar sail is probably better unless an flyby version of longshot could would be far smaller. 

[PB666]

On 2/18/2016 at 9:34 AM, Nibb31 said:

I don't think we are technically capable of building any complex system that can last 100 years, let alone a nuclear reactor. 

Arriving at Alpha-Centauri would get you some nice data on the binary star. I don't think we have detected any planets there (I wonder how stable a planetary orbit could be around a binary star), but even if there are planets, the chances of arriving close enough to take pictures would be practically nil. There is no way you could reprogram the probe since any new commands would only be received long after it has left the system, so it would need some really sophisticated AI to pick a target and divert its course autonomously.

All in all, it would be a huge effort, but I'm not sure that the impact be that big.

Voyager is almost 50.

[wumpus]

9 hours ago, kerbiloid said:

If they launched this 100-years journey in 1988, then in 2088 humans would get scratched and blurry photos of α Centauri — to compare them with nice and sharp 3d-images made by a constellation of extraterrestrial telescopes had been launched in 2070.

Also, such project would cost as a constellation of trans-Neptune Hubbles with 80 AU triangulation base.

Have you looked at the difference between the Hubble and New Horizons pictures of Pluto?  The laws of optics needed to focus light hasn't changed much.  Being 2500 times closer will still have an advantage.

A bigger problem was that the idea wasn't a 1988 launch but a 2018 launch.  Unfortunately, the biggest progress on a fusion drive is a longer list of things that don't work (my other complaints listed above would make it expensive, but certainly possible).  Is the Isp of such a drive even measurable?  It looks like we could do a fly-by mission with ion drives now (give it thirty years to accelerate...), but for any reasonable ship that wouldn't remotely be capable of doubling the delta-v requirements to slow down... and thus leaving it quite possible that solar-system bound telescopes *could* get a better view of the various planets/lesser stars.

Is my math wrong or do you really need 9,000,000 m/s delta-v to get to Alpha-cent in under a century (and another 9Mm/s to stop)?

[Nibb31]

1 hour ago, PB666 said:

Voyager is almost 50.

It's also pretty rudimentary compared to an interstellar probe. It barely survives on a dwindling RTG and most of its instruments are dead.

[Spaceception]

6 minutes ago, Nibb31 said:

It's also pretty rudimentary compared to an interstellar probe. It barely survives on a dwindling RTG and most of its instruments are dead.

So? The point is we can build spacecraft that can last for decades, it still has power, right? It can still use some of its instruments, right? If we put work into it, we could double, triple or even quadruple its lifespan using an actual nuclear reactor.

Edited February 19, 2016 by Spaceception

[fredinno]

1 hour ago, Spaceception said:

So? The point is we can build spacecraft that can last for decades, it still has power, right? It can still use some of its instruments, right? If we put work into it, we could double, triple or even quadruple its lifespan using an actual nuclear reactor.

Not really, but it shows that ~50 year probe designs, though expensive, are possible.

[kerbiloid]

16 hours ago, magnemoe said:

None would launch it in 1988, it was just an case study to check the requirements.
You are right that telescopes are better use of money, however you would not get good images even with giant stuff, think an telescope of 500 meter in the outer system, yes that is optical telescope larger than any radio ones, it would take as good pictures of extrasolar planets as Hubble does of Pluto, it would also require an starshade, an free flying disc to block out the star the planet orbit around, Using multiple smaller would work but you still need lots of mirror area as you don't get many photons. 

Requirements was surprisingly low for an interstellar mission, something who could be launched this century its not an megaproject. For an flyby probe laser pumped solar sail is probably better unless an flyby version of longshot could would be far smaller. 

Yes, if you use a single telescope, its images would be poor - as Pluto from Hubble.
But if you are using several Hubbles at once, with a large triangulation base, coordinating them with a computer net and using computer-based statistical methods to filter out noise from the signal, that's another tale.
Afaik this is why the astronomers can study extrasolar planets even now. Sometimes even their surface details (for hot Jupiters, of course).

Requirements were surprisingly low while this design concept has not been started to be implemented by engineers - at least because
"Needless to say, including enough fusion fuel to slow an object traveling at these speeds to brake into orbit around Centauri B would require an engine far more efficient and powerful than anything envisioned for Daedalus.".

Edited February 20, 2016 by kerbiloid

[Camacha]

15 hours ago, fredinno said:

Not really, but it shows that ~50 year probe designs, though expensive, are possible.

The problem is that we have little to no experience engineering for these kinds of lifespans, especially when it comes to complex electronics. The best option we do have is probably making everything redundant to a ridiculous level, relying on statistics to get the mission to become a success.

The probes and craft that managed to survive the longest generally did that by a bit of engineering and a lot of luck. It is a roll of the dice.

[fredinno]

12 hours ago, kerbiloid said:

Yes, if you use a single telescope, its images would be poor - as Pluto from Hubble.
But if you are using several Hubbles at once, with a large triangulation base, coordinating them with a computer net and using computer-based statistical methods to filter out noise from the signal, that's another tale.
Afaik this is why the astronomers can study extrasolar planets even now. Sometimes even their surface details (for hot Jupiters, of course).

Requirements were surprisingly low while this design concept has not been started to be implemented by engineers - at least because
"Needless to say, including enough fusion fuel to slow an object traveling at these speeds to brake into orbit around Centauri B would require an engine far more efficient and powerful than anything envisioned for Daedalus.".

Or, for a real telescope, use a cluster of ATLAST telescopes in Mars or Venus L2.

[magnemoe]

17 minutes ago, fredinno said:

Or, for a real telescope, use a cluster of ATLAST telescopes in Mars or Venus L2.

You want to put them in the outer solar system to reduce reflected light from various stuff from asteroids to solar wind. 
An cluster is good but again you need lots of mirror areal as you get so few photons. having multiple linked telescopes give you better resolution, it don't increase the sensibility. 

[fredinno]

7 hours ago, magnemoe said:

You want to put them in the outer solar system to reduce reflected light from various stuff from asteroids to solar wind. 
An cluster is good but again you need lots of mirror areal as you get so few photons. having multiple linked telescopes give you better resolution, it don't increase the sensibility. 

Dude, did you see the ATLAST concept? https://en.wikipedia.org/wiki/Advanced_Technology_Large-Aperture_Space_Telescope

LOTS of mirror area.

I doubt you'd be able to carry this to the outer solar system though- that's why I said Mars. Then we can also peer back down on Mars, hopefully.

Edited February 21, 2016 by fredinno

[magnemoe]

4 hours ago, fredinno said:

Dude, did you see the ATLAST concept? https://en.wikipedia.org/wiki/Advanced_Technology_Large-Aperture_Space_Telescope

LOTS of mirror area.

I doubt you'd be able to carry this to the outer solar system though- that's why I said Mars. Then we can also peer back down on Mars, hopefully.

Nice, looks like specifications is good enough to get atmospheric composition, even surface features and rotation rate and that my requirement for this was far to high. 
Putting it at L2 also make it practical to service. 

[Spaceception]

Alright guys, lets get back on track.

[Lhdev]

With the recent progress with laser based fusion the project seems within the realm of possible. The fusion doesn't need to obtain break even,  it just needs to be repeatable and provide thrust.

If Long Shot idea is used with the concept of accelerated fuel then a true interstellar capability might be possible. Pellets of fusion fuel and and uranium pellets can be attached to a RF sail and accelerated to high fraction of speed of light, similar to StarWisp. The RF power beams can be earth based.

https://www.energy.gov/articles/doe-national-laboratory-makes-history-achieving-fusion-ignition

https://en.wikipedia.org/wiki/Starwisp

https://medium.com/our-space/breaking-the-rocket-equation-c078047c0881