The Astronomy Thread

Cybsled · Jul 12, 2021

same reason we don’t have a moon base: just because something is cool, doesn’t mean it is economically practical

Gavinmad · Jul 12, 2021

IMO the next major advancement in space travel is more likely to be infrastructural, not technological.

BrutulTM · Jul 12, 2021

Mudcrush Durtfeet said:
Technology does some amazing things, but not always.

Fusion power is stil 1234567 years away and where are all the flying cars? We still need roads. :-(

Yeah it's probably more accurate to say that history hasn't been kind to people who make long term predictions, whether they are optimistic or pessimistic.

Tuco · Jul 12, 2021

Gavinmad said:
IMO the next major advancement in space travel is more likely to be infrastructural, not technological.

Can get hard to differentiate between that. Biggest achievement for spacex will either be their two stage starship landing both stages and then orbital refueling. Both are huge tech and infrastructure gains. The infrastructure they're building for the starship production is incredible.

Burns · Jul 12, 2021

Oldbased said:
I mean, what VG has right now is probably what, 100 seconds of burn from doing it and most of that isn't needed to get to space but rather achieve velocity to match what would already be in space going at speeds to sustain itself for long periods of time. It isn't much but as stated is still so far far away. It all comes down to engine tech. Something like a stable heat reactor that people don't mind flying over them producing decent trust without a heavy fuel load.

My point is there are many many things people said in my lifetime isn't possible or couldn't be done with our current tech that not only were possible but they did it so damn well it became cheap so to speak.

It's not likely to happen but tomorrow a chemical compound could be discovered that cures every illness and disease known to man.
So on and so on.
We don't know what tomorrow brings, but with so many space agencies out there not bogged down by politics now, chances are there will be new and interesting discoveries because we know the problems and it only takes dreamers to find the solutions.
The main reason pretty much jack shit happened the past 50 years in space is because we left it up to govs to decide our fates.

I'm certain Elon told VG they could supersize all the shit and reach higher goals but that costs more. Much more and their thing is reaching the US version of space for low ticket prices and a few hundred K is cheap as far as space goes, but as they gain knowledge and data, as newer materials become stronger, lighter and more affordable, as propulsion becomes more advanced ( Even SpaceX Raptors get more and more powerful, use less fuel and become more reliable just even this year in version changes ) that stretch goal slowly becomes more and more real.

It's funny, when it is a business, space tech gets better and cheaper, whereas when it is gov business spending someone elses's money little to no improvements are made.

I'll make a nice harmless bet. We'll hit back on this very post in just 10 short years. I 100% guarantee you something amazing has happened as far as how we handle space or tech by that time. If not, I will custom build you something nice out of oak, hickory or walnut.

The vast majority of technology is iterative, not revolutionary, so ten years doesn't seem like that much time for an "amazing" technology, something the likes of no experts can currently think of, but sure, maybe. If I were a betting man, I would say that it is far more likely to happen in the field of space habitation than a more effective way to leave the atmosphere, though.

Burns · Jul 12, 2021

Mudcrush Durtfeet said:
Space Elevators off Earth are NOT on the horizon.

I guess I chose the wrong words, I was thinking more along the lines of it is the only alternative I have seen to rocket power that may work and have all of its (many) problems resolved within the next 100 years.

Mudcrush Durtfeet · Jul 12, 2021

Burns said:
I guess I chose the wrong words, I was thinking more along the lines of it is the only alternative I have seen to rocket power that may work and have all of its (many) problems resolved within the next 100 years.

Anything (more or less) might be resolved in 100 years, lol. That's not saying anything meaningful.

Right now, there is no path to making a space elevator. It seems to be impossible by any reasonaable improvement in technology in the next twenty years or so.

There are other possible alternatives to rocket power to orbit. A very large cannon or a magnetic rail gun type arrangement have been proposed. I think the gun is actually possible by today's technology but I could be wrong. There are issues with rail guns but maybe.

Other than that, nothing really comes to mind.

Mudcrush Durtfeet · Jul 12, 2021

That being said, nuclear powered rockets are an obvious thing that *could* be developed that would take us beyond what is possible with chemical rockets. There are issues.

Otherwise, the only space tech that is reasonably capable of taking us to the other planets in a remarkably cheaper and more reliable way is being developed by SpaceX. The plan is to make a rapidly reusable super heavy lift vehicle. Consider that it will make the Falcon 9 look like a toy. It's going to be amazing.

Cybsled · Jul 12, 2021

The next big revolution is already happening: reduction in costs to bring payloads to space. Everything else will springboard off that. It's the same as with railroads and air travel - once you figure out the costs of infrastructure and platform, and get those to reasonable levels, then it opens up all sorts of industry that otherwise would not have been able to take advantage of that, or even exist without that.

Burns · Jul 12, 2021

Mudcrush Durtfeet said:
Anything (more or less) might be resolved in 100 years, lol. That's not saying anything meaningful.

Right now, there is no path to making a space elevator. It seems to be impossible by any reasonaable improvement in technology in the next twenty years or so.

There are other possible alternatives to rocket power to orbit. A very large cannon or a magnetic rail gun type arrangement have been proposed. I think the gun is actually possible by today's technology but I could be wrong. There are issues with rail guns but maybe.

Other than that, nothing really comes to mind.

Some years back I read an article (or maybe it was a TED talk or the new Cosmos show) about rocket alternatives to put things in orbit (I just tried to find it, with no luck). From what I recall, in order to reach orbit, through cannon or rail gun, it would require acceleration so fast that the gravitational forces would easily rip a human apart, and even damage some inorganic payloads. It also talked about how earth's gravity is rather close to being too strong for any kind of rocket to escape it, at all.

Looks like this Skyhook could be a hybrid alternative that uses rockets to get to the edge of space and a tether to get farther out. I haven't looking into it, other than the following video, so I don't know much about it.

Kharzette · Jul 12, 2021

Propulsion without propellant is the only way we are going to get anywhere interesting.

Big Phoenix · Jul 12, 2021

Mudcrush Durtfeet said:
I think the gun is actually possible by today's technology but I could be wrong.

Already been done. They used 16 inch cannons from Iowa class battleships in their testing;

Project HARP - Wikipedia

en.wikipedia.org

Burns said:
From what I recall, in order to reach orbit, through cannon or rail gun, it would require acceleration so fast that the gravitational forces would easily rip a human apart, and even damage some inorganic payloads.

Pretty much, see the above about HARP. Not only are the gforces monumental, but the payload capacity is incredibly small both in size and weight.

Ideally a similar system or a mass driver on the moon would be amazing. You could build a massive track or gun which would allow much more gentle acceleration. Also no pesky atmosphere to deal with burning you up as youre getting into orbit.

Kharzette said:
Propulsion without propellant is the only way we are going to get anywhere interesting.

Nah, nuclear rockets would work well. 800-900 isp v 400-450 isp of chemical rockets with theoretical designs up to 2000 isp or more. Problem is well, the left vehemently opposes anything nuclear.

Mudcrush Durtfeet · Jul 12, 2021

Tuco said:
Can get hard to differentiate between that. Biggest achievement for spacex will either be their two stage starship landing both stages and then orbital refueling. Both are huge tech and infrastructure gains. The infrastructure they're building for the starship production is incredible.

The practical rocketry improvements SpaceX has incorporated is huge. I cannot possibly think of them all, but off the top of my head, you have engines that are cutting edge efficiency (full flow/full cycle), engines that you can throttle and turn on and off many times, large improvements in how quickly they can repeat launch things, being able to reuse rockets at all, their in house production of most of the rocket parts.

Mudcrush Durtfeet · Jul 13, 2021

Big Phoenix said:
Already been done. They used 16 inch cannons from Iowa class battleships in their testing;

Project HARP - Wikipedia

en.wikipedia.org

Pretty much, see the above about HARP. Not only are the gforces monumental, but the payload capacity is incredibly small both in size and weight.

Ideally a similar system or a mass driver on the moon would be amazing. You could build a massive track or gun which would allow much more gentle acceleration. Also no pesky atmosphere to deal with burning you up as youre getting into orbit.

Nah, nuclear rockets would work well. 800-900 isp v 400-450 isp of chemical rockets with theoretical designs up to 2000 isp or more. Problem is well, the left vehemently opposes anything nuclear.

One thing that has been brought up by SpaceX is that there's more to rocketry than just using the hypothetical most efficient parts and so on. One reason (if I recall) that they didn't go with Hydrogen / Oxygen is that though it's a very good reaction for rockets you lose a lot of that in the extra complexity of the rocket, and it's a lot more expensive.

I imagine a nuclear rocket is going to be a lot more expensive overall and more complex with the problem of what to do if the thing crashes and spills radioactive wreckage all over the crash site.

You can say 'just operate them outside of Earth orbit' which solves that issue, but there's no infrastructure to support such a thing right now. Maybe some day.

Mudcrush Durtfeet · Jul 13, 2021

Burns said:
Some years back I read an article (or maybe it was a TED talk or the new Cosmos show) about rocket alternatives to put things in orbit (I just tried to find it, with no luck). From what I recall, in order to reach orbit, through cannon or rail gun, it would require acceleration so fast that the gravitational forces would easily rip a human apart, and even damage some inorganic payloads. It also talked about how earth's gravity is rather close to being too strong for any kind of rocket to escape it, at all.

Looks like this Skyhook could be a hybrid alternative that uses rockets to get to the edge of space and a tether to get farther out. I haven't looking into it, other than the following video, so I don't know much about it.

No. This is so far beyond our current capabilities you might as well be talking about warp drives.

Big Phoenix · Jul 13, 2021

Mudcrush Durtfeet said:
I imagine a nuclear rocket is going to be a lot more expensive overall and more complex with the problem of what to do if the thing crashes and spills radioactive wreckage all over the crash site.

Theyre just nuclear reactors that are cooled by liquid hydrogen rather than water, theyre not anything exotic. We built and operated a few prototypes already and was all set to send them into space for use in a mission to Mars in the 70s until it was canceled in favor of the idiotic Space Shuttle.

NERVA - Wikipedia

en.wikipedia.org

Cybsled · Jul 13, 2021

Wouldn't the coolant being liquid hydrogen unto itself be an issue, though, with the extreme cryogenic requirements? In other words, it would have to be topped off after a long journey?

Mudcrush Durtfeet · Jul 13, 2021

Big Phoenix said:
Theyre just nuclear reactors that are cooled by liquid hydrogen rather than water, theyre not anything exotic. We built and operated a few prototypes already and was all set to send them into space for use in a mission to Mars in the 70s until it was canceled in favor of the idiotic Space Shuttle.

NERVA - Wikipedia

en.wikipedia.org

Those prototypes were NOT actual rocket engines from what I recall. The project was cancelled at the time due to the projected expense dwarfing the Apollo program.

Big Phoenix · Jul 13, 2021

Mudcrush Durtfeet said:
Those prototypes were NOT actual rocket engines from what I recall.

Looks like a fairly complete prototype here;

Can also take wiki with a grain of salt;

The second NERVA engine, the NERVA XE, was designed to come as close as possible to a complete flight system, even to the point of using a flight-design turbopump. Components that would not affect system performance were allowed to be selected from what was available at Jackass Flats to save money and time, and a radiation shield was added to protect external components.[87] The test objectives included testing the use of ETS-1 at Jackass Flats for flight engine qualification and acceptance.[88] Total run time was 115 minutes, including 28 starts. NASA and SNPO felt that the test "confirmed that a nuclear rocket engine was suitable for space flight application and was able to operate at a specific impulse twice that of chemical rocket system."[89] The engine was deemed adequate for Mars missions being planned by NASA. The facility was also deemed adequate for flight qualification and acceptance of rocket engines from the two contractors.[89]

The final test of the series was XE Prime. This engine was 6.9 meters (23 ft) long, 2.59 meters (8 ft 6 in) in diameter, and weighed approximately 18,144 kilograms (40,001 lb). It was designed to produce a nominal thrust of 246,663 newtons (55,452 lbf) with a specific impulse of 710 seconds (7.0 km/s). When the reactor was operating at full power, about 1,140 MW, the chamber temperature was 2,272 K (2,000 °C), chamber pressure was 3,861 kilopascals (560.0 psi), and the flow rate was 35.8 kilograms per second (4,740 lb/min), of which 0.4 kilograms per second (53 lb/min) was diverted into the cooldown system.[1] A series of experiments were carried out between of 4 December 1968 and 11 September 1969, during which the reactor was started 24 times,[86] and ran at full power for 1,680 seconds.[1]

Cybsled said:
Wouldn't the coolant being liquid hydrogen unto itself be an issue, though, with the extreme cryogenic requirements? In other words, it would have to be topped off after a long journey?

The Hydrogen isnt actually coolant, its the fuel. Could have said it better but meant the nuclear reactor in nuclear rockets isnt all that different from a power reactor. Difference is you run liquid hydrogen through it to turn it into super heated gas for exhaust v running water through a power reactor. Just different plumbing.

Though Im not sure what happens after nuclear rocket is done firing to deal with the residual heat. In that video of a hypothetical mission to Mars it looks like they only use each engine for one burn then discard. Von Braun's idea post apollo was using nuclear powered "tugs" to do all the moving in space, reusing them over and over.

Tuco · Jul 13, 2021

The EmDrive is the only way we're going to get to Alpha Centauri. Just a matter of time before it's put into production by Dr. Shawyer.

I built a prototype and use it to power my car.

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