/sci/ - Science & Math

[Anonymous No.7134394]

At what point will China surpass the US in terms of space exploration?

[Anonymous No.7134402]

When they build a fully reusable launch system maybe. Or a moon base, or land on Mars, or build a space station with rotating ring.

[Anonymous No.7134411]

>>7134394
has china done anything that's not been done by anyone else before that was only possibly with technology they developed?

[Anonymous No.7134529]

Never. They're copying the expensive expendable heavy lift approach of America but with less money, expertise, and with a start delay. They haven't even started.

[Anonymous No.7134574]

>>7134529
CZ-9/LM-9 is a more a copy of Saturn V than SLS.

There's nothing like SLS. SLS is pure insanity. They forced the designers to use shuttle parts to keep the pork flowing to the shuttle contractors.

LM-9 is using a sensible, conventional kerosene/oxygen booster, like the Saturn V, not a huge hydrogen/oxygen first stage, which makes everything far harder and more expensive.

LM-9 is basically sane, sound, and practical for its intended purpose, like Saturn V was, but about one hundredth as hard to pull off because of half a century of general progress in science and technology.

It's Falcon Heavy that could make LM-9 look bad, with its flyback booster reusability, and the SpaceX Raptor-powered next generation vehicle, which is intended to have a very large payload AND total reusability.

[Anonymous No.7134582]

>>7134574
>but about one hundredth as hard to pull off because of half a century of general progress in science and technology
>completely forgetting about the literal hundreds of thousands of hours that SSMEs have been flown and tested
You're right about Falcon heavy though

[Anonymous No.7134594]

>>7134394

When they can figure out how to pass a Calc I test without cheating, I suppose.

[Anonymous No.7134602]

>>7134594
>mfw you failed Calc I and a bunch of chinks passed while you are here shitposting and complaining about them

[Anonymous No.7134604]

>>7134582
I don't see what the one has to do with the other.

Three problems with the track record of the SSMEs:
1) they're not running them at the same performance as they have experience with, but pushing them beyond their original performance spec,
2) they only have a small inventory of , and will have to replace them with a new expendable variant design to keep costs down, and
3) they're using more than three together on the SLS, and with more powerful solid boosters. They could barely survive a flight with each others' vibrations when it was three of them and the less powerful boosters.

The SSME is a liability. It wasn't designed to be expendable. It wasn't designed for this kind of performance. It wasn't designed for modern fabrication methods. It is primitive and needlessly costly for this application.

[Anonymous No.7134610]

I'm betting on the first Chinese man on the moon having a miserable as fuck facial impression when returning to Earth and during his celebratory parade.

[Anonymous No.7134627]

>>7134604
Aren't the engines on the Delta IV based on the shuttle's?

[Anonymous No.7134637]

>>7134627
No, they were a clean-sheet design, and basically only resemble the SSME in that they're both hydrogen-fuelled. Anyway, Delta IV is the canonical example of why using hydrogen in the booster just makes your rocket more expensive. It was a flop that was only kept alive with occasional flights as a backup to Atlas V.

[Anonymous No.7134669]

>>7134637
>>7134604
You are literally retarded.

Both kerosene and hydrogen have their benefits and their drawbacks. The fact that you think you know more than actual practicing engineers on this subject is rather amusing.

[Anonymous No.7134700]

>>7134669

>appealing to authority in the form of space engineers

space engineers are opinionated, ego and fetish driven, and those opinions differ wildly as does their character.

[Anonymous No.7134708]

>>7134700
>muh appeal to authority
If you've got the the studies to back up your thoughts on why the current SLS configuration is a bad idea then by all means post them.

Otherwise fuck off with your pseudo-intellectualism.

[Anonymous No.7134715]

>>7134669
Engineers didn't make the decision to use the SSME for SLS. That was political.

Hydrogen is a bad choice for a booster. It's difficult to handle, hard to pump, causes material compatibility problems, and has low energy density. You end up building more booster to take the same upper stage and payload to space.

The shuttle used hydrogen because it wasn't a booster, it was the orbital stage. But the SLS is sticking an upper stage on top of the SSME-powered stage. They'd be much better off with a core stage that ran on conventional kerosene fuel, and with liquid-fueled side-boosters, with crossfeed and the same engines.

And the engineers know it. They've just been overruled.

[Anonymous No.7134723]

>>7134708
>studies to back up your thoughts
This is the second-lowest form of internet argument. You're not willing to engage on a rational level, but you want to sound like you're being not only rational, but scientific. So instead of discussing reasons, you demand studies.

[Anonymous No.7134806]

>>7134715
Yeah the SLS certainly won't fly.
It's a political tool not a real rocket. By all standards of measure it will likely get ten feet off the ground and them explode because of those evil hydrogen engines (did you know that hydrogen explodes?)

>Engineers didn't make the decision to use the SSME for SLS. That was political.
They wouldn't be using them at all if it wasn't going to work. They aren't really "reusing the shuttle engines" because they get disposed of every launch under this system, but the average senator doesn't need to know that.

>Hydrogen is a bad choice for a booster. It's difficult to handle, hard to pump, causes material compatibility problems
Well it isn't a booster any more than the shuttle engines were
Did you miss the part where there were two solid propellent motors strapped on the side?

>and has low energy density
Actually, it has higher energy density than kerosene, but a lower specific impulse at low altitudes.

>But the SLS is sticking an upper stage on top of the SSME-powered stage.
The SLS is also built specifically to take large cargo out of LEO. Also I'm not really sure why you're contrasting this to the shuttle, they more or less run the exact same for the first 9 minutes of flight.

>They'd be much better off with a core stage that ran on conventional kerosene fuel, and with liquid-fueled side-boosters, with crossfeed and the same engines.
They could have split the central booster into a kerosene for the first 100000 ft and a hydrogen booster for the suborbital injection, but I suspect they took this route because there's less parts to fail.

>And the engineers know it. They've just been overruled.
There are always engineers who approve and always engineers who think it is the worst idea ever. The fact is that they wouldn't build it if it weren't going to work. They have to play ball for the funding to continue, after all.

[Anonymous No.7134859]

>>7134806
>They wouldn't be using them at all if it wasn't going to work.
Nobody said that it wasn't going to "work" in a narrow technical sense, but this is an absurdly slow and expensive way to develop an underperforming rocket that's going to be obsolete before it flies and too expensive to actually use.

>They aren't really "reusing the shuttle engines" because they get disposed of every launch under this system
They are literally reusing engines taken from the retired fleet of space shuttles.

They only have enough for about four flights, and that's about as long as this farce of a program is likely to last.

The plan is to spend half of the engine supply on test flights. Then, if everything goes well on the first try (which is by no means guaranteed), they get one or two more flights, and then they have to start over with a new engine, requiring more test flights.

And by this point, SpaceX will probably be flying a fully reusable rocket with a bigger payload, flying every week for about $10 million per launch.

SLS is a $40 billion program for four launches and nothing worth having at the end of it. SLS is too wimpy and Orion is to fat for a moon landing or a mission to a near-Earth object, and SLS isn't capable of the launch-rate needed for multi-launch missions.

Constellation was designed for two-launch missions. One Ares I to lift the Orion, and one Ares V to lift the Earth-departure stage. Together, they would considerably outperform the Saturn V, thus enabling a moon landing mission with the four-man Orion capsule, compared to the three-man Apollo mission.

When Constellation was cut down to SLS, which will be considerably less powerful than the Saturn V, the same overweight Orion capsule was kept as the crew vehicle. So it can't go anywhere.

SLS is fucking nuts. It's completely political. A rocket to nowhere.

[Anonymous No.7134872]

>>7134806
>Actually, it has higher energy density than kerosene
Do your homework. It has higher specific energy (energy per unit mass) than kerosene, but much lower energy density (energy per unit volume).

>but a lower specific impulse at low altitudes.
Hydrogen still has a higher specific impulse, regardless of altitude. What it has is lower density impulse, which is more important at low altitudes, when you need lots of thrust (lower density impulse means you have to pump a higher volume of fuel into the combustion chamber, which means heavier, more expensive engines) and when you want to minimize drag (lower density impulse means that your fuel tank is bigger, which makes you push more air).

[Anonymous No.7134900]

>>7134859
>absurdly slow and expensive way to develop
Who said anything about development?
Of course it's slow, given the extremely tight budget that NASA has had (up until a few weeks ago, but it's still a really narrow budget)
>underperforming rocket
How is the largest lift capability ever "underperforming"?
> and too expensive to actually use
government agencies always go overbudget, and a company like space x has no incentive to do exploration
>They are literally reusing engines taken from the retired fleet of space shuttles.
obviously. Why build entirely new manufacturing and processing facilities when the infrastructure is already there?
>and then they have to start over with a new engine, requiring more test flights.
Are you retarded? They're going to build more SSMEs and they will not require full flight tests just to test them.
>And by this point, SpaceX will probably be flying a fully reusable rocket with a bigger payload, flying every week for about $10 million per launch.
and? They do not currently have plans for beyond LEO capabilities.
>SLS is a $40 billion program for four launches and nothing worth having at the end of it.
Only if congress cancels it (like the Democlaps did with constellation)
>SLS is too wimpy and Orion is to fat for a moon landing or a mission to a near-Earth object
There's that "it's not going to work because I said so" jargon again.
>Constellation was designed for two-launch missions. One Ares I to lift the Orion, and one Ares V to lift the Earth-departure stage.
...and so was SLS
They have at least four (4) variants planned all with different missions in mind, including a cargo launch variant. The Ares-1 could only send orion and a short-range SM into LEO anyways.
>When Constellation was cut down to SLS, which will be considerably less powerful than the Saturn V
Objectively false, the SLS puts at least 30,000kg more into LEO.

[Anonymous No.7134903]

>>7134872
Considering that the fuel itself is more heavy than the tank that holds it, mass is more important in this case.

Your argument might hold merit of the SLS was a liquid fuel bottom stage ONLY, but the solid propellent motors provide more than 75% of the total liftoff thrust.

[Anonymous No.7134963]

>>7134900
>>7134903
>Of course it's slow, given the extremely tight budget that NASA has had
You're kidding, right? They've been spending over a billion dollars per year for ten years now (SLS is a continuation, and downgrade, of Constellation). To develop an expendable rocket with capabilities comparable to one they already built half a century ago.

All they had to do was update the Saturn V design for modern materials, guidance systems, and production methods. They actually did most of the necessary work for this, just exploring options for boosters and upper stages for Constellation/SLS. That work will not be used.

Furthermore, they didn't have to develop a vehicle at all. Elon Musk guaranteed that he could develop a 150 ton payload rocket for them for $2.5 billion. ULA made a similar proposal at $5.5 billion. Either would have flown at a far lower per-flight cost than SLS.

NASA wanted to just bid it out. Congress wrote a law requiring them to make their own rocket, and to use shuttle parts, to hell with sane engineering.

>>When Constellation was cut down to SLS, which will be considerably less powerful than the Saturn V
>Objectively false, the SLS puts at least 30,000kg more into LEO.
Are you smoking actual crack? Saturn V could put 120 tons into LEO. The SLS goal, for some distant future fantasy version, which NASA's own people have said will not possibly fly before 2030, is only 10 tons more.

The ACTUAL version of SLS will have a payload ranging from 70-95 tons. Not because this was considered an appropriate goal (it's plainly inadequate for the intended uses of SLS), but because their hands were tied by congress, and this is the best they can with legislators making key engineering decisions on behalf of lobbyists.

[Anonymous No.7134976]

>>7134900
>>They are literally reusing engines taken from the retired fleet of space shuttles.
>obviously. Why build entirely new manufacturing and processing facilities when the infrastructure is already there?
Why am I trying to talk to someone who doesn't know what words like "infrastructure" mean?

>>and then they have to start over with a new engine, requiring more test flights.
>Are you retarded? They're going to build more SSMEs and they will not require full flight tests just to test them.
They aren't going to be the same SSMEs. SSMEs are way too expensive for that. They're designing new engines, which they're calling SSMEs, but aren't really. They will need flight testing before they're safe for manned flights.

Mind you, NASA might go ahead without testing...

[Anonymous No.7134994]

>>7134976
Actually, the second flight planned for SLS is a manned test flight with a new, completely untested upper stage, and sending a crew for a moon flyby only the third time an Orion capsule is in space.

Pretty high probability of crew loss. NASA hasn't learned shit about safety.

[Anonymous No.7135005]

>>7134903
> Your argument might hold merit of the SLS was a liquid fuel bottom stage ONLY,
> but the solid propellent motors provide more than 75% of the total liftoff thrust.

Good point.

[Anonymous No.7135029]

>>7134859
> Constellation was designed for two-launch missions. One Ares I to lift the Orion, and one Ares V to lift the Earth-departure stage.
> Together, they would considerably outperform the Saturn V, thus enabling a moon landing mission with the four-man Orion capsule,
> compared to the three-man Apollo mission.
> When Constellation was cut down to SLS, which will be considerably less powerful than the Saturn V, the same overweight Orion capsule
> was kept as the crew vehicle. So it can't go anywhere.

This is reasoning with the "law of the excluded middle".
So like a small Ares and a big Ares are perfect, but an inbetween Ares - SLS, is a worthless rocket to nowhere.

[Anonymous No.7135038]

>>7135005
It's not like the solid boosters are a good design choice. Again, it's just congress forcing NASA to keep shoveling money to the shuttle contractors.

The solid boosters have good density impulse, but poor specific impulse, are difficult to handle on the ground (the crawler-transporter needed a major upgrade for SLS, which wouldn't have been necessary if they had switched to liquid boosters, which can be transported empty and fuelled on the pad), are dangerous for ground crew and for vehicle crew, and are more expensive than liquid-fuelled boosters.

There is basically no advantage to them. For the space shuttle, they were considered easier to make reusable, but the SLS boosters will not be reused.

[Anonymous No.7135041]

>>7134976
> They're designing new engines, which they're calling SSMEs, but aren't really.
> They will need flight testing before they're safe for manned flights.
> Mind you, NASA might go ahead without testing...

Is there any doubt that with many decades of rocket motor technology development and numerous successfull engine designs to draw from
and with modern advances in material science and such, that a new reliable cost effective engine can be realized to power the SLS ?

[Anonymous No.7135043]

>>7134394
Anytime you see two rival countries with the words surpass in the sentence,it's a /pol thread.

[Anonymous No.7135053]

>>7135029
>This is reasoning with the "law of the excluded middle".
That's not what that means. Look it up, for christ's sake.

>So like a small Ares and a big Ares are perfect, but an inbetween Ares - SLS, is a worthless rocket to nowhere.
That's a small Ares PLUS a big Ares for each mission. SLS isn't a compromise between the Ares I and Ares V, it's strict and major downgrade of Ares I+V.

The Orion capsule was DESIGNED FOR Ares I+V with 215 tons payload. That means it's too heavy to go anywhere interesting on SLS, with 70-95 tons payload.

Ares I was also going to enable much more extensive testing of Orion, and use of it as a crew rotation vehicle for the ISS. Orion was going to be proven in LEO before being sent any further out. If things go wrong in LEO, you can initiate re-entry pretty quickly. You really want to spend some time in LEO with a crew capsule before you use it anywhere else.

Now NASA paying for the development of three crew capsules at once, and has no intent or plan for reasonable testing of Orion so it can safely carry astronauts beyond LEO.

Constellation wasn't a good program either. SLS is just the same program with the last semblance of sanity cut out.

[Anonymous No.7135064]

>>7135041
>Is there any doubt that with many decades of rocket motor technology development and numerous successfull engine designs to draw from and with modern advances in material science and such, that a new reliable cost effective engine can be realized to power the SLS ?
None of that stuff is an excuse from actual flight testing.

And yes, when you assign a government bureaucracy to design a complicated piece of technology, there is always doubt that it will work, and especially that it will work within a budget and timeframe to be relevant when complete.

[Anonymous No.7135084]

>>7135038

> It's not like the solid boosters are a good design choice.
You give some reasons below. But it's not like liquid fueled boosters don't have negatives also.

> Again, it's just congress forcing NASA to keep shoveling money to the shuttle contractors.
Politics is always involved. They did spend a lot of time and money improving those boosters over the years.

> The solid boosters have good density impulse, but poor specific impulse
They work good though.

> are difficult to handle on the ground
So is LOX.

> the crawler-transporter needed a major upgrade for SLS which wouldn't have been necessary
All that infrastructure was due for rennovation anyway.

> if they had switched to liquid boosters which can be transported empty and fuelled on the pad
Has there been a major ground disaster ?

> are dangerous for ground crew and for vehicle crew
All rocket fuel technology is potentially dangerous.

> and are more expensive than liquid-fuelled boosters.
Sure if you compare 70's shuttle booster development costs to SpaceX new liquid boosters.
But newer liquid boosters actually rely on decades of former development costs.

> There is basically no advantage to them.
Other than being simple and powerful.

> For the space shuttle, they were considered easier to make reusable
In other words: superior in reliability.

> but the SLS boosters will not be reused.
They could be recovered if needed.

[Anonymous No.7135123]

>>7134394
Uncertain.
The US has some interesting developments occurring at NASA and in the private sector.
China has more people and is very interested in technology these days.

[Anonymous No.7135125]

>>7135084
>> if they had switched to liquid boosters which can be transported empty and fuelled on the pad
>Has there been a major ground disaster ?
Yes, but you missed the point. Empty liquid boosters are far lighter, and therefore far easier to transport. They're bulky, but they're not massive, and you can bring the fuel to the pad tanks by the truckload. Conventional commercial transportation is cheap, fast, and reliable.

>> and are more expensive than liquid-fuelled boosters.
>Sure if you compare 70's shuttle booster development costs
Development costs don't come into it. You can disregard the solid booster development costs, and include the liquid booster development costs, and the solid boosters will still be more expensive.

They're only cost effective when you use small ones, and even then it's kind of questionable. Notice that the cost-conscious Russians don't bother with them, and neither does SpaceX.

>> For the space shuttle, they were considered easier to make reusable
>In other words: superior in reliability.
You're just making shit up. No, not superior in reliability. Easier to develop into a reusable form.

A solid rocket motor is naturally a robust structure. The refuelling process is practically a remanufacturing one. So it's easy to have it survive impact with the water and say, "Look, we recovered it, and we're reusing it!" and then take it into a factory and make a new rocket of it.

With a high thrust and short burn time, it also landed a shorter distance down range, which was important for recovering it.

Remember that the solid rocket boosters are what caused the Challenger disaster. And there have been similar blowups with other solid rocket boosters. No, they weren't superior in reliability.

[Anonymous No.7135130]

if each chinaman stood on another's shoulders, they could easily reach the moon

[Anonymous No.7135171]

>>7135125
> You can disregard the solid booster development costs, and include the liquid booster development costs, and the solid boosters will still be more expensive
The actual costs depend on so many complicated factors. Why should this be inherently true ?

Just the refueling issue alone cannot be the answer, since coupling the booster prep to launch assembly process can eliminate the need for transporting
rocket shells all over the nation.

> No, not superior in reliability.
> Remember that the solid rocket boosters are what caused the Challenger disaster.
> And there have been similar blowups with other solid rocket boosters.
> No, they weren't superior in reliability

You are talking about specific examples of solid booster design in an era of pioneering new technology.
That argument alone seems not enough to obsolete solid booster technology.

> A solid rocket motor is naturally a robust structure
Right, so a properly evolved solid booster may indeed be more reliable overall than a liquid fueled booster of the same power.
Now if you take an specific solid design with some problems then sure some other specific liquid variant may outperform it.

There are a lot of complicated tradeoffs comparing solid vs liquid.

[Anonymous No.7135173]

>>7134394
NEVER OP. Look at What the US is doing, satellites watching climate, oceans, sun, eearth, mars, even outside the fucking solar system. The US is rocking it, and always is/will. Go USA ( from a Brit).

Pic related, THIS is the reality of Chinese manufacture.

[Anonymous No.7135195]

>>7135171
>Why should this be inherently true ?
Liquid-fueled rockets obviously have more potential to be cheaper at the large scale. They're simply tanks full of cheap fuel, with a little complicated bit at the end. A solid-fuel rocket still needs a complicated bit at the end, if you want it to fly in the direction of your choice, but the entire tank is also a combustion chamber, and the fuel is much more expensive and must be put in place by a manufacturing process rather than simply tanking up, plus the specific impulse is far inferior.

In practice, it's just the way the industry has worked out that solids are a more expensive way to get impulse. You can research, theorize, or fantasize all you want about it, but regardless of the detailed reasons, that's the actual situation.

>> A solid rocket motor is naturally a robust structure
>Right, so a properly evolved solid booster may indeed be more reliable overall than a liquid fueled booster of the same power.
Again, this is just making shit up. A robust structure doesn't imply greater reliability. It needs that robustness to contain the huge region of unstable combustion within the mass of propellant that is a mix of fuel and oxidizer capable of detonating.

[Anonymous No.7135198]

>>7135125
> They're only cost effective when you use small ones, and even then it's kind of questionable.
> Notice that the cost-conscious Russians don't bother with them, and neither does SpaceX

Testing costs and testing facilities factor in here.
To properly test a large solid rocket booster you pretty much build it and let it burn out.
Liquid fueled engines can be finessed with short or long burn tests with as little or as much fuel as you want for the test.
In the case of shuttle booster technology, all of that development has been done.

[Anonymous No.7135202]

>>7135195
> A robust structure doesn't imply greater reliability

I've never heard anyone suggest we make our rocket hulls as thin as possible for more reliability.

[Anonymous No.7135212]

>>7135198
>In the case of shuttle booster technology, all of that development has been done.
I'm sorry, do you mean it had all been done before Challenger?

Or do you mean it had all been done before they decided to use it for the Ares I, and the test flight showed a thrust oscillation that they hadn't expected, proving that people couldn't fly on Ares I any time soon?

Or do you mean it had all been done before they decided to add another segment to increase the impulse for SLS, taking the specifications outside of their experience with the shuttle program?

>Testing costs and testing facilities factor in here.
...and regardless of these, large solid rocket boosters cost more to manufacture than liquid-fueled ones. And never mind how much more they also cost to test, transport, and handle at the launch site.

[Anonymous No.7135223]

>>7135202
You can't seriously be this stupid.

The structure has to be more robust because it has to contain a fucking explosion through the full length of the motor.

It's not a higher safety factor. If anything, solid boosters are always riding closer to catastrophic failure.

Do I need to spell it out for you? The solid booster could have a more massive casing than a liquid-fueled rocket and still blow up every time because the wall is too thin.

It NEEDS the additional mass just to hold itself together against its internal forces while operating, so it doesn't provide greater reliability compared to a system that doesn't put its whole structure under such stress during operation.

[Anonymous No.7135229]

>>7135212
Once again you are arguing specifics here. In the long run solid vs liquid is debatable.
Will liquid boosters completely obsolete solid booster firecrackers waiting to explode from sloppy ground handling ?
Will new techniques for solid boosters obsolete less structurally robust more complex liquid boosters ?

[Anonymous No.7135232]

>>7135223
Just one example:
As long as the full hull pressure burn structural strength is adequately engineered,
then the empty portion is less likely to have a catastrophic hull fracture from supersonic buffeting.

[Anonymous No.7135236]

>>7135229
>Will new techniques for solid boosters obsolete less structurally robust more complex liquid boosters ?
No. They won't. That's obvious.

Why? Because we're getting reusable liquid-fuelled rockets. And because there's never going to be a solid propellant that approaches the low cost of liquid propellants.

Stop trying to defend the ridiculous throwback technology of the SLS.

[Anonymous No.7135251]

>>7135236
> And because there's never going to be a solid propellant that approaches the low cost of liquid propellants
If you have any real world figures handy, drop them in one of your posts.
I know at the rate most nations launch rockets, this cost is somewhat irrelevant.

[Anonymous No.7135260]

>>7135212
> Or do you mean it had all been done before they decided to add another segment to increase the impulse for SLS,
> taking the specifications outside of their experience with the shuttle program
This is a valid point of worry since another segment changes all the stresses.
But that does not mean they won't be able to have sufficient confidence in it.

> test flight showed a thrust oscillation that they hadn't expected, proving that people couldn't fly on Ares I any time soon
Not familiar with this story, but could'nt a liquid booster have a similiar problem after years of costly development ?