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NASA Announces Design for New Deep Space Exploration System

nasa.gov

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Re: NASA Announces Design for New Deep Space Exploration System

#61

Post by bfe »

zrail wrote: post #6

If SpaceX and friends can reliably launch cargo and eventually humans into LEO, why can't NASA focus on what to put into space, rather than how to get there? I'm sure I don't understand the mechanics of it, but wouldn't it be possible to put up a few smaller cargo carriers containing fuel and pieces of a trans-mars ship and assemble it in orbit?

It's still much cheaper and easier in the long run to build one launcher big enough to do a straight shot from Earth to Mars or other target. You have all the assembly done on Earth and put all the lift capability into a single hyperbolic trajectory straight to the target, instead of doing on-orbit assembly (which we know how to do but is still outrageously harder) and devoting a lot of launch capability into putting mass in a circular orbit in an orbital plane around the Earth that's constrained by the launch site latitude, only to have to counteract a lot of that Delta V to put that mass onto a new hyperbolic escape trajectory along a plane defined between Earth and the target once it's put together.

I believe SpaceX is planning on developing a still more powerful heavy launch rocket that could shoot human crewed missions straight to Mars in a single shot. The Falcon Heavy could send a substantial payload to the Mars surface.

Re: NASA Announces Design for New Deep Space Exploration System

#62

Post by dkokelley »

nknight wrote: post #49

I have a sophisticated layman's understanding of stuff like orbital mechanics, launch energies, etc., but one thing I've never been entirely sure of: Why are rockets always round? I'm guessing it's the least-questions-asked shape as far as aerodynamics goes, and gives good weight efficiency assuming you can build what you need into a round shape. Is there anything more fundamental than that?

I suspect weight and aerodynamics play the most important part in determining shape. What I've always wondered is why we've never effectively used wings on our spacecraft to get part of the way there. Spaceship one used something like this with its "stage 1" vehicle.

I haven't done the math, but I always assumed it would be less expensive (as in fuel and weight) to start the orbital boosters from 50,000ft after climbing via traditional wings, as opposed to the brute force option of simply producing as much thrust as possible and climbing straight up.

Granted for extremely large payloads the structural requirements for building wings that can support the weight might be impractical, but wouldn't it have been easier for the space shuttle to "launch" from 50,000ft?

Re: NASA Announces Design for New Deep Space Exploration System

#63

Post by gaius »

nknight wrote: post #49

I have a sophisticated layman's understanding of stuff like orbital mechanics, launch energies, etc., but one thing I've never been entirely sure of: Why are rockets always round? I'm guessing it's the least-questions-asked shape as far as aerodynamics goes, and gives good weight efficiency assuming you can build what you need into a round shape. Is there anything more fundamental than that?

Because it makes sense for any pressure vessel to be round.

Re: NASA Announces Design for New Deep Space Exploration System

#64

Post by ars »

coderdude wrote: post #30
nostromo wrote: post #26

Earlier quoted context omitted.

A guess: it's because it's easier to spot damage, dust, debris, etc.

Also, in a vacuum does white still absorb the least amount of heat energy from light?

The rocket part doesn't go into orbit, only the nose.

Re: NASA Announces Design for New Deep Space Exploration System

#65

Post by csomar »

HeyLaughingBoy wrote: post #55
sliverstorm wrote: post #33

Earlier quoted context omitted.

It's a symptom of the times. People don't care about science today, they care about jobs, and NASA is trying to play that tune to keep themselves afloat.

When have people never cared about jobs? When have they (outside a select few) ever really cared about Science?

When joblessness is 3% and you can (not easily) find a job if you get fired from another, landing to the moon is quite interesting for you, and for anyone else.

When you are struggeling to pay the bills, finding a job, or securing your current job, landing to the moon is a quite stupid thing the USA gov. is spending the money on.

Although it won't cost the US economy only a little (few billions) comparing to its size, people won't be easy with it. They are in trouble living in earth, and are not looking for the moon or massively expensive explorations.

Re: NASA Announces Design for New Deep Space Exploration System

#66

Post by EREFUNDO »

VladRussian wrote: post #54
EREFUNDO wrote: post #42

The Chinese explored the Middle East and Africa almost 100 years before the Europeans. Every expedition consisted of 300 ships, some as long as 400 feet with 9 mast and an armada crew totaling 28,000 men. After 30 years of doing it they realized that they were spending too much money on these grand expeditions. The succeeding emperor ended the program. The Europeans on the other hand would send out just a few ships a…

it can be turned the other way as well - Chinese fell into stagnation and lost the technological, power and all other races during last 2-3 centuries because they stopped the exploration and closeted themselves inside their kingdom. >We stopped the moon landings for the same reason the Chinese stopped landing Eunuchs in Africa. and we don't go to Mars and beyond for the same reason Chinese didn't venture deep into an…

I agree. The emperor who replaced Zhu Di was more conservative and thought that China should close its doors. He famously said that "The outside world had nothing to offer China, it is too primitive and backwards, leave it alone." This inward looking mentality, fueled by the belief in your own superiority, is the disease of great powers. I am afraid that in some ways the United States has become one, maybe it's a good indicator of a power in decline.

Re: NASA Announces Design for New Deep Space Exploration System

#67

Post by InclinedPlane »

nknight wrote: post #49

I have a sophisticated layman's understanding of stuff like orbital mechanics, launch energies, etc., but one thing I've never been entirely sure of: Why are rockets always round? I'm guessing it's the least-questions-asked shape as far as aerodynamics goes, and gives good weight efficiency assuming you can build what you need into a round shape. Is there anything more fundamental than that?

The roundness is mostly due to the fact that propellant almost always requires being stored in a pressure vessel, more so for cryogenic propellants. It's far, far easier to make a pressure vessel that's at least axisymmetric. Thus, the fuel tanks tend to be spheres or cylinders. And since the fuel tanks are by far the largest components of launch vehicles the rocket itself tends to be cylindrical.

Re: NASA Announces Design for New Deep Space Exploration System

#68

Post by drzaiusapelord »

hga wrote: post #50
drzaiusapelord wrote: post #37

Earlier quoted context omitted.

Call me when dragon has gone to space as many times as the shuttle and we'll compare safety records, thanks.

Nope, long before it first launched we knew the Shuttle was a shoddy design: The SRBs saved money on development but are very bad for human flight, you want engines you can turn off. The insane fragile tile and leading edge heat protection, all to satisfy a "requirement" the Air Force didn't care about, a Vandenburg single orbit polar mission (to return to the same spot on Earth while it's rotated under you requires…

I'm aware of the shuttles limitations and the politics behind them, but the Soyuz system isn't any safer. I'm just skeptical of this sudden "ZOMG DRAGONX SAFETY WILL BE AWESOME" assumption that so many pro-privatization types seem to have. Considering how many times their rockets have blown up already perhaps its best to be not drawing any conclusions thus far.

Re: NASA Announces Design for New Deep Space Exploration System

#69

Post by EREFUNDO »

EREFUNDO wrote: post #66
VladRussian wrote: post #54

Earlier quoted context omitted.

it can be turned the other way as well - Chinese fell into stagnation and lost the technological, power and all other races during last 2-3 centuries because they stopped the exploration and closeted themselves inside their kingdom. >We stopped the moon landings for the same reason the Chinese stopped landing Eunuchs in Africa. and we don't go to Mars and beyond for the same reason Chinese didn't venture deep into an…

I agree. The emperor who replaced Zhu Di was more conservative and thought that China should close its doors. He famously said that "The outside world had nothing to offer China, it is too primitive and backwards, leave it alone." This inward looking mentality, fueled by the belief in your own superiority, is the disease of great powers. I am afraid that in some ways the United States has become one, maybe it's a goo…

The eventual decline and stagnation was the effect of the decision to close China's doors. But the cause of the end of the expeditions was largely financial. Culture also has an important role to play. The Chinese were not looking for new lands or have any interest in converting people to their religion. They were looking for respect and recognition. They want to prove to the world that China is the undisputed power on Earth and that they are the pinnacle of civilization. They could not have imagined that the world is about to enter into a period of tremendous change so they felt no reason to change their imperial system. How can you change perfection? ...LOL

Re: NASA Announces Design for New Deep Space Exploration System

#70

Post by VladRussian »

EREFUNDO wrote: post #69
EREFUNDO wrote: post #66

Earlier quoted context omitted.

I agree. The emperor who replaced Zhu Di was more conservative and thought that China should close its doors. He famously said that "The outside world had nothing to offer China, it is too primitive and backwards, leave it alone." This inward looking mentality, fueled by the belief in your own superiority, is the disease of great powers. I am afraid that in some ways the United States has become one, maybe it's a goo…

The eventual decline and stagnation was the effect of the decision to close China's doors. But the cause of the end of the expeditions was largely financial. Culture also has an important role to play. The Chinese were not looking for new lands or have any interest in converting people to their religion. They were looking for respect and recognition. They want to prove to the world that China is the undisputed power…

>Culture also has an important role to play. The Chinese were not looking for new lands or have any interest in converting people to their religion.

Bingo. Gene Roddenberry's genius is replacing the classical humans' violence fueled drivers of "new lands or ... interest in converting people to their religion" with "to explore new worlds, to seek out a new life, and new civilizations" :) I hope that he will eventually be proven right.

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