Slashdot is powered by your submissions, so send in your scoop

 



Forgot your password?
typodupeerror
Polls on the front page of Slashdot? Is the world coming to an end?! Nope; read more about it. ×

Comment: Re:What's up with that motor? (Score 5, Interesting) 110

by lourd_baltimore (#49724227) Attached to: Robotic Space Plane Launches In Mystery Mission This Week

There is some speculation that the AR2-3 may not be the engine used in current flights (see other replies to you post).

However, the AR2-3 is human rated. The X-37 is nominally unmanned, but hey the missions are classified, and because Halo Orbital Drop Shock Troopers. Of course some of the alternative engines you mentioned have been used on stages of previous manned flights and are thus presumably man-rated as well.

I did some Binging on the AR2-3 and found a NASA/Rocketdyne/OSC presentation that looks to be drafted around 2000.

Here that seem to make the case high test peroxide (HTP) technologies are the way of the future for upper stage propulsion:

Hydrogen peroxide was selected over liquid oxygen because it is dense, storable, capable of tolerating months in orbit, and meets safety restrictions for being part of the payload in the Space Shuttle.

Of course the Shuttle aspect is no longer a factor, but the other factors still seem to be in play.

Further into the paper, the USFE 10k peroxide motor is mentioned as a project to develop new HTP technologies. These technologies would be used for future HTP-based upper stages. They even have a goal of over 100 uses of an engine before it has to be removed for overhaul. Is that a lot in the world of rockets? As this paper was drafted around 2000 I would guess that the X-37 is using something a bit different that the bog-standard AR2-3 or has moved away from HTP technologies altogether.

Now to say that rocket science has moved away from HTP is not quite true. I don't think there are any big HTP engines used in lower stages. However, the Bloodhound SSC is using a HTP hybrid motor they are designing.

There is also research in to using HTP as a monopropellant for thrusters using a catalytic bed. I suppose the advantage here is that you have HTP as your oxidizer for an upper stage and then it can be used for maneuvering once on orbit. Similar, as you mentioned, to UDMH.

Take a look at the Introduction from the ESA paper referenced above. They cite several reasons why HTP is desirable and advantageous. Cost and safety being paramount. They also mention that Soyuz has been using HTP in its maneuvering systems for over 40 years. I think that HTP safety concerns have been effectively mitigated from the "explode because you looked at it funny" era.

As for performance it seems that HTP is as good as some other technologies, but it's no dog either and it seems to be a good fit for the X-37 or other small stages. Quote from the ESA paper:

The propulsive performance of hydrogen peroxide monopropellant rockets is about 20% lower than hydrazine, but the volume specific impulse achievable with 90% H2O2 is higher than most other propellants due to its high density. This is particularly useful for systems with significant aerodynamic drag losses and/or stringent volume constraints. With respect to bi-propellant and hybrid rocket engines, hydrogen peroxide yields a specific impulse comparable to other liquid oxidizers like dinitrogen tetroxide, nitric acid and even liquid oxygen..

It seems that HTP has many uses and rocket science has not moved away from HTP, indeed, it is being actively researched. It may or may not be used on the X-37 right now. It may or may be used on the X-37 in the future. With further attention to cost, safety, and, increasingly, environmental impact, HTP seems to be coming for you...

Comment: Re:Wow, a whole $10 million? (Score 1) 48

by lourd_baltimore (#48002307) Attached to: NSF Awards $10 Million To Protect America's Processors

The show was probably about the Okavango River which empties into the Okavango Delta in Botswana.

You're right, none of the water makes it to any sea or ocean. Some of it simply evaporates. However, the majority of the water allows for a thriving ecosystem to exist in an otherwise arid region.

Include this into your analogy as you see fit.

Comment: Re:Bogus argument (Score 1) 311

by lourd_baltimore (#44068327) Attached to: Are You Sure This Is the Source Code?

The problem is that GCC will always give you a different binary every time you compile from the same source.

I tried compiling "Hello World" using GCC 4.4.3 and then building it again five minutes later. The executables were binary identical. Is what you said only for non-trivial cases such as "Hello World"?

Comment: Re:Kudos God Win (Score 1) 1061

by lourd_baltimore (#42323839) Attached to: Anonymous Hacks Westboro Baptist Church
Maybe it's a matter of language, but ad-hominem arguments ("any fool") don't work either. You weaken your argument. (Who keeps modding you up?)
Which, I have to admit, I'm not entirely sure that you are debating anything to the heart of the matter, but ... here we are.

I think you're going a little personal on someone's flippant slippery slope comment. No one ever said stop judging, but a real think about statutes need to come into play rather your gut-feeling/Miller Test.
If you want to post in generalities, then I guess, yeah, you admit that hate speech laws will be used to censor. One man's cheeky Mohammad cartoon is another man's hate speech/blasphemy.
Just because people speak in proverbs or or logical fallacies doesn't mean that they don't happen. Please elaborate how, since the ratification of the US Constitution, speech freedoms are greater today.
If you do not believe that once given more control (laws), then one party (government) will not seek more control. Well, I see your logic, but you should bone-up on more history and less philosophy.

Comment: Re:Kudos God Win (Score 1) 1061

by lourd_baltimore (#42312319) Attached to: Anonymous Hacks Westboro Baptist Church

i can tell the difference between homosexuality and necrophilia. i can tell the difference between marijuana and meth. and i can tell the difference between political speech and hate speech

the slippery slope is an idea that only works in a world where nobody can think and identify different topics. therefore, the slippery slope never works as a persuasive argument

Your argument seems to assume that we can all argree on objective definitions of sexuality, drugs, and speech. Differences in drugs can be objectively determined. Sexuality I'll give you as well. Can you honestly say we all agree on what is hate speech? If not, then yes, hate speech laws can, and most likely will be, abused to censor one party. It may not be a slippery slope, but the infringement of rights will occur.
There is a fine, but important distinction you need to state in your case against using the slippery slope.

the slippery slope is an idea that only works in a world where nobody can objectively and uniformly identify different classes.

The slippery slope argument is, by nature, not logical, but if you're going to take the time to dissect a piece of rhetoric, then get it right.

Repel them. Repel them. Induce them to relinquish the spheroid. - Indiana University fans' chant for their perennially bad football team

Working...