Posted on 07/28/2007 2:35:56 PM PDT by anymouse
Rocketeers By Michael Belfiore Smithsonian, 305 pages, $26.95
American space exploration had a rough time of it on Thursday. NASA's already bruised reputation took a one-two punch with revelations that on at least two occasions astronauts were allowed to fly even though they were intoxicated and that a computer due to be delivered to the International Space Station in August had been sabotaged. The news might have bolstered the case for the increasingly robust efforts at privately funded space ventures, except Thursday also brought news of a deadly explosion at a Mojave Desert airport where a propellant system for a space-tourism vehicle was being tested. Three workers were killed and three others injured in the accident at a testing facility owned by Scaled Composites, the company that built SpaceShipOne, the first privately owned, manned craft to reach space.
But despite these setbacks -- as with past misfortune in the space industry -- the push to venture far from Earth will no doubt continue. The only question is just when commercial enterprises will begin to pose a serious challenge to government-funded space exploration. The answer: soon. That, at least, is the message of "Rocketeers," Michael Belfiore's enlightening survey of the entrepreneurs bent on conquering space.
(Excerpt) Read more at online.wsj.com ...
space ping
The nitrous oxide isn't used as a propellant on Rutan's rockets. It is used as an oxidizer.
Don't expect a reporter to get it right though. That's asking just too much these days...
Thanks for posting, Anymouse. I love this stuff. Are you aware of any FR ping lists covering stories like this?
KevinDavis has a space ping list.
aeronaut also has an aviation ping list.
The ET's never get up to orbital altitude; it would add about half again as much propellant from liftoff to carry it up there.
Go watch this, old cuz, as it goes right along with our conversation this afternoon...
Also visit this http://www.spaceislandgroup.com/home.html
You are wrong there, old sport...
Don't know who gave you that info, but it is not correct. Both it and the shuttle have the inertia to reach orbit when they separate, but by casting off the ET, it falls into a trajectory where it quickly reenters the atmosphere and burns up while the shuttle says on course reaching orbit..
If you doubt this, tell me how does the shuttle reach orbit after separation if it needs more fuel when the fuel tank (The ET) has been cast away?
An oxidizer is a propellant. Propellants are oxidizer plus fuel.
No. Propellants are distinct from their oxidizers.
The ET takes the shuttle about 95% of the way up, but the climb to final orbit is done by the Orbital Maneuvering System. The ET weighs about 70,000 pounds 'dry', so adding the extra fuel to push the load all the way up adds exponentially back down to the pad. The OMS has at least one major burn to attain the height, then as needed to establish circularity.
I don't think there's much over a couple hundred pounds of LOX and H left at separation, they plan the quantity pretty close and don't need extra to fly up.
Wish I still had my contact list from the Columbia tragedy, there were several real rocket scientists in the group. Crashed hard drives and CRS don't mix well. :^)
Not a moment too soon, if you ask me.
“The nitrous oxide isn’t used as a propellant on Rutan’s rockets. It is used as an oxidizer.”
If nitrous oxide as an oxidizer is not a part of the pro;ellant system, try “propelling” a rocket using an oxidizable fuel without it.
as for the hazards of high pressure, consider the new air powered vehicles coming out of India - these use piston engines powered by high pressure air as “fuel”. The air tank on these vehicles to power these engines is pressurized to 5,000 psi. Are these accident proof tanks?
Yes.
Propellants are distinct from their oxidizers.
No, propellants are what are emitted from the rocket to propel it. In the case of a chemical rocket, it is the fuel and the oxidizer (or rather, the combustion byproducts of the reaction of them). In the case of a thermal rocket, it's whatever you put in the propellant tank. Having three decades of experience in the space industry, this is the first time I've ever heard your idiosyncratic (and incorrect) definition.
From http://www.permanent.com/ext-tank.htm
“After the Boosters are detached early in the flight, the Main External Tank fuels the Shuttle Orbiter tail engines at full thrust to gain the high speed required for orbit. When more than 97% of orbital speed is attained, the External Tank is detached from the Shuttle Orbiter and directed to cross Earth’s atmosphere to burn up (Skylab-like) with remnants falling into a remote section of the Indian Ocean. The Main External Tank cannot be returned to Earth for reuse on later launches because it cannot be returned without burning up in Earth’s atmosphere, unlike the Boosters which detach themselves early before high speeds are attained. Currently, the Main External Tank is just thrown away.
“This wasteful procedure will eventually change. The questions are “when?” and “by who?” NASA has offered to deliver its tank to orbit for free to any entity capable of handling it properly.Notably, the External Tank, when separated from the Shuttle, still has some hydrogen and oxygen in it. This leftover fuel is about 1000 kilograms (roughly 2000 pounds) or 1 ton of hydrogen, and about 6,000 kilograms (13,000 pounds) or 6 tons of oxygen, which is 1% of its liftoff fuel. It also has 500 kilograms (245 pounds) of nitrogen (a refrigerant).
“The hydrogen and oxygen are useful combined as water (7,000 kilograms, or 15,000 pounds per tank). Humans and plants need water, nitrogen, oxygen, and hydrogen. (Oxygen is abundant in lunar soil — 44% of average lunar soil. But hydrogen and nitrogen are difficult to obtain in large quantities, except from asteroids or permanently shadowed lunar polar crater “hydrogen cold traps”.)
“Notably, if the tank is saved, the Space Shuttle can lift MORE payload up from Earth, or it can go up to a higher orbit. Why? Saving the tank would eliminate a maneuvering operation required to send the tank to burn up safely in a small target area at a remote spot in the Indian Ocean. This requires use of fuel on board the Shuttle, which is a compact but relatively heavy fuel (hydrazine), which is also used to propel the Shuttle to its final orbital velocity. Saving the tank would also allow more of the tank’s leftover fuel to be used (by a slow burn at lower tank pressure). An engineering study by the tank’s manufacturer, Martin Marietta, shows that the Shuttle can take an extra ton of cargo to orbit if the tank is saved.”
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