A Rocket Built By Students Reached Space For the First Time (wired.com) 55
In the early morning of April 21, 10 students from the University of Southern California's Rocket Propulsion Lab successfully launched a rocket above the Karman Line, the imaginary boundary that separates earth's atmosphere and space. As Wired reports, this is the first time a collegiate rocket has made it to space. The team may have successfully accomplished this feat last September with their Traveler III rocket, but the team "failed to activate the avionics payload, so none of its flight data got recorded." From the report: Like the Civilian Space Exploration Team, the USC lab focused on solid fuel rockets, which require far less complicated -- and dangerous -- motors than the liquid fuel rockets launched by SpaceX or Blue Origin. Some of the rockets being developed by the leaders of the collegiate space race have two stages, but the USC team opted for a single-stage rocket. If you're trying to get to orbit, which requires reaching speeds of more than 17,000 mph, a two-stage rocket is a must, so as to jettison the dead weight of empty propellant tanks. But for lower altitudes and speeds, a single-stage rocket can do the trick.
In 2013, the USC rocket team attempted its first space shot with the Traveler I, which exploded just seconds after launch. A similar fate befell Traveler II, which was launched the following year. Clearly, it was time to make some changes. Following the failure of the first two Traveler rockets, the USC team began to develop the Fathom rocket and Graveler motor as testbeds for flight systems that would be used on subsequent space shots. The Fathom rocket was effectively a scaled-down version of the Traveler rocket that allowed the USC team to build multiple rockets in quick succession to see how the subsystems worked together. After extensive ground tests, the team's Fathom II rocket set a record when it reached an altitude of 144,000 feet in 2017. Other collegiate rocket teams had reached only about 100,000 feet. The time seemed ripe to attempt another spaceshot.
In 2013, the USC rocket team attempted its first space shot with the Traveler I, which exploded just seconds after launch. A similar fate befell Traveler II, which was launched the following year. Clearly, it was time to make some changes. Following the failure of the first two Traveler rockets, the USC team began to develop the Fathom rocket and Graveler motor as testbeds for flight systems that would be used on subsequent space shots. The Fathom rocket was effectively a scaled-down version of the Traveler rocket that allowed the USC team to build multiple rockets in quick succession to see how the subsystems worked together. After extensive ground tests, the team's Fathom II rocket set a record when it reached an altitude of 144,000 feet in 2017. Other collegiate rocket teams had reached only about 100,000 feet. The time seemed ripe to attempt another spaceshot.
Orbit is not a matter of altitude (Score:3)
If you're trying to get to orbit, which requires reaching speeds of more than 17,000 mph, a two-stage rocket is a must, so as to jettison the dead weight of empty propellant tanks. But for lower altitudes and speeds, a single-stage rocket can do the trick.
What matters is speed. Horizontal speed to be exact. The only reason rockets go up first is that contact with solid rocks (aka "mountains") is detrimental to lengthy flights and air resistance at sea level is not really comfy anymore at 27k km/h.
Also, the higher you are, the slower you need to go to stay in orbit. But that's of a lesser concern.
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You can in theory launch a rocket and fly it at sea level... as long as you're over the sea, that is. Unfortunately there is no orbit possible on this planet that never crosses land.
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Probably 1 foot higher than the highest point on earth to be safe.
Re:Orbit is not a matter of altitude (Score:5, Informative)
There is actually a launch angle that given the rockets acceleration profile allows it to always accelerate in the direction of flight all the way to orbit, resulting in the most efficient trajectory on an airless planet. For a low acceleration rocket its near vertical, closer to horizontal for high acceleration. If there is air, the optimal path starts out more vertical to trade off trajectory efficiency against air drag.
If you wanted to launch horizontally you would need infinite acceleration or you would fall to the ground before you reached orbital velocity. On an airless planet a space gun would probably fire near horizontal, but air makes that impractical (on top of a space gun being impractical anyway).
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It should be noted, for the record, that Ceres has an escape speed (~520 m/s) rather less than the muzzle velocity of an AK-47 (715 m/s), much less that of a .30-06 (850 m/s)...
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True - I was thinking of an earth based space gun. On low escape velocity worlds its a reasonable technology.
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It should be noted, for the record, that Ceres has an escape speed (~520 m/s) rather less than the muzzle velocity of an AK-47 (715 m/s), much less that of a .30-06 (850 m/s)...
Would an AK-47 fire on a airless planet?
Re:Orbit is not a matter of altitude (Score:4, Informative)
Would an AK-47 fire on a airless planet?
Yes. The thing about explosives is they pack their own oxidizer on the molecule, so they would work in a vacuum for the same reason rocket engines work in a vacuum. If you're providing the reagent and the oxidizer then it works. In fact it would work better since there would be no air resistance in the barrel to oppose the accelerating bullet.
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Short answer: yes.
https://www.livescience.com/18... [livescience.com]
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Would an AK-47 fire on a airless planet?
For a while. As everyone has already pointed out, explosives bring their own oxygen. However, modern guns rely a lot on air cooling, so it would overheat fairly quickly (however, the spent brass carries a lot of heat off with it, which is why caseless ammo never really took off).
There are a few "space guns" designed specifically for use by astro/cosmonauts, but they're just lightweight. At least in the early days of the Russian space program, the cosmonauts always had a gun in the capsule, to defend agai
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a space gun would probably fire near horizontal
In theory. In practice usually any sort of payload, engines, fuel and avionics don't do so well after being exposed to an instantaneous acceleration of 1000g's or so... space "gun" is a no-no. Rail launcher on the other hand...
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You can build all sorts of useful avionics and payload in a gun-fired device provided it's made of robust-enough solid-state electronics. You can even include a simple engine and fuel provided that the moving parts have a safe-stow configuration that keeps them held firmly in place during the initial kick.
This is how guided, rocket-assisted artillery shells work. If all the parts are held tightly in place, the acceleration is spread over the time the projectile is in the length of the barrel.
Obviously this
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it's also easier to dump in the ocean if it travels horizontally
that's actually a legit concern. Most US-launched rockets will turn early, earlier than the ideal "gravity turn", to get over water ASAP in case of rapid unscheduled disassembly. There was one early NASA test flight (unmanned, fortunately), that blew up just off the pad, and while the site personnel were safe in the bunker, everyone's car was destroyed in the parking lot. Needless to say, they try to minimize the risk of that sort of thing.
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However maintaining a speed of more than17,000 mph at low altitude would be nearly impossible. it would burn up from the friction even if it had enough power to keep going at that speed.
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Nah, you’re overthinking it. Somebody forgot to switch the logger on.
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Yes, one would think the person responsible will never hear the end of it from their colleagues.
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what do you think longitude and latitude are? did you think there are actually black lines on the planet ??
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Actually, I was surprised to discover that there is a physical line dividing the US and Canada [atlasobscura.com]. Many years ago I was hiking across the border on the Pacific Crest Trail, and saw there was a massive swath cut straight through the forest right at the monument that marked the border. Later I looked it up, and found it's known as the "Slash". Was very impressive.
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There is some reasoning behind the altitude where space begins. The Kármán line is the altitude where an airplane's lift equals orbital velocity.
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It's weird when talking about science that we use an "imaginary" line, and not some scientifically measured line to determining where space really begins?
More fun, there are two such lines. The US used 50 miles, other used 100 km. Both were just total guesses, from the very early days of rocketry, as to where the atmosphere was thin enough that a satellite could stay up with minimal station keeping.
There's an effort now underway to define the line scientifically based on statistics of the great many satellites in LEO. The answer turns out to be very close to 50 miles. Give it a few more years, and we may have a new standard for "where space begins" tha
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But ... (Score:3)
I don't want them doing manned flights (Score:1)
They'll forget to turn on the oxygen, or even the lights
Old Hat (Score:3)
Call me when we have a propellantless means of flight. Rockets and propellants are so 20th century.
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lolz, so first 13.85 billiion years of the Universe you mean. No flight without propulsion, no propulsion without propellants. True for comets near stars, birds, bugs and human spacecraft.
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Call me when we have a propellantless means of flight. Rockets and propellants are so 20th century.
[Dr Evil voice] We could use some sort of giant "laser" [/Dr Evil voice]
Right now it's the most credible approach for interstellar travel - the big laser stays here, the ship just uses a solar sail. No new technology needed there, just a lot of patience and a really big laser.
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Laser Ablation Propulsion [researchgate.net].
Sponsor (Score:1)
Pfft (Score:2)
Weak.
Give me a cardboard tube, some balsa wood, a few sick rad decals, copious amounts of model glue, a bright plastic nose cone with a couple of streamers, and a few Estees Q engines (with igniters and plugs please, I won't use my personal extras for your contract) and I'll get some shit to space.
Congratulations (Score:2)
It's not anything like orbit, but they've equaled the best speeds/altitudes the world's richest man has managed to accomplish in 19 years of funding Blue Origin. Also higher than Richard Branson can make it. Not bad for a 13 foot rocket built by college kids.