Post by CAPT Issac R. Madden on Nov 9, 2014 12:02:33 GMT 1
I'm not sure how contentious this topic will be among us so I'm dropping it in R&P as a precaution and to save Linders the headache of moving the thread in case it gets a bit crazy.
As many of you know, I'm a huge space nerd (well a huge nerd in general, but I digress) and as such I try to keep up with the latest happenings in space along with learning about experimental stuff that never flew. Some of it makes me ask what the fuck the designers were thinking while others piss me off when I realize where we'd plausibly be now had we stayed the course rather than caving in to someone's pet project and politics.
Let's start with my number one "WTF were they thinking" concept: Project Orion. This concept was a possible means of interplanetary travel with potential speeds of 0.08 to 0.10c or 8-10% of the speed of light using 1940s-1950s era technology with a highly refined and advanced variant potentially enabling speeds up to 0.80c. There was one tiny issue though, the idea behind the Orion-type propulsion system was basically the ship would jettison a small nuclear device (fission initially before progressing to fusion and eventually matter/antimatter) out the back which would detonate and the ship would ride the blast wave to accelerate and decelerate. Yeah... riding a nuclear explosion, not only would the ship have to be insanely durable, but creating the sheer number of devices needed for even the smallest ship (540 devices) would be ungodly expensive and be a huge security nightmare as each pulse device was intended to be no larger than 6 inches in diameter while weighing 300 pounds. Basically we're talking the size of an overgrown soda can and the intent was to use machinery similar to that used in vending machines for mass production/handling of these devices (Coca-Cola corporation was actually consulted on these aspects while the program was still funded). Now each fission-based device would "only" have a yield of 0.15 kilotons or 150 tons TNT equivalent so not particularly powerful by nuke standards, but when we're talking a 6-inch diameter device weighing 300 pounds and the sheer number of devices they intended to produce, you could imagine what kind of a terrorist's wet dream that would be. This program was cancelled in 1963 as part of the Partial Test Ban Treaty and to be honest, I'm very much ok with that outcome.
Moving on, we have the Nuclear Energy for Rocket Vehicle Applications or NERVA program. This concept was what is known as a nuclear thermal rocket (NTR) where the idea is to take a small reactor, run it up to operating temperature, and then liquid hydrogen is run through channels in the reactor where it is heated and jets out of a standard rocket nozzle. While not as powerful as a chemical rocket in terms of pure thrust (which is how much power a rocket engine generates), it's far more efficient with about twice the specific impulse (amount of time measured in seconds that the rocket will run with its fuel load assuming constant operation; think of it as the rocketry version of a car's miles/kilometers per gallon rating). NTRs are also only about half the mass of a chemical rocket enabling a lighter vehicle for the same payload or double the payload for the same weight depending on the craft's configuration. One drawback of this system, though is a NTR just doesn't produce enough thrust for launches from Earth to orbit, limiting it to upper stage use and requiring standard chemical rockets to get it into space. However, once in space, the NTR truly shines as its efficiency enables it to operate for quite some time without needing to be refueled making it ideal for something like a lunar shuttle which can travel from low Earth orbit (LEO) to the moon and back while carrying cargo and crew. Also, the technology exists to do refueling in orbit (we do it routinely with the International Space Station) so such a ship is more than feasible. To make this concept even better, all the testing NASA did with NERVA showed the following:
-The rocket was capable of long run times with the first prototype accumulating a total of 115 minutes of operation including a constant 28 minutes at full power and 28 starts with the same engine
-If such an engine were used for the upper stage of a Saturn V (Apollo moon rocket/Skylab rocket) could place 155 metric tons into LEO (an increase of about 31% over the conventional Saturn V; for reference, Skylab had a mass of 77 mt when it was launched) or about 61 mt to the moon compared to the 47 mt for Apollo
-The engine core was actually quite safe: one part of the program was destructive testing and the engineers found that in order to kill the rocket, they had to not only deliberately and extensively modify the reactor well outside its original parameters for it to to go into overload but they also had to use explosives to simulate a catastrophic failure as the engine itself just plain refused to blow up; when they blew it up, the debris was safe to handle after being allowed to sit for 3 weeks and radiological contamination was minimal
Basically, with 1960s era technology we had a safe and reliable nuclear-based rocket that was ready to fly. Sadly, it was killed by the Nixon administration in favor of the Shuttle. This is incredibly frustrating to me because we could have had a permanent moon base by the 1980s and regular manned missions to Mars by the early 2000s with the trip time to Mars cut from 6 months to 6-8 weeks due to the efficiency of the rocket allowing a greater overall speed over time (more fuel on board for the same weight allows more thrust overall for both acceleration and deceleration) and a more direct trajectory for the flight plan. Sadly, the political environment is such that almost every layperson is terrified of anything nuclear (the fact that the Navy uses nuclear routinely without incident notwithstanding) so support and funding is non-existent today.
Speaking of the Shuttle, that ship is one spacecraft I would flat refuse to fly on. While the design and concept in itself wasn't that bad, it had one critical flaw throughout its time in service: it didn't have a launch escape system (LES). A launch escape system is basically a means of getting a crewed ship away from the launch stack in case of emergencies. This is seen on nearly every crewed vehicle as a small rocket attached to the nose of the ship seen in the picture below.
en.wikipedia.org/wiki/Launch_escape_system#mediaviewer/File:Apollo_Pad_Abort_Test_-2.jpg
Now the Shuttle's design precluded that type of LES, but making the crew cabin a detachable escape capsule was feasible (the B-58 supersonic bomber had such a system), but NASA felt that implementing such a safety feature was too expensive and time-consuming. The only Shuttle that had any kind of true escape mechanism was Columbia which had a pair of modified SR-71 high-altitude ejection systems (which were useless in orbit since orbital velocity in LEO is Mach 25 and space suits just can't withstand the stress of re-entry speeds which are even faster) for the two-man crew used in the first 4 test flights which were subsequently removed after the shuttle was declared operational. Another issue the Shuttle had was trying to do too much with one vehicle which limited its overall capability; basically it had to place 45 mt into LEO for its cargo payload (like a satellite) on top of being man-rated which limited its ability to maneuver to different orbits (had it been purely a crewed vehicle, that 45 mt could have been used for extra propellant/life support/escape systems).
On the opposite side of the human spaceflight spectrum, you have the Russian Soyuz Spacecraft. Soyuz was originally designed to be Russia's answer to Apollo, but the carrier rocket was a total failure (it had a tendency to explode with the force of 7 kilotons due to massive failures in its first stage) so the Russians modified it for LEO and kept updating it as new technology became available. Although the base design is over 50 years old, there has only been two fatal accidents over its entire career: the first capsule failed to deploy its parachute upon re-entry and the eleventh had a bad cabin seal that caused fatal decompression. Now there have been several near-misses, but Soyuz remains the safest, most reliable human-rated spacecraft in service. It's basically what Apollo could have been had it not been killed in favor of the Shuttle.
As many of you know, I'm a huge space nerd (well a huge nerd in general, but I digress) and as such I try to keep up with the latest happenings in space along with learning about experimental stuff that never flew. Some of it makes me ask what the fuck the designers were thinking while others piss me off when I realize where we'd plausibly be now had we stayed the course rather than caving in to someone's pet project and politics.
Let's start with my number one "WTF were they thinking" concept: Project Orion. This concept was a possible means of interplanetary travel with potential speeds of 0.08 to 0.10c or 8-10% of the speed of light using 1940s-1950s era technology with a highly refined and advanced variant potentially enabling speeds up to 0.80c. There was one tiny issue though, the idea behind the Orion-type propulsion system was basically the ship would jettison a small nuclear device (fission initially before progressing to fusion and eventually matter/antimatter) out the back which would detonate and the ship would ride the blast wave to accelerate and decelerate. Yeah... riding a nuclear explosion, not only would the ship have to be insanely durable, but creating the sheer number of devices needed for even the smallest ship (540 devices) would be ungodly expensive and be a huge security nightmare as each pulse device was intended to be no larger than 6 inches in diameter while weighing 300 pounds. Basically we're talking the size of an overgrown soda can and the intent was to use machinery similar to that used in vending machines for mass production/handling of these devices (Coca-Cola corporation was actually consulted on these aspects while the program was still funded). Now each fission-based device would "only" have a yield of 0.15 kilotons or 150 tons TNT equivalent so not particularly powerful by nuke standards, but when we're talking a 6-inch diameter device weighing 300 pounds and the sheer number of devices they intended to produce, you could imagine what kind of a terrorist's wet dream that would be. This program was cancelled in 1963 as part of the Partial Test Ban Treaty and to be honest, I'm very much ok with that outcome.
Moving on, we have the Nuclear Energy for Rocket Vehicle Applications or NERVA program. This concept was what is known as a nuclear thermal rocket (NTR) where the idea is to take a small reactor, run it up to operating temperature, and then liquid hydrogen is run through channels in the reactor where it is heated and jets out of a standard rocket nozzle. While not as powerful as a chemical rocket in terms of pure thrust (which is how much power a rocket engine generates), it's far more efficient with about twice the specific impulse (amount of time measured in seconds that the rocket will run with its fuel load assuming constant operation; think of it as the rocketry version of a car's miles/kilometers per gallon rating). NTRs are also only about half the mass of a chemical rocket enabling a lighter vehicle for the same payload or double the payload for the same weight depending on the craft's configuration. One drawback of this system, though is a NTR just doesn't produce enough thrust for launches from Earth to orbit, limiting it to upper stage use and requiring standard chemical rockets to get it into space. However, once in space, the NTR truly shines as its efficiency enables it to operate for quite some time without needing to be refueled making it ideal for something like a lunar shuttle which can travel from low Earth orbit (LEO) to the moon and back while carrying cargo and crew. Also, the technology exists to do refueling in orbit (we do it routinely with the International Space Station) so such a ship is more than feasible. To make this concept even better, all the testing NASA did with NERVA showed the following:
-The rocket was capable of long run times with the first prototype accumulating a total of 115 minutes of operation including a constant 28 minutes at full power and 28 starts with the same engine
-If such an engine were used for the upper stage of a Saturn V (Apollo moon rocket/Skylab rocket) could place 155 metric tons into LEO (an increase of about 31% over the conventional Saturn V; for reference, Skylab had a mass of 77 mt when it was launched) or about 61 mt to the moon compared to the 47 mt for Apollo
-The engine core was actually quite safe: one part of the program was destructive testing and the engineers found that in order to kill the rocket, they had to not only deliberately and extensively modify the reactor well outside its original parameters for it to to go into overload but they also had to use explosives to simulate a catastrophic failure as the engine itself just plain refused to blow up; when they blew it up, the debris was safe to handle after being allowed to sit for 3 weeks and radiological contamination was minimal
Basically, with 1960s era technology we had a safe and reliable nuclear-based rocket that was ready to fly. Sadly, it was killed by the Nixon administration in favor of the Shuttle. This is incredibly frustrating to me because we could have had a permanent moon base by the 1980s and regular manned missions to Mars by the early 2000s with the trip time to Mars cut from 6 months to 6-8 weeks due to the efficiency of the rocket allowing a greater overall speed over time (more fuel on board for the same weight allows more thrust overall for both acceleration and deceleration) and a more direct trajectory for the flight plan. Sadly, the political environment is such that almost every layperson is terrified of anything nuclear (the fact that the Navy uses nuclear routinely without incident notwithstanding) so support and funding is non-existent today.
Speaking of the Shuttle, that ship is one spacecraft I would flat refuse to fly on. While the design and concept in itself wasn't that bad, it had one critical flaw throughout its time in service: it didn't have a launch escape system (LES). A launch escape system is basically a means of getting a crewed ship away from the launch stack in case of emergencies. This is seen on nearly every crewed vehicle as a small rocket attached to the nose of the ship seen in the picture below.
en.wikipedia.org/wiki/Launch_escape_system#mediaviewer/File:Apollo_Pad_Abort_Test_-2.jpg
Now the Shuttle's design precluded that type of LES, but making the crew cabin a detachable escape capsule was feasible (the B-58 supersonic bomber had such a system), but NASA felt that implementing such a safety feature was too expensive and time-consuming. The only Shuttle that had any kind of true escape mechanism was Columbia which had a pair of modified SR-71 high-altitude ejection systems (which were useless in orbit since orbital velocity in LEO is Mach 25 and space suits just can't withstand the stress of re-entry speeds which are even faster) for the two-man crew used in the first 4 test flights which were subsequently removed after the shuttle was declared operational. Another issue the Shuttle had was trying to do too much with one vehicle which limited its overall capability; basically it had to place 45 mt into LEO for its cargo payload (like a satellite) on top of being man-rated which limited its ability to maneuver to different orbits (had it been purely a crewed vehicle, that 45 mt could have been used for extra propellant/life support/escape systems).
On the opposite side of the human spaceflight spectrum, you have the Russian Soyuz Spacecraft. Soyuz was originally designed to be Russia's answer to Apollo, but the carrier rocket was a total failure (it had a tendency to explode with the force of 7 kilotons due to massive failures in its first stage) so the Russians modified it for LEO and kept updating it as new technology became available. Although the base design is over 50 years old, there has only been two fatal accidents over its entire career: the first capsule failed to deploy its parachute upon re-entry and the eleventh had a bad cabin seal that caused fatal decompression. Now there have been several near-misses, but Soyuz remains the safest, most reliable human-rated spacecraft in service. It's basically what Apollo could have been had it not been killed in favor of the Shuttle.