Instead of using chemical fuels, small “atomic bombs” will be used to propel giant spaceships at a faster speed and carry a load many times larger.
Since mid-2017, billionaire Elon Musk has surprised the world when talking about his ambition to send people to conquer Mars. That ambition is becoming closer to reality when the images of the Falcon Heavy rocket, the rocket is expected to help humans conquer Mars. According to a statement by SpaceX, Falcon Heavy will become the most powerful rocket today.
With a length of up to 70m, a width of 12.2m and a main body diameter of 3.66m, the total mass of Falcon Heavy reaches more than 1,420 tons. This rocket has two stages, with the first stage consisting of 3 tubes with a thrust of more than 23,000 kN, the second stage with a thrust of 934 kN. With such powerful propulsion, Falcon Heavy can carry up to 64 tons of cargo to low Earth orbit, and will drop to 16.6 tons if the destination is Mars.
The low efficiency of chemical rockets forces manufacturers to balance payload and fuel mass, thus limiting the amount of cargo that can be carried for long journeys. In practical terms, chemical rockets typically cost up to 16 tons of fuel to put a tonne payload into orbit, and about 1,000 tons of fuel for every ton of payload to the Moon.
SpaceX’s Falcon Heavy rocket.
But imagine a spaceship 60m high, weighing about 4,000 tons but capable of carrying up to 1,600 tons into orbit with a crew of about a dozen people, enough for a small group of settlers on distant planets. sticky rice. Not only conquering Mars, the ship is also a means for humans to reach Saturn. And like SpaceX’s rockets, the entire spacecraft is reusable.
How can a spacecraft achieve such high efficiency and reach such remote places, the Orion project is the answer to that. By dropping atomic bombs below the stern and detonating them, the whole spacecraft would “ride” on the shock waves generated by the explosion to move forward with tremendous acceleration and The thrust pulse lasts up to 6,000 seconds, 14 times longer than a chemical rocket.
Before Orion, there were many other projects that wanted to harness the tremendous energy from atomic nuclei to power rockets into space. Most of these projects harness the heat generated by nuclear reactors to heat the expansion of jet fuels, such as liquid hydrogen, and generate thrust when ejected through nozzles.
Although operating under stationary test conditions, when tested under the harsh conditions of a space trip, these engines have not shown to be reliable, as they are completely capable. may melt if the jet fuel unit is not operating correctly. The risk of a nuclear reactor that could explode at any moment in the middle of the atmosphere is not pleasant. As a result, these projects were eventually cancelled.
Meanwhile, Orion has a different approach than previous projects on how to exploit this energy source.
Orion’s Birth
In 1957, the Soviet Union shocked the world when it launched the world’s first artificial satellite, and that event prompted the US space program to act faster. That led to the creation of NASA and the reluctance to accept the use of military rockets for civilian programs, to race to the Moon.
It also opens the door to a number of other projects that should have been abandoned. One of them is Orion. Funded by DARPA’s predecessor, ARPA, the Orion project was launched in 1957 under the leadership of atomic weapons designer Theodore Taylor at General Atomic, based in California.
Drawing depicting Orion.
Founded in 1955, General Atomic is part of the US Atomic for Peace program. Aiming at finding peaceful applications of nuclear energy, this project is famous for inventing a nuclear reactor for the purpose of TRIGA research. Between 1957 and 1965, General Atomic recruited 50 people for the Orion project and spent .4 million. To add credibility to Washington, they invited physicist Freeman Dyson as a consultant, and Taylor’s team included many other scientists from the Manhattan project.
Like the nuclear engine, Orion was conceived the day after the first atomic bomb was detonated. Manhattan project team member, Polish-American mathematician Stanislaw Ulam wondered, what if instead of using rockets to carry bombs, bombs were used to carry rockets?
The basic principle behind Orion is very simple and it is similar to the idea proposed by German inventor Hermann Ganswindt in 1880. It was to build a spaceship that would be propelled by throwing a block. dynamite into a steel bell and detonate it.
For the Orion spacecraft, it would be an atomic bomb that would be released from the stern of the ship, and when it reached a pre-programmed distance, the bomb would explode. The bomb will be wrapped with a special material, like polystyrene, to create a plasma shock wave and propel the ship forward. When the shock wave dissipates, another bomb is dropped and the process continues.
Drawing depicting the propulsion module on the Orion ship, including the compartment for the atomic bombs.
By the end of 1958, the team had to consider a long list of math questions for the ship. What size will the ship be? What is the required size of the bomb? How much explosives are needed? With what rate? How much load can it carry? How long will each particular pulse last? How thick does the crew need radiation protection? Will the ship be able to withstand the shock waves? What is the explosion temperature? Acceleration how? And how will the shock wave propagate?
Theoretical calculations
In addition to the theoretical work, the Orion team also had to field test its principle, as well as the technology to exploit it. In 1959, the group received permission from the US Navy to use their Point Loma facility in San Diego for testing with conventional explosives. The prototype was a 3.3-foot-diameter engine model designed to release six RDX explosives in turn. Every time a block reaches the end of the rope, it explodes and another is dropped. The prototype flew for 23 seconds and reached a height of 56m before being recovered by parachute.
From their tests and calculations, the team discovered that the fundamental problem of this spacecraft is the exact opposite of a chemical rocket. With chemical rocket spacecraft, mass governs nearly every other factor: it must be reduced as much as possible. Amplifier shells were made thinner and electronics had to be miniaturized – every strut, every bolt, every screw had to lose every excess microgram.
Different load levels with Orion’s 20m high propulsion module.
Orion is completely different. Mathematical calculations show that, to survive the impact of a 0.03 kiloton bomb, the ship must weigh at least 800 tons. However, creating such a small bomb is extremely difficult. The calculations show the answer, the bigger the ship, the more efficient it will be. In real terms, an Orion ship can weigh thousands or even tens of thousands of tons to be able to operate.
In 1959, a base model for the Orion was born. It will be as tall as a 20-story building, with a diameter of 40 meters, weigh about 4,000 tons and be able to put 1,600 tons into orbit before returning to Earth. According to Dyson, the Orion will be “created to look like a submarine, not an airplane,” with the use of steel and standard shipbuilding techniques. In fact, they expected the ship to be built by a submarine manufacturer, rather than an airline company.
Orion’s Fuel – “Atomic Bombs”
Throwing an atomic bomb off a spacecraft and using its shockwaves to move is risky, but it has a basis. Orion’s previous ideas envisioned a propulsion system that had a giant bell or steel ball to cover the explosion. Compared to a chemical engine, this system can generate millions of times more energy, hundreds of times faster gas speeds, and temperatures that can reach millions of degrees when the shock waves hit the ship. These will entail too many problems and need a different approach.
The bombs for the Orion project were not military weapons either. They are designed with small dimensions (about 15cm wide and weighing about 140kg), containing as little Uranium and Plutonium as possible, with a capacity of about 0.15 kilotons.
The drawing depicts the design of a “bomb” that propels the Orion ship.
Thousands of such bombs were stored in empty compartments in the center of the ship. When accelerating, these bombs will be loaded onto a conveyor with a Gatling machine gun-like mechanism to fire through a hole in the stern of the ship at up to four rounds per minute before detonating at a distance of 20-30. m.
Each bomb works in a similar way to an anti-tank missile warhead, with the detonation block being the nuclear material and the copper cone in the conventional warhead being replaced with other materials such as tungsten, polystyrene or even ice lice. It’s actually the mechanism to convert the explosive energy into propelling the ship forward.
For a standard Orion craft, it would take about 800 “bombs” to drop within six minutes to propel it to an altitude of 483 kilometers in the orbital region. Each explosion would accelerate the ship by 32 km/h and several thousand such bombs would be needed for an interplanetary trip.
King of shock absorbers
Of course, a shock wave of such great power would not reach the unprotected Orion modules. Instead, there will be a giant thrust disk made of steel or other heavy metal with a mass of 500 to 1,000 tons. It will be covered with a plastic layer similar to the insulation of a spacecraft’s shell to protect it from abrasion and absorb maximum energy from the shock wave, and to allow rapid cooling of the plasma before it is released. to the next explosion.
However, there is still another problem. The atomic bomb would cause the whole ship to reach an acceleration of 10,000 G, while the normal safe limit for humans is only about 5 G. This meant they needed a solution to protect the passengers and crew. of the flight. Otherwise, the pressure from the sudden acceleration of the whole ship would crush everyone present on it.
The blueprint of the giant thruster disk at the bottom of the ship.
It was a giant shock absorber – the king of shock absorbers – fitted to Orion. By design, just behind the upper ejector disc is a giant airbag filled with inert gas. Behind it is a series of large pistons lined up in a circle, which act like an aircraft carrier catapult, but in reverse. It uses a system of cylinders, revs, springs and magnetic clutches to absorb and disperse the impact of each shock wave.
By adjusting to the frequency of the shock wave, the acceleration can be reduced to only 4 G, an acceptable level. However, the entire thrust disk and suspension system will become quite complicated, as the researchers also have to account for cases where the bomb does not explode or explode but not at the critical mass level.
Design drawings for Orion’s giant shock absorbers.
Despite the calculations made for the Moon landing, the team seems to think that repeating Apollo’s feat is not worthy of Orion, so they expect a flight to Mars in the near future. 1965. The trip to the Red Planet will take 258 days. The project team even hopes to reach Saturn in 1970. That’s not just about landing on the Moon, instead, they also hope to start colonizing on its surface.
Currently, a mission to Mars is only aimed at putting on a rover or a small group of 3 astronauts, Project Orion plans to send between 20 and 50 explorers, to act as a team. small to serve as outposts for a mission lasting up to 4 years. From Mars, they explore and obtain water to fuel the bomb and direct the ship to Saturn.
Not stopping there, with payloads up to thousands of tons for interplanetary travel, Orion is seen as a way to reach the entire solar system and beyond. With such a vision, a short time later, the drawings for a more advanced, 10,000-ton Orion were ready.
The crew module is not only spacious but also fully equipped.
Difficulties outside of technical factors
The technical issues are almost complete, but testing has only been conducted through computer models and conventional explosives. While the project needed to move quickly to detonation testing with nuclear bombs, the US government was very reluctant to license them.
Not only that, because ARPA belongs to the US Department of Defense, of course Orion’s budget also depends on this agency. Unfortunately, the US Secretary of Defense under the Kennedy Administration, Robert McNamara, did not view Orion as a military asset and refused to raise any funds beyond a feasibility study for the project.
Despite taking into account the complex technical details of the ship, the whole project is still questioned by the risks stemming from its own operating principle: that is the danger from radioactive fallout from the spacecraft. atomic bomb in use.
If an atomic bomb were used to lift Orion from the launch pad, it would create a huge cloud of fallout that would spread through the atmosphere. Therefore, the team decided that it would be lifted up with conventional explosives, and when at high altitude new atomic bombs would be used. At this mid-air height, the bomb would have produced less fallout.
Physicist Dyson estimates that, if a 6,000-ton Orion were to use conventional nuclear weapons, it would produce the same amount of fallout as dropping a 10 Megaton nuclear bomb. This amount of radiation is enough to cause 0.1 to 1 cancer death worldwide. Thus, a single launch for the Mars mission would cause the death of 10 people – an overwhelming number.
Meanwhile, Taylor believes, the special design of the bomb can reduce the level of damage from fallout below the number 10 above, or even eliminate it completely, if it can cause an explosion. fusion explosion is less polluting.
That’s just a calculation for the case where the bomb explodes as intended. Of course, the prospect of a bomb not exploding and falling directly to the Earth, or burning up in the middle of the atmosphere would be unpleasant. Another problem is that if the bomb contains any metals, such as tungsten, they will not only become radioactive, but also ionize space along regions of the Earth’s magnetic field and re-enter the atmosphere. book.
Not only that, at this time, the Kennedy government was also trying to negotiate a Nuclear Test Ban Treaty with the Soviet Union. These negotiations and the radiation issue made lobbying for the project impossible.
In 1963, the Partial Test Ban Treaty was signed between Great Britain, the United States and the Soviet Union to ban nuclear testing on the ground, in the air and in space. American negotiators attempted to get an exception for spaceship testing, but the Soviets refused due to concerns about a flaw in the development of military weapons.
Orion’s Death
Project Orion is now in despair. Without nuclear tests, it would be impossible to develop spacecraft. In the race to space, the government turned in favor of Apollo and Saturn V, removing Orion from the mainstream space program. Meanwhile, the Air Force was stuck with another non-military project, and they could not support the project either.
By the end of 1963, the only agency still interested in Orion was Strategic Air Command, which was intrigued by a fleet of spaceships. Ironically, all the team was able to demonstrate was a model about 2.5m high to simulate what the finished ship would look like. For Washington, this is less convincing than a vague idea.
In 1964, arguing that Orion was not just a civilian project, but also diverting funds for defense projects, the Air Force transferred Orion to NASA. By this time NASA had its own nuclear rocket project and considered Orion only a legacy of the Department of Defense. Furthermore, they are working on building Apollo and are ready to take off.
In 1965, in a last-ditch effort to save Orion, General Atomic asked the US Atomic Energy Commission (AEC) to authorize ground testing. The AEC accepted the proposal, but NASA deemed it pointless as it did not have plans for manned interplanetary flights.
Orion has no supporters, no quests, and no money. On June 30, 1965, the Air Force officially closed the project and the 7-year-long research project was shelved. The public is not even aware of its existence.
While technical obstacles were not Orion’s main challenge, to this day, political and safety issues are still barriers that make the idea of colonizing Mars with spacecraft work. with atomic bombs became impossible. The small atomic bombs of Orion’s design are exactly what terrorists and extremists have been looking for for years.
Not only that, decades of hiatus also caused other problems: artificial satellites surrounding the Earth. Electromagnetic pulses from a bomb can adversely affect these unprotected satellites. There is also the danger of the heavy ions emitted by the bomb when they are trapped in the Van Allen belt that surrounds the Earth.
Even so, Orion didn’t really disappear. In the 1970s, the British Interplanetary Agency exploited Dyson’s ideas and refined it for Project Daedalus, using a fusion engine similar to Dyson’s to be able to build a ship at high speed. maximum 12% of the speed of light. In 1989, NASA also revealed the Longshot project, with the intended launch of the Space Station Freedom space station, using a 300 kW nuclear reactor to power a fusion engine that could propel a probe. unmanned aircraft to a speed of 4.5% the speed of light.