Monster rocket repeats historical mission
50 years ago, the most powerful rocket ever, Saturn V, sent the first humans to the Moon. In 2020, NASA will repeat the legendary Apollo 8 mission with an unmanned rocket, when the even bigger Space Launch System is launched for the first time.
up through the atmoshere, where it is subjected to immense forces due to air drag, affecting its exterior. In connection with the launch, engineers’ major cause of worry is the max Q point. Max Q is the time of the flight up through the atmosphere, when air drag is at its maximum. If a rocket survives max Q, it will probably resist anything in space.
Space dreams come true
The air drag in the atmosphere and the sensitive weight balance mean that the load must be very consistent with the forces of the rocket. So, several different weight categories of booster rockets exist. The highest one, superheavies, can lift more than 50,000 kg into an orbit around Earth. Only this type of rocket can be used, when the great dreams of the space agencies are to come true in the 2020s by manned missions returning to the Moon and going all the way to Mars.
So, NASA is working on the last details of the Space Launch System (SLS), whose final version will be the largest rocket ever with a lifting capacity of 130,000 kg. But NASA is by no means the only player. The Russian Roscosmos space agency is cooperating with the Energia company to develop a rocket. The project, which is known as the Super Heavy Rocket, will be introduced in 2028. And in China, the CNSA space agency is testing the engines of the huge Long March 9 rocket, which, with a potential lifting capacity of 140,000 kg, will even outcompete the SLS, if it is completed.
It is no longer only the major national space agencies that develop huge rockets. The private space company Blue Origin has announced its next major project by the name of New Glenn. With a lifting capacity of 45,000 kg, the rocket is not very large, but unlike other rockets, New Glenn can be reused about 100 times. The SpaceX company, which now commands the most powerful rocket, Falcon Heavy, is busy developing an even larger craft, the Big Falcon Rocket (BFR), that will be a combination of a booster rocket and a spacecraft along the lines of the pensioned off space shuttle.
Engines are improved
The major difference between the new huge rockets and their predecessor, Saturn V, is the quantity of computer power. The digital revolution has had a major impact on what is possible in connection with modern aerospace activities, particularly when it comes to engine control. When the five powerful F-1 engines of the Saturn V rocket were activated, they more or less continued at the same
force, until the tanks were empty. Falcon Heavy’s 27 engines can vary their intensity via digital control. As soon as the rocket has lifted off from the ground, the main rocket's nine innermost engines are turned down to save fuel, until the craft reaches an altitude, where lower atmospheric pressure means that the energy of the fuel is better utilized.
3D printing makes rockets sturdy
Improved fuel and more powerful engines that are able to send rockets on ever longer missions require construction methods that produce durable rockets.
During launch, NASA’s SLS rocket will be subjected to a heavy impact, when accelerated from 0 to almost 30,000 km/h in only eight minutes. At the same time, the temperatures in the interior of the rocket’s engines will reach some 5,000 degrees, whereas the exterior hull must be able to resist space temperatures of hundreds of degrees below zero. In recent years, a new welding method and 3D printing of engine parts have made things easier.
Ordinary welding between two plates constitutes structural weaknesses of a rocket hull. It makes the surface uneven and so more subjected to the forces of air drag, making it difficult to guarantee the metal’s subsequent strength. But with a new method known as friction stir welding, engineers can obtain wider welding. The welding method is carried out with a fast- rotating cylinder, which moves along the joint, forcing itself against the plates. The friction makes the plates melt, and the circular motion ensures an even distribution of the molten mass. In this way, you get a wide, transitional link between the two plates, which almost become one, as the welding hardens.
In other cases, engineers have managed to eliminate the need to weld by means of 3D printing. 3D printers have the advantage that that they can produce one-piece parts of the rocket with very high structural strength. In December 2017, NASA tested an engine with a 3D printed pogo accumulator, i.e. a sphereshaped, hollow device that absorbs the impact occurring, when fuel flows through the engine under high pressure. The accumulator reduces the pogo effect, which is a hazardous phenomenon, that occurs when the vibrations become self-perpetuating. At worst, the pogo effect could tear the entire rocket apart. The 3D printed engine part functioned wery well, and NASA aims to take a closer look at which other parts can be made using a 3D printer.
Recycling causes rocket mania
Falcon Heavy’s historical test launch proved that rocket engineers have come much further since the heyday of Saturn V. It was clear, when the rocket’s first three stages landed synchronically and vertically on the ground after having launched the load into space; a feat that seemed impossible just a few years ago. Rocket recycling finally allows private companies to offer tourist missions into space that people can afford. The Blue Origin company is fine-tuning a rocket that can launch a small capsule with six passengers into space, and the first tickets will be put up for sale already next year.
In 2014, the Orion capsule was tested for the first time in preparation for the mission around the Moon in 2020. 1 NEWTON IS THE FORCE REQUIRED TO ACCELERATE 1 KG TO 1 M/S IN 1 SECOND.
1968 S AT U R N V
The legendary Earthrise photo was taken by Apollo 8 astronaut Bill Anders on 24 December 1968.