Chapter 2: The establishment of the laser broom In 2040, all the studies about “Meteor” are finished. Governments also finished constructing the setup robotics and the rocket to send the robotics to ISS. On January 13th, 2041, the first rocket for the mission successfully launched. The rocket carried a payload of 1000 kg of robotics for laser broom setup. The final stage of rocket reached to an altitude of 400 km and it successfully docked with ISS. The docking process involves complicated orbital rendezvous so that the rocket stage and the space station arrive at the same orbit and approach to a very close distance.
The docking used V-bar (velocity vector) approach. The rocket stage that carries the robotics moves in the same direction to ISS in parallel in the height of 400 km. To chase ISS, the rocket stage fires small thrusters to increase its velocity to 30,000 km per hour [14]. Additionally, other thrusters are fired in the radial direction, so the rocket stage would not be driven to a higher orbit [15]. If a rocket stage were in a higher orbit, it would move slower than its target. After the docking, the final stage of the rocket opened up its gate and automatically extended a conveyor belt inside ISS.
The conveyor belt transferred the robotics to ISS and started to setting up the infrastructure of the laser broom. The total mass of robotics needed to setup the laser broom infrastructure is as heavy as 5000 kg, heavier than the mass of voyager 1 [16]. Therefore, after the first successfully mission, other five similar rockets were launched to bring all robotics in ISS. The goal of the first three rocket launches is to set up the power system of the laser broom. The power needed by the laser system is 100 kilowatts. Thus, to generate the power, the robotics helped construct eight additional solar array wings.
Each of the wings can fully extend to 35 meters in length and 12 meters in height. Moreover, additional circuits were added to the electrical system so that the laser broom can utilize power generated by the solar panels. The second step of the laser broom set up is to construct 91 fiber lasers. The active gain medium of a fiber laser is an optical fiber. The active gain medium is usually made of rare earth elements, such as erbium, ytterbium and neodymium. Unlike other types of lasers, fiber lasers are constructed monolithically by fusion splicing different types of fiber to replace conventional dielectric mirrors.
The diffraction-limited beam powers of fiber lasers rapidly increased recently from 100 W to 20 kW [20]. In 2014 a combined beam fiber laser demonstrated power of 30 kW [19]. After constructing all fiber lasers, the third step is to combine all the lasers into a Coherent Amplification Network laser (CAN). CAN is developed by the European Organization for Nuclear Research (CERN). According to CERN researchers, a typical CAN laser may use 1000 fibers, each carrying a small amount of laser energy [21]. The lasers coherently combined to generate high peak-power pulses at a high repetition rate.
They often produce pulses with a rate of around 1 Hz [22]. To achieve such a massive network, the combination architectures are based on implementing a spherical array of amplifying fibers, thus removing the need for transport fibers. The CAN laser would focus a single powerful beam on a piece of debris. The laser would vaporize the surface of the target, causing a plume of plasma to push the object away from the station and toward the atmosphere. The full-scale version of the system would use an ultraviolet CAN laser capable of firing 10,000 pulses per second.
That would give it a range of about 100 kilometers, which should be more than enough distance to clear space debris around the station. Additionally, the final step also sets up the control system of the laser and an observatory device to monitor space debris around ISS. Finally, the infrastructure of the laser broom is successfully constructed in 2050 and governments are about to send astronauts Ling, Thomas, Aleksei and Yuki into ISS. At 16:00 pm, October 24th, 2052, a newest Falcon Dragon II rocket carried the four astronauts ware about to launch to low earth orbit.
The launch caught attentions of people around the globe. The success of the mission would be a new era for human space explorations. It would be the first time that humans managed to clean space debris. The white rocket silently lay on the launching platform and ground staff checked the status of the rocket for the last time. Thomas closed his eyes and he could not wait for the exciting moment of launch. Ling nervously took a deep breath. The conductor in Kennedy Space Center gazed at the time shown on his computer screen.
He carefully listened to every single word reported by operators and decisively gave out commands: “10 minutes countdown”… “5 minutes countdown”… “One minute countdown”… “5…4…3…2…1…0…” The young operator on the launching platform calmly pushed the launching button and the rocket on the field blasted off with the throaty roar of the engines. “We have lifted off the Falcon dragon II manned rocket for the first world’s space debris removal mission. ” The crowd marveled at the propellant fire and passionately burst into cheers.
The conductors in control center carefully examined the monitor screens and checked the trajectory of the rocket. After ignition, a hold-before-release system ensures that all engines are verified for full-thrust performance before the rocket is released for flight. Then, with thrust greater than five 747s at its full power, the Merlin engines on the first stage of the rocket launched the rocket to space. The first stage of the rocket has nine Merlin engines and aluminum-lithium alloy tanks containing liquid oxygen and rocket-grade kerosene propellant.
The rocket rapidly flied up and the first rocket stage separated when it entered Earth’s magnetosphere. The magnetosphere is the region of space surrounding the Earth in which charged particles are controlled by magnetic field [23]. Earth’s magnetic field is significantly distorted by the solar wind and solar magnetic field to a distance of approximately 65,000 kilometers [23]. The Earth’s bow shock, within which the solar winds slow, is located 90,000 kilometers from Earth [24]. The Earth’s magnetopause, within which solar winds balance Earth’s magnetic fields, is located several hundred kilometers from Earth [14].
The second stage of Falcon Dragon II ignites a few seconds after the separation. The second stage is powered by two Merlin engines and is in charge of delivering the cargo to Low Earth Orbit. The second stage is also made of aluminum-lithium alloy. The engines of the second stage restarted three times to gradually adjusted its orbits and finally entered the same orbit of ISS. Then, the rocket performed R-bar approach of rendezvous. The R-bar approach consists of the rocket moving below the target ISS along its radial vector [25].
When below the target, the rocket fires radial thrusters to close in on ISS. When the rocket is 4 kilometers higher than ISS, it has a slower orbital velocity than that of the local circular velocity: 27600 km per hour [26]. Small rocket pulses are needed to keep the rocket along the radial vector of its target. While performing the rendezvous, ground operators accurately measured and recorded the location, the speed and the altitude of the rocket at every moment. A huge amount of monitor data is collected by the control center.
The control center incessantly studied different parameters of the data and reported them to operators: “All working properly. ” The operators accurately control the movement of the rocket rendezvous. The rocket finally docked with ISS and the crew entered into the working area of the ISS laser broom. As they entered, the space debris observatory on ISS is controlled to turn on. The observatory sent its first picture to the ground control center. In the picture, a beautiful blue globe is masked with a huge collection of dark spots.
The blue globe is the Earth and the dark spots are space debris on lower orbits. Several beams of greenish and pinkish lights are hidden behind the dark spots in the North pole and they can be barely seen. These lights are Earth’s aurora. Auroras are formed when the magnetosphere is sufficiently disturbed by the solar wind so that the trajectories of charged particles precipitate into Earth’s atmosphere, above 80 km [27]. The energetic charged particles excite N and O atoms in higher energy states [27]. When oxygen and nitrogen atoms return to their ground states that are higher than -13. ev [28], lights with varying colors are emitted.
Although the sun is not active through the year, particles of solar flares can still occasionally penetrate Earth’s magnetic shield and collide with molecules in Earth’s atmosphere. A solar flare is defined to be a sudden variation of brightness in sun. A solar flare occurs when the magnetic energy built up in the solar atmosphere is released. The temperature of solar flares range from 200,000 K to several millions K [29]. The energy released during a flare is typically on the order of 1027 ergs per second [29].
Large flares can emit up to 1032 ergs of energy, which is ten million times greater than the energy released from a volcanic explosion [29]. Solar flares mainly produce X rays and radio waves [30]. However, small amounts of gamma rays can also be produced from nuclear reactions triggered in the chromosphere by high energy protons and ions [30]. After receiving the picture, the ground control center announced the success of the first step of Meteorite mission to media: “We have successfully constructed a space debris removal laser broom in ISS and sent our first crews to maintain the system.
We have confidence that we can begin removing space debris in a few weeks. ” All the people watching the live of the mission excitedly applauded. “We finally made here, crews! ” said by Ivanov, the pilot of the space mission, “In two weeks, we will perform several out space activities to test equipment and ensure the functionality of the laser broom. After all the tests and preparations, we will start our first space debris removal mission. ”
