From the very first day that humans sent rockets and even satellites into the Earth’s orbit, we have been constantly leaving garbage in space. Now, there are thousands of dead satellites in addition to millions of debris and junk left in space. They are called space junk, or space debris. They are from big objects like dead satellites to smaller things like bits of debris that have fallen off a rocket.
With the ever-increasing amount of space junk around the space, many questions arise. How much are they? Are they imposing any kind of threat? What should be done about them?
How much space debris floats there?
Let’s review some figures. Since the start of the space age in 1957, about 5560 rockets have been launched so far. These rockets have placed roughly 9600 satellites into the Earth’s orbit, 5500 of which are still floating in space. From these, 2300 are still functioning and the rest are dead.
The total mass of all space objects in the Earth’s orbit is more than 8800 tons. There are currently 34,000 debris into space bigger than 10 cm, 900,000 debris between 1 cm and 10 cm, and 128 million debris between 1 mm and 1 cm.
The situation seems terrifying even now, and it is getting worse gradually.
The risks imposed by space debris
Space debris, if not removed, remains in space until it gets back to the atmosphere where it burns. Debris left in a few hundred kilometers can return to the atmosphere after a few years; however, debris or satellites left at higher altitudes of 36,000 kilometers may continue circling the Earth for hundreds to even thousands of years. Unfortunately, most communication and weather satellites orbit in these altitudes.
Fortunately, space debris does not impose a big risk on human exploration deeds. The big problem here is the danger they make for other satellites. As a matter of fact, they are enough to shatter satellites. Satellites have to move away not to collide with junks. Although satellites perform hundreds of collision avoidance maneuvers every year, the collision risk still exists.
Even small flecks of paint, of which there are millions, can destroy different kits and equipment, including the International Space Station. Also, with the passage of time, debris breaks up into smaller pieces, making it even impossible to track it by radar and eliminate it. The damage debris makes to a satellite can be catastrophic.
What worsens the situation is that many companies are constantly adding more and more satellites into space. These satellites are called mega-constellation and are supposed to distribute Internet access worldwide. SpaceX’s Starlink technology along with Amazon’s Kuiper project are two of the biggest programs intended to make worldwide satellite Internet access available.
if successful, mega-constellations projects will add as many as 50,000 satellites into orbit, and they have just begun. That simply means we will need many more collision avoidance maneuvers then.
The Earth’s orbit is so vital for us to investigate our planet, send communications, and many things else. It is of high importance to keep it junk-free to enjoy the benefits it provides.
How to collect space debris
Collecting space debris is going to be absolutely difficult. Scientists are investigating different schemes to remove hazardous debris from the Earth’s orbit. Here is a list of some methods that are under review to make removing debris possible:
· Capture mechanisms: using different kinds of capture mechanisms to grab debris, such as nets, robotic arms, harpoons, and tentacles.
· Electrodynamic tether: using an electrodynamic tether whose current can decrease the speed of debris. Slowing down the space junks makes them gradually fall down and enter the Earth’s atmosphere where they burn up.
· Swinging: to save fuel, this idea proposes swinging debris towards the Earth’s atmosphere, such that they can sail on to the next pieces of debris for removal.
· Solar sail: a huge solar sail can push space debris to lower altitudes.
· Air bursts: in this method, a balloon or high-altitude plain can push satellites into lower orbits by using air bursts within the atmosphere. This way, a generated pulse can push the debris down.
· Electrodynamic network: in this method, a network of nanosatellites is connected with a 3-kilometers-long electrical tape that can produce a voltage as it passes through the Earth’s magnetic field. The electricity it produces knocks debris down.
The promising projects
Most of the methods proposed to clear the space debris have remained in theory mode. In practice, no remarkable project has been launched to remove space junks, except for a couple of promising projects that have been launched recently.
For example, Japan is developing a satellite that uses magnets to catch and destroy the debris. The UK also designed a device that could cast a net around a dummy satellite. Also, the European Space Agency announced a few months ago that the first project to tidy up space is going to launch soon. The project’s name is ClearSpace-1.
Through this project, a four-armed robot will latch onto debris and bring them back to the Earth’s atmosphere, where both the machine and debris burn up. The mission will go through some tests at low orbit, starting from this year. If everything goes smoothly, the mission will target larger objects and we will see an official launch in 2025.
The funding barrier
The big obstacle ahead of these projects is how to fund them. The aforementioned UK device cost $17 million, and the ClearSpace-1 robot has a budget of $111 million. We need to wait longer to see how we will finally get rid of space debris, or maybe before that, SpaceX and Amazon do that for us; only time will tell.