Nov 16 2021

Russia Shoots Down Satellite

Published by under Astronomy
Comments: 0

In the movie Gravity (one of my favorite movies, highly recommended), the Russians shoot down one of their own satellites in order to test their anti-satellite system. The debris from this satellite crashes into other satellites causing a cascade of debris, which travels around the Earth eventually crashing into the ISS and a space shuttle in low Earth orbit. I have to point out that the orbital mechanics in the movie are terrible. One big problem is that objects in the same orbit are going the same velocity, by definition. So the debris would not have been flying by so fast. But putting all that aside, the core concept that space debris is a huge problem, and blowing up satellites in orbit is a horrifically bad idea, is valid.

Which is why it is head scratching that 8 years after Gravity came out Russia would blow up one of its own satellites in orbit in order to test its anti-satellite system. Didn’t anyone in Russia see this movie? More seriously, they should know that this is a terrible idea, contributing significantly to the problem of space debris. The US and other space-faring nations are not happy. In a state department release they said:

“The test has so far generated over 1,500 pieces of trackable orbital debris and hundreds of thousands of pieces of smaller orbital debris that now threaten the interests of all nations.”

The astronauts aboard the ISS had to shelter in capsules for safety as a result of the debris. Our goal is to reduce space debris, not significantly increase it. Russia is not the first country to do this. In 2007 China destroyed one of its defunct weather satellites, producing more than 2,000 pieces of trackable debris. After nearly 65 years of putting satellites into orbit, there are now over a million pieces of debris between 1 and 10 cm orbiting the Earth. NASA is tracking 27,000 pieces of larger debris. While space may seem big, low Earth orbit is finite and valuable real estate. Having more than a million pieces of debris flying around is a significant risk. They can damage satellites and threaten crewed missions, such as the ISS. In fact the ISS frequently has to adjust its orbit in order to avoid tracked debris.

The situation is not sustainable. We are putting satellites into orbit at an accelerating pace, and unless space debris is actively managed low Earth orbit will become increasingly hazardous, increasing the cost of operating satellites and threatening space stations and crewed missions. Blowing up satellites in orbit is nothing short of madness, and clearly should be banned by international treaty.

The worst-case-scenario is the so-called Kessler syndrome, named after NASA scientist Donald Kessler who in 1978 proposed that if the density of satellites in orbit gets beyond a certain point, that one collision in orbit can lead to debris that causes another collision. This can result in a cascade of collision making low Earth orbit essentially unusable. He also published a 2009 analysis concluding that the density of object in orbit was already unstable, meaning that debris was being added faster than atmospheric drag and deorbiting was removing it.

There are efforts underway to reduce space debris, including avoiding adding to the debris and removing what’s already there. New satellites are encouraged to have built in mechanisms to deorbit once their functional lifespan ends. Right now the UN Office for Outer Space Affairs publishes guidelines for minimizing space debris, but I don’t think these have any legal force. Here is the list of guidelines:

Guideline 1: Limit debris released during normal operations

Guideline 2: Minimize the potential for break-ups during operational phases

Guideline 3: Limit the probability of accidental collision in orbit

Guideline 4: Avoid intentional destruction and other harmful activities

Guideline 5: Minimize potential for post-mission break-ups resulting from stored energy

Guideline 6: Limit the long-term presence of spacecraft and launch vehicle orbital stages in the
low-Earth orbit (LEO) region after the end of their mission

Guideline 7: Limit the long-term interference of spacecraft and launch vehicle orbital stages
with the geosynchronous Earth orbit (GEO) region after the end of their mission

Number 4 is of particular interest – avoid intentional destruction. That seems pretty obvious. (And I note that there is a version of this document available in Russian.)

Right now there are lots of proposals for how to remove space debris, none of them home runs. Methods are slow, expensive, and difficult. These include sending up large nets to gather up debris and deorbit it. Another proposal uses lasers to target specific pieces of debris, slow their velocity and drop them out of orbit. One major challenge gets back to orbital mechanics. In order to get to the debris you have to adjust your orbit to match the debris, burning a lot of fuel. That’s why a ground-based solution may be best (like the lasers), but this is not a proven technology. Also, the smaller the debris the harder they are to target and remove. Getting rid of intact defunct satellites will likely be easiest, and will be highly useful (if for no other reason that China and Russia will have no targets to blow up). Getting rid of the small but still large enough to be dangerous debris will be much harder. Imagine a steel bolt flying around and crashing into a satellite, or punching a hole in the ISS. Efforts to clean up debris also can’t interfere with operational satellites, which are becoming more dense. The Starlink project alone plans to put 20,000 satellites into orbit.

I just wish there were one area where humans could be smart and strategic, but the probability of this diminishes exponentially the more people or institutions are involved. There always seems to be someone doing the equivalent of intentionally blowing up satellites.

No responses yet