What’s the Deal With Space Junk?

by Modis on May 25, 2017

Space junk orbiting earthSpace, the final frontier.

Growing up many people dreamed about space travel and the opportunity to “go where no man has gone before.” Since the 1957 launch of Sputnik, we’ve launched more than 4,500 spacecraft. Almost 2,200 remain in orbit and of these only 450 are still functional. The rest? Scientists refer to them as orbital debris, otherwise known as “space junk.”

This junk is a major problem. Not only is it filling up Earth’s orbit, but it travels at speeds up to 5 miles per second or 18,000 mph. That’s almost 7 times faster than a bullet! This poses a danger to all space missions. In fact, NASA’s chief scientist for orbital debris says non-trackable space junk is the greatest risk to space missions.

And if we don’t do something about it, space junk could ruin space travel for the future.

What exactly is space junk?

Right now there is a mind-boggling amount of debris floating in space. Some of these particles are natural (meteoroids) and the rest is man-made. Usually, meteoroids orbit the Sun and most artificial debris orbits the Earth. The man-made debris no longer serving a useful function and clogging up our orbit is what we refer to as space junk.

Some examples of space junk are:

  • Fragmentation debris
  • Nuts and tools lost during spacewalks
  • Mission-related debris
  • Abandoned launch vehicle stages
  • Non-functional spacecraft
  • Spent rocket bodies (these can be the size of school buses)
  • Products of spacecraft surface deterioration
  • Aluminum oxide particles from rocket exhaust
  • Paint chips
  • Carriers for multiple payloads
  • Solid rocket motor effluents

There are 3 types of orbital debris that cause concern.

1. Larger than 10 cm: There are an estimated 29,000 of these objects in Earth’s orbit.

2. Between 1-10 cm: There are an estimated 670,000 of these objects in Earth’s orbit.

3. Smaller than 1 cm: More than 170 million of these objects are orbiting Earth.

What’s the big deal?

In 1978, NASA scientist and astrophysicist Donald Kessler developed what we now call the Kessler syndrome. His theory predicted that the density of objects in low earth orbit (LEO) would become high enough that collisions between objects could cause a domino effect where each collision generates more space junk increasing the odds of further collisions.

In 1996, debris from from an Ariane rocket crashed into a French military reconnaissance satellite. This was the first verified case of a space collision between two man-made objects.

In 2007, two satellites, Iridium 33 and Kosmos-2251, collided over Siberia at a speed of 26,170 mph.

We’re witnessing what Kessler predicted almost 40 years ago. Yet, with so much space junk, there have been surprisingly few disastrous crashes.

There are already 521, 000 pieces of trackable orbital debris circling Earth. Any one of these objects poses a threat to an operational spacecraft. If a 10 cm object collided with a typical satellite, it would destroy the satellite. A 1 cm object can penetrate the shields on the International Space Station or disable a spacecraft. Even a 1 mm object can destroy a spacecraft’s sub-systems.

What’s next?

Orbital debris stays in orbit until atmospheric drag and other forces eventually cause their orbits to decay into the atmosphere. Since atmospheric drag decreases as altitude increases, debris in orbit above 600 km can stay there for thousands, even millions of years.

The problem will get exponentially worse because of collisional growth. There will be more fragments generated by collisions than atmospheric drag will remove.

According to Wired, the amount of space junk will double every few years. Companies like Samsung, Boeing, SpaceX, and One Web plan to bring Internet access to every corner of the world using satellites. These “mega-constellations” of satellites will place more than ten thousand satellites in orbit.

What are we doing about it?

There are huge financial and logistical challenges involved in solving this problem. For example, there are many nations and private companies involved. Not everyone agrees on how to address space junk.

The main issue is money. Removing space debris isn’t an economically viable option in the foreseeable future. There have been international efforts to slow creation of more debris.

Spacecraft designers try to protect spacecraft from debris as best they can. They’re also designing spacecraft and launch vehicles for end of life passivation. Other planned tactics for fighting space junk include:

  • orbital lifetime reduction
  • reorbiting
  • data collection and measurement
  • autonomous deorbiting
  • international regulation.

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