STEPHANIE SY: We turn now to the skies, where it's not just the moon orbiting the Earth.

Laura Barron-Lopez reports on the growing problem of human made debris in space.

LAURA BARRON-LOPEZ: Mankind's trash litters our planet from local parks to the depths of the ocean.

But it's not just on Earth.

Debris from everything we've launched into space since the 1950s is clogging Earth's orbit, that space junk is threatening our technology down here and up there.

For more on what's at stake and how we can manage space junk going forward, we turn to Marcus Holzinger, Professor of Aerospace Engineering at the University of Colorado, Boulder.

Professor Holzinger, thank you so much for joining.

When we say space junk or space debris, what exactly are we talking about, and how much is in Earth's orbit?

MARCUS HOLZINGER, University of Colorado Boulder: Great question.

So when we're talking about space debris, we're talking about mostly anthropogenic or human made pieces of debris.

So these are defunct satellites, rocket bodies that have been expended and left up in orbit, as well as parts of spacecraft or parts of rocket bodies that have been up there now for an excess of 50 years, and even all the way up to the current time.

There are about 40,000 objects that we're tracking right now on orbit.

But there are a lot of objects that are much too small for us to actually track, and some estimates put that number between a half a million and a million objects up there, some almost the size of a softball, and of course, others getting down to the size of flecks of paint.

LAURA BARRON-LOPEZ: And how much of our technology and infrastructure depends on access to the satellites up there, and how does the space debris impact that?

MARCUS HOLZINGER: So there are a couple of really big important things to remember.

Number one is that our lives as they exist right now cannot exist without continued access to space and low Earth orbit.

Most of our weather prediction activities come from satellites taking pictures from low Earth orbit.

A lot of our infrastructure in terms of timing or GPS, also directly comes from spacecraft upon orbit.

If you can imagine a day without space, imagine a day where none of your credit cards work or.

You have no idea when to actually harvest food stuffs to avoid, for example, a great big thunderstorm or hail storm.

So really, it's no exaggeration to say that it is absolutely true that the modern way of life depends greatly upon continued access to space.

LAURA BARRON-LOPEZ: So essentially all of this junk up there could really eventually harm our day to day lives.

I mean, does the size of that space junk up there matter?

MARCUS HOLZINGER: It does there are a couple different ways to think about that.

In some orbits, the density of space debris is high enough to where the rate of close approaches or potential collisions is such that continued collisions would actually cause cascading creation of debris and further collisions that's famously known as the Kessler syndrome.

In most orbits that's currently not the problem, although, to be clear, a wide variety of spacecraft that are crude actively engage in avoidance maneuvers.

So for example, the International Space Station engages in a wide variety of avoidance maneuvers each and every year.

LAURA BARRON-LOPEZ: Private space companies now are launching satellites bigger than we've seen before, and many countries are looking to space to expand military capabilities.

So that means more launches and more debris up there.

What needs to be done to ensure that Earth's orbit is not continuously cluttered?

MARCUS HOLZINGER: There are combination of things that we can do.

So, number one, when we launch spacecraft, it behooves us to enable those spacecraft, or to build those spacecraft, so that they have the capability to de orbit themselves, or to put themselves into retirement or graveyard orbits.

Another thing that is really beneficial is when we have open communication between commercial and national operators in terms of what their current orbits are, so that more accurate collision avoidance maneuvers could be made.

It would be a really terrible thing to execute a collision of one's maneuver only to increase your risk from colliding with another object.

Now, the other things that we can do are more political in nature.

This is one of those problems where you have a number of commercial and national actors who all get benefit from placing objects up in orbit, up in space.

This is one of those shared commons problems where you have a resource or a capacity to put things up on orbit and marginal use by one actor can potentially degrade the environment.

And so it's something where we have to have a lot of open communications and hopefully consensus amongst international actors and corporations.

LAURA BARRON-LOPEZ: You're saying that this is political as well as a diplomatic issue.

So ultimately, whose problem is it to solve?

MARCUS HOLZINGER: Well, that's a great question.

It is something that the United States government takes very seriously, and there are active efforts to be good citizens on the part of the portion that the United States engages in in space.

So for example, the FCC has recently put out guidance to have spacecraft de orbit in five years, whereas previously the requirement had been 25 years.

So there are active things that we're doing here in the United States to be good international citizens and to keep space as free as possible of debris so that we can continue to enjoy the benefits that we currently get from space.

LAURA BARRON-LOPEZ: Professor, what happens if this ultimately is not tackled?

MARCUS HOLZINGER: If this is not tackled, if ultimately we end up having runaway levels of runaway densities of space objects in orbit, it just means that the expected lifetime of anything that we put up there is going to get shorter and shorter, and at some point it may not be economically viable to put things up on orbit just because they're not going to last long enough to provide any real benefit.

LAURA BARRON-LOPEZ: Professor Marcus Holzinger, thank you for your time.

MARCUS HOLZINGER: My pleasure, Laura.