Alibi V.24 No.25 • June 18-24, 2015 


The People in Your Neighborhood

Dr. Moriba Jah, Space Garbage Man

Space Garbage Man
Robert Maestas

In 1957, Sputnik became the very first man-made object to enter orbit around the Earth. Since then, it has been followed by thousands of other objects, including satellites, rockets, and space stations. Many of these objects have been abandoned after becoming nonfunctional, adding to an estimated half-million pieces of so-called “space debris,” which range in size from chips of paint to broken-down satellites. Dr. Moriba Jah, 44, is an astrodynamicist working as a Mission Lead in Space Situational Awareness for the Air Force Research Laboratory at Kirtland Air Force Base. It is his job to help track some 22,000 of these pieces of space junk.

Can you explain your role as a “Space Garbage Man”?

Well, more formally I’m involved in something called Space Situational Awareness. Basically, its purpose is to try to deliver a body of evidence of behaviors that you can assign to specific threats or hazards in space to decision makers. I don’t try to associate myself with whatever decisions they are making—I just provide scientific evidence of specific behaviors [of objects in orbit].

Does orbital debris affect the everyday person in any way?

If a piece of debris hits a satellite that routes banking information, then that would be a bad day for the everyday person. If a piece of debris hits one of the Global Positioning Systems that we use for maps on our iPhone, then it would be a noticeable impact.

What kinds of things affect the behavior of the objects out there?

The main thing that drives how things behave is gravity. It’s the dominant force. But then size, shape, material properties, orientation—all of these things are influenced by what are called non-conservative or non-gravitational forces. Depending on how much solar activity is going on, photons are coming from the sun and pushing things around. There are also charged particle environments where objects can get charged, and then when they move through magnetic fields, they can behave differently. Thermal effects can create a hot side and a cold side of an object, which creates flux and results in a tumbling effect. So there are all these different forces acting on the objects, and it’s the non-gravitational ones that make it so difficult to predict behavior because they require knowing more about the specific objects.

Keep as many eyes on the sky as possible so that we can understand it and preserve the space environment for generations to come.

Dr Moriba Jah

How do you collect your data?

We are working with radar and telescopes that just see dots in the sky. So from a collection of dots in the sky, we have to be able to say “Okay. All those dots are the same thing and because of the way it’s behaving, it’s this size, this shape.” There’s a lot of complex science that goes on behind collecting pictures of dots and trying to infer all of these characteristics so we can predict how these things will behave.

What sort of applications does this research have?

Our space environment is becoming more and more polluted, and the point of my work is to be able to predict when collisions will occur. If we can predict a collision between something that works and something that doesn’t work, or two things that work, we can move them out of the way.

Even though this is an ongoing project, is there an ultimate goal that this knowledge can be used for?

The ultimate goal is the long-term sustainability of space activities and the preservation of the space environment as a free and peaceful space. Also, if we can really understand space debris, how it moves and where it comes from, we can educate other countries on how to be good stewards of the space environment because there are many nations that are becoming new actors in space, and we don’t want them to repeat the same mistake that others have made.

Do we currently clean up any of the junk out there?

No, we just monitor it right now. There have been many discussions within the United Nations about how to maybe clean up the space environment, but it’s currently neither economically nor politically feasible.

Does space debris eventually break down or experience orbital decay naturally?

Things that are in low Earth orbit (about 200 km) will eventually decay. On average there are about two to three objects that reenter the atmosphere and burn up per day. That’s the natural cleansing process, but the majority of the junk is above the sensible atmosphere, so it’s pretty much there ad infinitum.

Do people have to constantly change the flight paths of satellites to avoid collisions with space junk, or are most of the trajectories pretty stable?

On average at the International Space Station, there are about a dozen collision warnings per year where they actually have to maneuver the space station out of the way. So it’s not constant, but it does happen periodically.

What is the coolest thing that you’ve tracked?

The coolest thing is actually a multilayered insulation cover that was on a cooler connected to a satellite called MSG-2. Technically, it’s called “mission-related” junk because it was a necessary part of the satellite that had to be popped off before it got to its destination. One of the guys on the project gave me all the information about that specific object so that I could sort of “tune” my algorithms as I tracked it. So it’s been used as a calibration object in our research.

When you were a child, did you want to be an astronaut when you grew up?


Is that what got you started in all this space stuff?

Not really ‘cause I wanted to be a Greyhound bus driver too!

What really started you on this path of study?

I went to a small university in Arizona called Embry-Riddle Aeronautical University, and my mentor there had worked on space debris when he was in graduate school. He inspired me to get into this whole space business.

What’s your advice for the world?

Keep as many eyes on the sky as possible so that we can understand it and preserve the space environment for generations to come.