Space junk is a huge problem, but this high-tech satellite net just might help


Experts hope to eliminate the debris before it becomes too risky to launch new satellites.

Image: The REMDEB satellite deployed in June from the International Space Station

The REMDEB satellite deployed in June from the International Space Station.NanoRacks, ISS and NASA

As some scientists try to clean up the world’s oceans and remove greenhouse gases from the atmosphere, others are tackling the problem of pollution in space. Defunct satellites, spent rocket parts and thousands of other pieces of human-made debris have accumulated in orbit around Earth in recent decades — and the problem is getting worse.

Now a consortium of universities and aerospace companies has begun testing a suite of technologies that could address the growing problem of space junk. On Sept. 16, scientists with the consortium successfully tested a net designed to snag orbiting debris and drag it down into Earth’s atmosphere, where it would burn up harmlessly.

The consortium’s refrigerator-sized RemoveDebris satellite deployed the spring-loaded net and captured a tiny cubesat that had been released for the experiment. Footage of the test shows the web-like net shooting out and trapping the mock space debris.

Guglielmo Aglietti, director of the Surrey Space Centre in England, said he was “very happy” with the test, adding that the net and the cubesat are expected to burn up in the atmosphere within a couple of months. The center leads the consortium, which also includes Airbus, ArianeGroup and other partners in Europe and South Africa.

In last week’s test, the RemoveDebris satellite released the net as it was deployed. But in a real space debris-grabbing mission, Aglietti said, the net would remain tethered to a “mothership” satellite, which would then reel it in and de-orbit it via some mechanism yet to be determined.

In February, Aglietti and his colleagues will use the satellite to test another debris-removal idea: a tethered harpoon that could latch onto space junk and remove it from orbit.

The RemoveDebris mission is focused on eliminating old satellites and other large debris — objects about the size of a bus and weighing a few tons — because they pose the biggest threat to the International Space Station and satellites in low-Earth orbit.

“If they collide with other things, they can explode and break into thousands of fragments,” Aglietti said of these objects. “Rather than trying to remove smaller bits, which would be technologically very challenging, we think the best thing is to remove large pieces — especially those in busy orbits.”

The U.S. Department of Defense tracks more than 500,000 pieces of space junk in orbit around Earth, including about 20,000 objects larger than a softball. As rocket launches continue and more debris is created, experts worry that we could reach a point where it’s too risky to launch new satellites.

Low Earth orbit (LEO), the region of space within 2,000 km of the Earth's surface, is the most concentrated area for orbital debris.
Low-Earth orbit, the region of space within 2,000 kilometers of the Earth’s surface, is the most concentrated area for orbital debris.NASA

“We’re at the tipping point,” said John Crassidis, a professor of mechanical and aerospace engineering at the University at Buffalo, who is not involved with the RemoveDebris mission. “If we don’t do something, it’s not going to be that much longer before there’s so much space junk and the probability of a collision is so great that nobody is going to want to insure satellites anymore.”

Crassidis called the recent test “fabulous,” but added that the RemoveDebris scientists must eventually show they can control debris after it’s been captured without destabilizing the RemoveDebris satellite itself.

“If you have an object that is rotating, that is going to affect your own satellite,” he said. “So, if the net is tethered, you have this momentum transferred between the two objects, and that can cause issues with trying to keep your satellite stable.”

Aglietti said even if the technology works, the bigger challenge will be navigating the politics and finding the money to mount clean-up initiatives. The RemoveDebris satellite cost $15 million, he said, but a real mission designed to remove space junk would likely cost significantly more.

“Technologically, we can do these things, but the difficulty will be to find the necessary funding and the necessary world cooperation that we need for this,” Aglietti said. “I think honestly the organizational and administrative problems are the main challenges, and not the technical challenges.”

Is SpaceX Being Environmentally Responsible?


Falcon Heavy’s flashy space car may not have been the best idea—for Mars

 

SpaceX via Twitter

SpaceX has now launched the most powerful spacecraft since the Apollo era—the Falcon Heavy rocket—setting the bar for future space launches. The most important thing about this reusable spacecraft is that it can carry a payload equivalent to sending five double-decker London buses into space—which will be invaluable for future manned space exploration or in sending bigger satellites into orbit.

Falcon Heavy essentially comprises three previously tested rockets strapped together to create one giant spacecraft. The launch drew massive international audiences—but while it was an amazing event to witness, there are some important potential drawbacks that must be considered as we assess the impact of this mission on space exploration.

But let’s start by looking at some of the many positives. Falcon Heavy is capable of taking 68 tonnes of equipment into orbit close to the Earth. The current closest competitor is the Delta IV heavy which has a payload equivalent of 29 tonnes. So Falcon Heavy represents a big step forward in delivering ever larger satellites or manned missions out to explore our solar system. For the purposes of colonizing Mars or the moon, this is a welcome and necessary development.

The launch itself, the views from the payload and the landing of the booster rockets can only be described as stunning. The chosen payload was a Tesla Roadster vehicle belonging to Space X founder and CEO Elon Musk—with a dummy named “Starman” sitting in the driver’s seat along with plenty of cameras.

This sort of launch spectacle gives a much needed public engagement boost to the space industry that has not been seen since the time of the space race in the 1960s. As a side effect this camera feed from the payload also provided yet another proof that the Earth is not flat—a subject about which Musk has previously been vocal.

The fact that this is a fully reusable rocket is also an exciting development. While vehicles such as the Space Shuttle have been reusable, their launch vehicles have not. That means their launches resulted in a lot of rocket boosters and main fuel tanks either burning up in the atmosphere or sitting on the bottom of the ocean (some are recovered).

This recovery massively reduces the launch cost for both exploration and scientific discovery. The Falcon Heavy has been promoted as providing a cost of roughly US$1,300 per kg of payload, while the space shuttle cost approximately $60,000 per kg. The impact this price drop has for innovative new space products and research is groundbreaking. The rocket boosters on this test flight had a controlled and breathtakingly simultaneous landing onto the launch pad.

So what could possibly be wrong with this groundbreaking test flight? While visually appealing, cheaper and a major technological advancement, what about the environmental impact? The rocket is reusable, which means cutting down the resources required for the metal body of the rocket. However, the mass of most rockets are more than 95% fuel. Building bigger rockets with bigger payloads means more fuel is used for each launch. The current fuel for Falcon Heavy is RP-1 (a refined kerosene) and liquid oxygen, which creates a lot of carbon dioxide when burnt.

The amount of kerosene in three Falcon 9 rockets is roughly 440 tonnes and RP-1 has a 34 percent carbon content. This amount of carbon is a drop in the ocean compared to global industrial emissions as a whole, but if the SpaceX’s plan for a rocket launch every two weeks comes to fruition, this amount of carbon (approximately 4,000 tonnes per year) will rapidly become a bigger problem.

The car test payload is also something of an issue. The vehicle has been scheduled to head towards Mars, but what has not been made clear is what is going to happen to it afterwards. Every modern space mission is required to think about clearing up after itself. In the cases of planetary or lunar satellites this inevitably results in either a controlled burn-up in the atmosphere, or a direct impact with the body they orbit.

Space debris is rapidly becoming one of the biggest problems we face—there are more than 150 million objects that need tracking to ensure as few collisions with working spacecraft as possible. The result of any impact or degradation of the car near Mars could start creating debris at the red planet, meaning that the pollution of another planet has already begun.

Space Junk
Space Junk 

However, current reports suggest that the rocket may have overshot its trajectory, meaning the vehicle will head towards the asteroid belt rather than Mars. This is probably going to mean a collision is inevitable. The scattering of tiny fragments of an electric vehicle is pollution at the minimum—and a safety hazard for future missions at worst. Where these fragments end up will be hard to predict—and hence troublesome for future satellite launches to Mars, Saturn or Jupiter. The debris could be drawn by the gravity of Mars, asteroids or even swept away with the solar wind.

What is also unclear is whether the car was built in a perfect clean room. If not there is the risk that bacteria from Earth may spread through the solar system after a collision. This would be extremely serious, given that we are currently planning to search for life on neighbouring bodies such as Mars and Jupiter’s moon Europa. If microorganisms were found there we may never know whether they actually came from Earth in the first place.

Of course, these issues don’t affect my sense of excitement and wonder at watching the amazing launch. The potential advantages of this large-scale rocket are incredible, but private space firms must also be aware that the potential negative impacts (both in space and on Earth) are just as large.

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