We noticed you're browsing in private or incognito mode.

To continue reading this article, please exit incognito mode or log in.

Not an Insider? Subscribe now for unlimited access to online articles.

Emerging Technology from the arXiv

A View from Emerging Technology from the arXiv

Junk-Eating Rocket Engine Could Clear Space Debris

The risks associated with space debris are rising. An efficient way to clear the skies of junk is desperately needed, and a team of Chinese engineers think they have the answer.

  • December 3, 2015

At 16:56 UTC on August 29, 2009, an Iridium communications satellite suddenly fell silent. In the hours that followed, the U.S. Space Surveillance Network reported that it was tracking two large clouds of debris—one from the Iridium and another from a defunct Russian military satellite called Cosmos 2251.

The debris was the result of a high-speed collision, the first time this is known to have happened between orbiting satellites. The impact created over 1,000 fragments greater than 10 centimeters in size and a much larger number of smaller pieces. This debris spread out around the planet in a deadly cloud. 

Space debris is a pressing problem for Earth-orbiting spacecraft, and it could get significantly worse. When the density of space debris reaches a certain threshold, analysts predict that the fragmentation caused by collisions will trigger a runaway chain reaction that will fill the skies with ever increasing numbers of fragments. By some estimates that process could already be underway.

An obvious solution is to find a way to remove this debris. One option is to zap the larger pieces with a laser, vaporizing them in parts and causing the leftovers to deorbit. However, smaller pieces of debris cannot be dealt with in this way because they are difficult to locate and track.

Another option is send up a spacecraft capable of mopping up debris with a net or some other capture process. But these missions are severely limited by the amount of fuel they can carry.

Today, Lei Lan and pals from Tsinghua University in Beijing, China, propose a different solution. Their idea is to build an engine that converts space debris into propellant and so can maneuver itself almost indefinitely as it mops up the junk.

Their idea is simple in principle. At a high enough temperature, any element can be turned into a plasma of positive ions and electrons. This can be used as a propellant by accelerating it through an electric field.

The details are complex, however. In particular, the task of turning debris into a usable plasma is not entirely straightforward.

Lei and co focus their efforts on debris that is smaller than 10 centimeters in size, the stuff that laser ablation cannot tackle. Their idea is to capture the debris using a net and then transfer it to a ball mill. This is a rotating cylinder partially filled with abrasion-resistant balls that grind the debris into powder. 

This powder is heated and fed into a system that separates positively charged ions from negatively charged electrons. The positive ions then pass into a powerful electric field that accelerates them to high energy, generating thrust as they are expelled as exhaust. The electrons are also expelled to keep the spacecraft electrically neutral.

Of course, the actual thrust this produces depends on the density of debris, the nature of the powder it produces, on the size of the positive ions, and so on. All this is hard to gauge.

And while the spacecraft does not need to carry propellant, it will need a source of power. Just where this will come from isn’t clear. Lei and co say that solar and nuclear power will suffice but do not address the serious concerns that any nuclear-powered spacecraft in Earth orbit will generate.

Nevertheless, the work provides food for thought. Space debris is an issue that looks likely to get significantly worse in the near future. It is an area where new ideas are desperately needed before the next big collision fills Earth’s orbits with even more debris.

Ref: arxiv.org/abs/1511.07246 : Debris Engine: A Potential Thruster for Space Debris Removal

Get stories like this before anyone else with First Look.

Subscribe today
Already a Premium subscriber? Log in.

Uh oh–you've read all of your free articles for this month.

Insider Premium
$179.95/yr US PRICE

Want more award-winning journalism? Subscribe to Insider Plus.
  • Insider Plus {! insider.prices.plus !}*

    {! insider.display.menuOptionsLabel !}

    Everything included in Insider Basic, plus the digital magazine, extensive archive, ad-free web experience, and discounts to partner offerings and MIT Technology Review events.

    See details+

    What's Included

    Unlimited 24/7 access to MIT Technology Review’s website

    The Download: our daily newsletter of what's important in technology and innovation

    Bimonthly print magazine (6 issues per year)

    Bimonthly digital/PDF edition

    Access to the magazine PDF archive—thousands of articles going back to 1899 at your fingertips

    Special interest publications

    Discount to MIT Technology Review events

    Special discounts to select partner offerings

    Ad-free web experience

You've read all of your free articles this month. This is your last free article this month. You've read of free articles this month. or  for unlimited online access.