Look out, it's the space cops! Tiny satellites developed to patrol Earth's orbit and monitor space junk



Nano satellites will be able to move satellites that are headed for a collision

Currently over 20,000 pieces of 'space junk' are tracked

System could avoid accidental collisions

Even in space, there is no escape from traffic cops.

A team of Lawrence Livermore National Laboratory are building a swarm of tiny cop-sats that will monitor and help the vast amounts of traffic in orbit.

They will create the most accurate maps of space junk ever created to avoid collisions.

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It is estimated that there are as many as 370,000 pieces of space junk floating in Earth's orbit, travelling at speeds of up to 22,000 mph



WHAT IS SPACE JUNK?

Since the first object, Sputnik One, was launched into space 53 years ago, mankind has created a swarm of perhaps tens of millions of items of debris. The rubbish circling the planet comes from old rockets, abandoned satellites and missile shrapnel. There are around 22,000 objects in orbit that are big enough for officials on the ground to track and countless more smaller ones that could do damage to human-carrying spaceships and valuable satellites. It is estimated that there are as many as 370,000 pieces of space junk floating in Earth's orbit, traveling at speeds of up to 22,000 mph. One major source of debris in the past was the testing of anti-satellite weapons carried out by both the U.S. and Soviet Union in the 1960s and 1970s.

Accidental events have also contributed to the problem. In February 2007 for instance, a Russian Briz-M booster stage exploded in orbit over South Australia.

The scientists have already tested their system in the lab.



They used a series of six images over a 60-hour period taken from a ground-based satellite to prove that it is possible to refine the orbit of another satellite in low earth orbit.



'Eventually our satellite will be orbiting and making the same sort of observations to help prevent satellite-on-satellite and satellite-on-debris collisions in space,' said Lance Simms, lead author of a paper appearing in an upcoming edition of the Journal of Small Satellites.



Collisions in space of satellites and space debris have become increasingly problematic.



To help satellite operators prevent collisions in space, the Space-Based Telescopes for Actionable Refinement of Ephemeris (STARE) mission, which will consist of a constellation of nano-satellites in low earth orbit, intends to refine orbits of satellites and space debris to less than 100 meters.



In their test, using the ground-based satellite, the Livermore team refined the orbit of the satellite NORAD 27006, based on the first four observations made within the initial 24 hours, and predicted NORAD's trajectory to within less than 50 meters over the following 36 hours.



By refining the trajectory of NORAD 27006 with their ground-based payload, the team believes they will be able to do the same thing for other satellites and debris once their payload is orbiting earth.



The tools and analysis used to capture the images of NORAD 27006 and refine its orbit are the same ones that will be used during the STARE mission.



'This leads credence to the capability of STARE to accomplish its mission objectives,' De Vries said.



Accurately predicting the location of a satellite in low earth orbit at any given time is difficult mainly because of the uncertainty in the quantities needed for the equations of motion.



Atmospheric drag, for instance, is a function of the shape and mass of the satellite as well as the density and composition of the unstable atmosphere.



These uncertainties and the incompleteness of the equations of motion lead to a quickly growing error in the position and velocity of any satellite being tracked in low earth orbit.



To account for these errors, the Space Surveillance Network (SSN) must repeatedly observe the set of nearly 20,000 objects it tracks; however, positional uncertainty of an object is about 1 kilometer.

This lack of precision leads to approximately 10,000 false alarms per expected collision.



With these large uncertainties and high false alarm rates, satellite operators are rarely motivated to move their assets after a collision warning is issued.



From left to right: Brian Bauman, Vincent Riot, Darrell Carter, Lance Simms and Wim De Vries have developed and tested land-based mini-satellites that eventually will be used in space to help control traffic in space.



The STARE mission aims to reduce the 1 kilometer uncertainty down to 100 meters or smaller, which will in turn reduce the number of false alarms by roughly two orders of magnitude, Riot said.



In the case of the Livermore team, they were able to reduce the uncertainty to 50 meters, well below the 100-meter goal.



Space might seem like a vast, empty expanse, but in reality the area surrounding Earth has become congested with junk.

This junk – which can include anything from old rockets, abandoned satellites to missile shrapnel - will soon make it difficult for spacecraft to leave the planet.

Japanese researchers are also investigating the problem.

Japan Aerospace Exploration Agency (JAXA) has now teamed up with Nitto Seimo, a company that manufactures fishing equipment, to build a ‘magnetic net’ that can fish out space debris.

The first test of this equipment is scheduled for late February when a Japanese rocket will be launched to deploy a satellite made by researchers at Kagawa University.

Once the satellite is in orbit, it will release a 300 metre-long wire net that will then generate a magnetic field strong enough to attract some of the debris in orbit.

Both the net and its contents will burn up as they enter Earth's atmosphere.

Based on a data archive, each miniature sphere in this image represents an existing object orbiting in space. There are around 22,000 objects in orbit that are big enough for officials on the ground to track

The possibility of a satellite crashing into a hunk of space debris has worried scientists for years.

One collision could send thousands of pieces of debris spinning out, potentially destroying other satellites.

There are around 22,000 objects in orbit that are big enough for officials on the ground to track and countless more smaller ones that could do damage to human-carrying spaceships and valuable satellites.

Television signals, weather forecasts, global-positioning navigation and international phone connections are just some of the services at risk.

A recent Nasa report said that the amount of space junk orbiting earth had reached a 'tipping point'.

In 2009 there was a major crash between a U.S. communications satellite and a defunct Russian military probe over Siberia.

The collision at speeds of at least 15,000mph created a cloud of 1,500 pieces of space junk that the International Space Station then had to manoeuvre to avoid.

A Chinese missile test in 2007 left 150,000 pieces of junk in the atmosphere.