Space debris, also commonly referred to as space junk, is a growing concern – in space and on Earth. European Space Agency (ESA) officials define space debris as “all non-functional, human-made objects, including fragments and elements thereof, in Earth orbit or re-entering into Earth's atmosphere.” The space environment is becoming more congested, increasing the potential for collisions with debris that could potentially damage satellites that provide safety-critical and mission-critical capabilities, threaten the lives of astronauts aboard spacecraft, or reenter Earth’s atmosphere.
“A huge amount of debris has progressively been generated since the beginning of the space era. Most of the objects launched into space are still orbiting the Earth and today these objects and their by-products represent a threat both in space and on Earth,” NASA officials explain.
“In space, debris can lead to collisions and potential damage to operational satellites, which may affect services on earth,” NASA officials add. “Collisions in space can be very hard to predict and can also be very dangerous. Uncontrolled objects flying in space may cause problems for operational spacecraft. Two objects colliding in space may lead to a large amount of smaller very fast-moving debris. The worst-case scenario is that one collision leads to another and eventually all the spacecraft relied on for Internet connection, e-mail, global positioning system (GPS) navigation, and the use of mobile phones are affected.”
RemoveDEBRIS “aims to demonstrate key technologies for active debris removal by performing in-orbit demonstrations representative of an active debris removal mission. The specific key technologies to be demonstrated as part of this project are: capture methods including a net and a harpoon; rapid de-orbiting technology demonstration via the drag sail; and proximity detection for rendezvous operations using vision-based navigation,” NASA officials say. “This project helps make spaceflight safer for spacecraft and, in the case of those with crew, the people onboard.” (Stay tuned for an announcement from SAE International on space safety.)
RemoveDEBRIS, being acclaimed as one of the world’s first attempts to address the build-up of dangerous space debris orbiting Earth, launched to the ISS aboard the 14th SpaceX Commercial Resupply Mission, on a SpaceX Falcon 9 rocket from Kennedy Space Center, Fla., in April.
Surrey Satellite Technology Ltd. (SSTL), a spin-off of the University of Surrey now majority-owned by Airbus Defence and Space, in England built the RemoveDEBRIS satellite, which was deployed via the commercially developed Kaber Microsatellite Deployer from NanoRacks in Webster, Texas.
A consortium of space companies and research institutions, led by the Surrey Space Centre at the University of Surrey and funded in part by the European Union (EU) Seventh Framework Program under a grant agreement, helped to design and develop the satellite. The consortium includes: Airbus, Ariane Group, and Inria in France; SSTL in England; Innovative Solutions In Space in the Netherlands; CSEM in Switzerland; and Stellenbosch University in South Africa.
Astronauts launched the RemoveDEBRIS satellite from the Japanese Experiment Module (JEM), nicknamed as Kibo, which translates to “hope” in English. Kibo, Japan's first human-rated space facility and the Japan Aerospace Exploration Agency's (JAXA's) first contribution to the ISS program, is designed to facilitate scientific research activities on orbit. JEM provides extensive opportunities for space environment utilization, officials say, and relies on air, power, data, and cooling fluid resources necessary for on-orbit operation from the U.S. segment of the ISS.
Japanese Defense Minister Itsunori Onodera pledged to work with the JAXA to clean up dangerous debris floating in space on his July 2 visit to Tsukuba Space Center, JAXA’s headquarters in Tsukuba Science City. “We will proactively get involved with monitoring the situation in space so that we can use it safely,” Onodera is quoted as saying. “I hope the Defense Ministry, as well as the Self-Defense Forces, will advance the exploration and utilization of cosmic space for the purpose of guaranteeing security through my visit to JAXA.”
The RemoveDEBRIS mission will perform four experiments, which will be tested on two CubeSats to-be-deployed from the larger satellite, acting as artificial targets. These experiments include the first harpoon capture in orbit and a net that will be used on a deployed target. The team will also test a vision-based navigation system that uses cameras and light detection and ranging (LIDAR) technology to observe CubeSats that will be released from the main spacecraft. Finally, the RemoveDEBRIS craft will deploy a large drag sail that will cause the orbit of the spacecraft to decay rapidly until it is destroyed in the Earth’s atmosphere.
“RemoveDEBRIS is demonstrating some extremely exciting active debris removal technologies that could have a major impact to how we manage space debris moving forward,” says NanoRacks External Payloads Manager Conor Brown. “This program is an excellent example of how small satellite capabilities have grown and how the space station can serve as a platform for missions of this scale.”
Work is shared amongst members of the consortium includes:
- Mission and consortium coordination – Surrey Space Centre (U.K.)
- Satellite system engineering ASF (France)
- Platform and avionics – SSTL (U.K.)
- Harpoon – Airbus (UK)
- Net – Airbus (Germany)
- Vision-based navigation – CSEM (Switzerland)/INRIA/Airbus (France/Toulouse)
- CubeSat dispensers – Innovative solutions in space (Holland)
- Target CubeSats – Surrey Space Centre (U.K.)/STE
- Dragsail – Surrey Space Centre (U.K.)
The SSC academic team on this project includes: Prof. G. Aglietti, Prof. C. Underwood, and Dr. C. Bridges. The RemoveDebris consortium has been led by Simon Fellowes.
The sequence of launch is described as:
The platform is packed in specialist boxes which are launched to the ISS.
The boxes are unpacked by the astronauts and installed on a slide table.
The slide table moves into the ISS Japanese module and a special robotic arm grapples the platform and moves it outside the ISS.
The arm then releases the platform in a very specific direction and the mission begins.
As of April 2017, more than 290 breakups in orbit have been recorded since 1961. Most were explosions of satellites and upper stages – fewer than 10 involved accidental and intentional collisions. (Image courtesy ESA/ID&Sense/ONiRiXEL.)
Now that it has been deployed, it will begin its mission, with the initial phases to include testing the pair of CubeSats that are on board. The first, called DebrisSat 1, has an inflatable balloon that RemoveDEBRIS will attempt to capture with a net, testing its debris-capturing capabilities. Once this is complete the second CubeSat, DebrisSat 2 (DS2), will be deployed and use its vision-based navigation (VBN) system to track DS2’s movement after it has been released, describes an engineer at VPT Inc., part of the HEICO Electronic Technologies Group and a provider of power conversion solutions for use in avionics, military, space, and industrial applications with offices in Blacksburg, Va., and Bothell, Wash.
After these tests, RemoveDEBRIS will test its harpoon by attempting to penetrate and reel in a target that will extend from its frame. Finally, the spacecraft will release its inflatable drag sail, which will work as an airbrake to help the spacecraft deorbit safely. Upon re-entry to the Earth’s atmosphere, it will burn up, VPT’s engineer affirms. “With parts on board, VPT is proud to be a part of this vital mission to help remove hazardous space debris and look forward to watching this and future related missions unfold.”
ESA's Space Debris Office at ESOC in Darmstadt, Germany, offers the following space debris figures, confirmed correct as of Jan. 2017:
Rocket launches since the start of the space age in 1957: About 5,250
Satellites these rocket launches have placed into Earth orbit: About 7,500
Number of these still in space: About 4,300
Number of these still functioning: About 1,200
Debris objects regularly tracked by the US Space Surveillance Network and maintained in their catalogue: About 23,000
Estimated number of breakups, explosions, and collision events resulting in fragmentation: More than 290
Total mass of all space objects in Earth orbit: About 7,500 tonnes
Number of debris objects estimated by statistical models to be in orbit:
- 29,000 objects >10 cm
- 750,000 objects from 1 cm to 10 cm
- 166 million objects from 1 mm to 1 cm
Courtney E. Howard is editorial director and content strategist at SAE International, Aerospace Products Group. Contact her by e-mail at email@example.com.
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Images courtesy NASA, NanoRacks, JAXA, ESA, and Airbus. Continue reading »