Space junk is making low Earth orbit crowded. (Image: © Johan Swanepoel/Shutterstock) Space junk is making low Earth orbit crowded. (Image: © Johan Swanepoel/Shutterstock)

Space junk: Astronomers worry as private companies push ahead with satellite launches

Since the launch of Sputnik 1 in 1957, the lower orbit around the Earth has become an increasingly congested environment with more than 2,200 satellite launches to date. Those satellites — along with launch vehicle components and debris from mechanical disintegration, collisions and explosions — now fill this region with a "fog" of space debris.

And it's getting busier. In the last few weeks, SpaceX has launched 60 new satellites as part of its Starlink program. This brings the total to more than 500 Starlink satellites in low Earth orbit as part of a program that aims to bring cheap, satellite-based internet access to everyone. Eventually, this program could place nearly 12,000 satellites in orbit around the Earth.

With Amazon, Canada's Telesat and others planning satellite constellations of similar scale, low Earth orbit is becoming ever more crowded.

The debris ranges in size from a few microns to many meters. Stuart Grey, an aerospace engineer at the University of Strathclyde, has produced a stunning visualization that highlights the more than 20,000 objects over 4 inches (10 centimeters) in size now orbiting the Earth (see video above). But there are many millions of particles 0.04 inches (1 millimeter) in size and smaller.

Closing our window on the universe?

Amateur astronomers are already expressing concern over the increasing number of bright, moving objects in the night sky. But the worry is perhaps much greater for the professionals.

Crowding in low Earth orbit has inevitable consequences for ground-based astronomers. Bright surfaces on satellites can reflect rays from the sun — giving rise to a burst of sunlight directed towards the surface of the Earth. Such intense bursts of light are much stronger than the weak light sources typically being observed by astronomers and will impede observations of distant objects in space.

Billions have already been spent on existing optical telescopes, and many more billions will be poured into new platforms in the next decade, such as the European Extremely Large Telescope being built on the Atacama plateau in Chile. There is intense competition for observing time on such resources, so any potential threat from satellite reflections must be taken seriously as they may make some of the observations driving our understanding of the evolution of the universe impossible.

SpaceX has assured the public that Starlink will not contribute to this problem and says it has been taking steps to mitigate the impacts of its satellites on observational astronomy — even to the extent of testing whether a black coating on its satellites can reduce visibility, and adjusting some of the satellites' orbits if necessary.

With some 3% of its planned constellation launched, SpaceX is at least responding to the concerns raised by astronomers. Hopefully other agencies planning satellite constellation launches will also be upfront with their plans to reduce this serious problem to astronomical observation.

But crowding in low Earth orbit also has consequences for satellites and other space vehicles, including those designed to carry humans. To achieve orbit, satellites seek a balance between their speed and the effect of Earth’s gravity on them. The speed with which a satellite must travel to achieve this balance depends on its altitude above Earth. The nearer to Earth, then the faster the required orbital speed.

At an altitude of 124 miles (200 kilometers), the required orbital velocity is a little more than 17,000 miles per hour (about 7.4 km/s). Any object shed by a satellite or other vehicle in orbit will maintain the same orbital speed. Collisions between such objects can therefore occur at combined speeds of potentially up to 34,000 mph at 124 miles (if it is head-on). The effects of such impacts can be serious for astronauts and space stations — as the dramatic opening scenes of the 2013 movie "Gravity" depict.

There is impact shielding on satellites and space vehicles which is designed to stop objects smaller than 0.4 inches (1 cm) crashing into them. At best, the shielding will do so — though the electromagnetic impulse created may interfere with electronic systems. At worst, larger pieces of space junk could penetrate the vehicles. This could result in internal damage and disintegration that threaten the safety of the mission.

Space agencies such as NASA and ESA have therefore established orbital debris research programs to observe such debris and develop strategies to control its effects.

There is little doubt that, with the increasing use and commercialization of space, we boost the risk of catastrophic events associated with orbital debris. Agencies, both state and commercial, must recognize this and support efforts to reduce the likelihood of such events by taking steps to remove existing debris and reduce the potential for further debris by removing redundant satellites and other space vehicles. For example the RemoveDEBRIS satellite uses an on-board harpoon to capture junk.

Only when we resolve the problem of space junk will our window on, and pathway to, space be truly fully open.

The views expressed are those of the author and do not necessarily reflect the views of the publisher. 

This article was originally published at The Conversation. The publication contributed the article to's Expert Voices: Op-Ed & Insights. Read the original article.

Video can be accessed at source link below


By Martin McCoustra / ScotCHEM Chair in Chemical Physics, Heriot-Watt University

Research Interests:
My principle research interests are in the mechanism, dynamics and kinetics of chemical processes involving surfaces. This encompasses a range of activities from fundamental studies of the nuclear and electronic dynamics in collision- and photon-promoted processes through investigations of surface physics and chemistry relevant to understanding the role of gas-grain interactions in the interstellar medium to developing a novel mass spectrometry technique for the study of surfaces, plasma-assisted desorption/ionisation mass spectrometry (PADI-MS).

I am particularly interested in the application of surface science methods to the study of physics and chemistry related to the chemical evolution of the universe; the formation of molecules, their astrochemical transformations and the evolution of the chemical potential for life. In this respect, I work closely with astronomers, molecular astrophysicists and others engaged in the study of our chemica cosmos.

Research Grants Received:
Over the course of my career, my research has been funded principally through UK Research Council awards and a large EU Framework award to support a pan-European training network to a total value in excess of £11M (LASSIE - Laboratory Astrochemical Surface Science in Europe - FP7/2007-2013 under grant agreement number 238258) which I coordinated from 2010 to 2014.

Publications, Presentations and Conference Organisation:
To summarise, my publications list comprises 74 contributions to refereed academic journals in print, 120 contributions to conferences of which 18 are invited contributions to international meetings, 13 contributions to Central Facility annual reports, DRA reports or CEC reports, 10 books and contributions to edited books, 3 papers in popular journals and 3 reviews of academic books. My h-index is currently 21.

In addition, I have given numerous seminars at other institutions; including the prestigious van Marum Colloquium at the University of Leiden, which of the over 60 delivered only 6 have been given by UK scientists. I have also made presentations at numerous events run by the Royal Society, the Royal Society of Chemistry and the Institute of Physics. I have also been involved in organising at least 20 national and international meetings; Chaired the successful Faraday Discussion Number 141 on water at interfaces and will chair Faraday Discussion Number 168 on solid state and surface astrochemistry, chaired the combined the European Conference on Surface Science and European Physical Society Condensed Matter Meeting in Edinburgh in 2012 and co-chaired a number of parallel meetings at that time and the IVC in Paris in 2013.

Public Engagement and Schools Outreach:
I have been active in PE and outreach since my first appointment. At UEA, I coordinated the Shell-Royal Institution Masterclasses in Spectroscopy for 6th Form Students and was involved in developing a short residential programme for teachers of chemistry. In Nottingham, I proposed and helped to develop the Stars ‘r’ Us! Exhibit in astrochemistry for the 2004 Royal Society Summer Exhibition, at which it was viewed as amongst the most popular of the exhibits. The materials prepared by the team were made available on CD, and remain so today, and many teachers across the UK have taken the opportunity to acquire this material from the SRU team. The team’s experience in assembling and operating the exhibit that July was later reported in the Royal Astronomical Society journal Astronomy & Geophysics [see Viti et al., Astron. Geophys., 2004, 45, 6.22-6.24] and via the SRU website at In addition, the Royal Society of Chemistry invited the team to prepare a short paper on the science themes of SRU for their journal Education in Chemistry [see McCoustra et al., Educ. Chem., 2005, 42, 153-155]. This paper, along with other papers from that journal on similar themes was later assembled into a special teachers pack by the SRU team, with the full support of the journal concerned, as part of their presence at the Royal Society Scottish Summer Exhibition in September 2006.

Following on from the Royal Society Summer Exhibition in 2004, there was a veritable whirlwind of activity as SRU took on a life of its own. Invitations flowed in to participate in large scale public outreach events;

• London – National Science Week, National Maritime Museum, Greenwich, March 2005 and 2006.
• Athens – Einstein Year, June 2005, (at the invitation of the British Council, Athens).
• Chelmsford – International Scout Jamboree, July 2005, (invited by Scout Association following a visit to the Royal Society Summer exhibition 2004 by the organiser of the Scout Jamboree).
• Paris – Village des Science, October 2005, (at the invitation of the British Council, Paris).
• Shopping Malls in Newcastle, Manchester, Brighton, Nottingham – UK Chemistry Week Shopping Centre Tour, November 2005 (on behalf of the RSC).
• Edinburgh – International Science Festival at the Dynamic Earth Centre, April 2008, 2009 and 2011.
• Brussels – Astrochemistry: The Cradle of Life, Natural History Museum, July 2011
• Cheltenham – Science Festival, July 2013

Those events have meant that the exhibit has been seen by in excess of 75,000 members of the public across Europe and the public have seen the enthusiasm with which the team and their research staff operate SRU.

With my move to Heriot-Watt, my SRU activities continued and in addition I took on the role of Outreach Coordinator for Chemistry and Chair of the Outreach Group in Engineering and Physical Sciences. I deliver typically over a dozen lectures in schools each year and manage in-house activities including the Royal Society of Edinburgh Masterclasses in Science and Technology (for junior high school pupils), the Salters’ Festivals of Chemistry at Heriot-Watt, and our week long residential course for chemistry teachers. I also act as an interface for RSC (Top of the Bench and the Young Analyst’s Competition) and Royal Academy of Engineering (Headstart and Dragofly) events.

(Source:; June 30, 2020;
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