That's exactly my concern. Wiping out several billion dollars of satellite hardware is a potential cost of SRM that hasn't been considered - even if a reduction in space junk was a benefit. Alan could maybe add that to an update to his 20 reasons article.
PS although space mirrors could be sited in LEO, it's more likely they'll be placed at L1, which is unaffected as it's a) far away b) stationary relative to the earth - sun axis. Andrew On Fri, 5 Oct 2018, 15:02 Douglas MacMartin, <[email protected]> wrote: > Of course, SRM with stratospheric aerosols would heat the stratosphere and > more than offset the effect of CO2 on low-orbit atmospheric drag… > > > > > > > > *From:* [email protected] [mailto: > [email protected]] *On Behalf Of *Andrew Lockley > *Sent:* Friday, October 05, 2018 9:14 AM > *To:* geoengineering <[email protected]>; Carbon Dioxide > Removal <[email protected]> > *Subject:* [CDR] Huh? Carbon Dioxide Emissions Raise Risk of Satellite > Collisions - Scientific American > > > > Poster's note: none of the CDR / SRM papers I've seen have assessed this > risk. > > > > > https://www.scientificamerican.com/article/huh-carbon-dioxide-emissions-raise-risk-of-satellite-collisions/ > > > > Scientific American <https://www.scientificamerican.com/> > > SUBSCRIBE > <https://www.scientificamerican.com/store/subscribe/scientific-american-space-physics-magazine/> > > Close > > Search > > · THE SCIENCES <https://www.scientificamerican.com/the-sciences/> > > · MIND <https://www.scientificamerican.com/mind/> > > · HEALTH <https://www.scientificamerican.com/health/> > > · TECH <https://www.scientificamerican.com/tech/> > > · SUSTAINABILITY > <https://www.scientificamerican.com/sustainability/> > > · EDUCATION <https://www.scientificamerican.com/education/> > > · VIDEO <https://www.scientificamerican.com/video/> > > · PODCASTS <https://www.scientificamerican.com/podcasts/> > > · BLOGS <https://blogs.scientificamerican.com/> > > · STORE <https://www.scientificamerican.com/store/> > > · Subscribe > <https://www.scientificamerican.com/store/subscribe/scientific-american-space-physics-magazine/> > > · Current Issue > <https://www.scientificamerican.com/magazine/sa/2018/10-01/> > > · Cart <https://www.scientificamerican.com/store/shopping-cart/> > > · Sign In <https://www.scientificamerican.com/my-account/login/> > > · Register > <https://www.scientificamerican.com/my-account/register/> > > [image: Climatewire] > > *SPACE <https://www.scientificamerican.com/space/>* > Huh? Carbon Dioxide Emissions Raise Risk of Satellite Collisions > > European agency might actively remove space junk to reduce costly crashes > > · By John Fialka > <https://www.scientificamerican.com/author/john-fialka/>, E&E News > <https://www.scientificamerican.com/author/e-e-news/> on October 4, 2018 > > [image: Huh? Carbon Dioxide Emissions Raise Risk of Satellite Collisions] > > *Credit: Jose Luis Stephens Getty Images > <https://www.gettyimages.com/detail/photo/satellite-against-earth-royalty-free-image/1032650858>* > > ADVERTISEMENT > > In February 2009, two space satellites orbiting at speeds of almost 17,000 > mph collided at a height of 482 miles over Siberia. > > One was an operational U.S. communications satellite, Iridium-33. The > other was a heavier, obsolete Russian military satellite called > Cosmos-2251. For space scientists, the collision was a rude awakening to a > worrisome kind of new math. > > The ultra-high-speed collision turned two space orbiters in a cloud of > debris with 2,300 objects. That made other scientists—climate > scientists—take note, because changes in the upper atmosphere stand to > increase the risk of space collisions. There are currently 21,000 pieces of > trackable space debris, ranging in size from upper stages of old rockets to > dime-sized chunks of metal. > > ADVERTISEMENT > > As Martin Mlynczak, a senior scientist at NASA’s Langley Research Center > in Hampton, Va., recently described it, the buildup of carbon dioxide > emissions aloft is gradually cooling a layer of the upper atmosphere where > satellites frequently orbit. The good news is that the cooling will make > the air there less dense, and that could prolong the life of existing > satellites. The bad news is that it will preserve rapidly accumulating > space junk that might otherwise sink into the lower atmosphere and burn up. > > A study by the European Space Agency (ESA) has described the problem more > bluntly: “A ‘business as usual scenario’ will lead to a progressive, > uncontrolled increase of object numbers in LEO (low earth orbit), with > collisions becoming the primary debris source.” > > The agency proposes to begin to avoid this problem in 2023 by removing > potential pieces of debris from its space vehicles. > > “The [upper] atmosphere is cooling. We know that,” Mlynczak explained in > an interview. “We need to know the density change over the next 50 to 100 > years to keep space habitable for people and satellites.” > > The United States has become highly dependent on space satellites for > communications, Earth observations, military needs, navigation, weather > forecasting and a host of other uses. That’s why satellite launches, > especially those carrying recent clusters of “cubesat” vehicles, roughly > the size of half-gallon milk cartons, are proliferating every year. > > ADVERTISEMENT > > An Indian-made rocket called PSLV-C37 launched 104 of these satellites in > February 2017, spitting them out rapidly from vents in both sides. It was a > world record for India and a milestone for U.S. companies and institutions, > which built 96 of the orbiters (*Climatewire* > <https://www.eenews.net/climatewire/stories/1060072159/>, Jan. 29). > > More destructive collisions that cripple satellites could result in lost > information for science and the military. It would also mean greater costs > for commercial users of satellites, affecting consumers, satellite owners > and companies that insure expensive satellites, Mlynczak explained to a > group of scientists at the National Center for Atmospheric Research in > Boulder, Colo. > > In space, the velocity of even tiny orbiting objects can cause substantial > damage. According to the ESA, the impact of a piece of debris with a > 10-centimeter diameter, roughly the size of a softball, “will most likely > entail a catastrophic disintegration of the target.” > > The ESA reported that in 2016, the solar panel of a major European > satellite, Sentinel-1A, was nearly destroyed, crippling its power supply. > The object that hit it had a 1-centimeter diameter, a dime-sized piece of > space junk. > > In all, according to the ESA, there have been about 5,400 rocket launches > since the space age began in 1957. They have placed about 8,650 satellites > in orbit. Of these, about 4,700 are still in space, but only around 1,800 > are still functioning. Space surveillance networks operated by the United > States, Europe and other nations now estimate there are some 29,000 pieces > of debris that are 10 centimeters in diameter or larger in orbit. Not all > of them are being tracked. > > ADVERTISEMENT > > So far, the ESA estimates there have been more than 500 breakups, > collisions or “anomalous events resulting in fragmentation.” The total > weight of all objects now in orbit amounts to some 8,100 metric tons. With > the increase of launches, currently estimated at 70 to 90 each year, it > says “the probability of catastrophic collisions will also grow in a > progressive manner.” > > NASA and space agencies of some other nations have approved rules that > attempt to limit the projected damage by requiring that new orbiting > vehicles live a maximum of 25 years. After that, they must have orbits or > thrusters that tip them into what are called “graveyard disposal orbits,” > where most of them will burn up. > > So far, according to the ESA, statistics show there have been “poor > results” and that long-term proliferation of space junk is still likely, > even if the rule is observed worldwide. Both NASA and the ESA have done > studies of how they might conduct annual “active debris removal” with space > missions that steer five to 10 of the most dangerous pieces of orbiting > debris into the “graveyard” path. > > The ESA plans to start its “CleanSpace initiative” by removing one of its > orbiting objects in 2023. It estimates that there are risks of a large > piece of space debris failing to burn up completely in the lower > atmosphere, but they are “several orders of magnitude smaller than commonly > accepted risks faced in daily life.” So far, there have been no known human > casualties. > > According to Mlynczak, precisely locating and physically removing orbiting > objects is complicated by solar storms. They can cause variations in the > Earth’s magnetic field and make it more difficult to track objects during > two- or three-day intervals. > > ADVERTISEMENT > > It appears, however, that the Earth is heading into a period where solar > activity is weakening, and that, Mlynczak said, “may give you an > opportunity to do something here.” New satellite systems could help track > orbiting objects and provide better estimates of the long-term density > reductions being caused by more carbon dioxide accumulating in the upper > atmosphere. > > “But it is a technology challenge to develop small, low-cost sensors that > could be routinely orbited over long periods to develop the accurate record > needed to reliably forecast the long-term density changes. This should be > an active area of technology investment and research,” Mlynczak said. > > The most critical measure needed, he said, will be an accurate stream of > data that allows space agencies to project the declining density of the > upper atmosphere, where satellites and debris will be orbiting in the next > 50 to 100 years. That’s one more dimension to the overall costs of rising > CO2 levels. > > *Reprinted from Climatewire with permission from E&E News. E&E provides > daily coverage of essential energy and environmental news at www.eenews.net > <http://www.eenews.net/>.* > > -- > You received this message because you are subscribed to the Google Groups > "Carbon Dioxide Removal" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected] > . > Visit this group at https://groups.google.com/group/CarbonDioxideRemoval. > To view this discussion on the web visit > https://groups.google.com/d/msgid/CarbonDioxideRemoval/CAJ3C-053nyVeY0Opdm2Am2trV2UkCAjwmj2wObPhLu%2BgQm9cLg%40mail.gmail.com > <https://groups.google.com/d/msgid/CarbonDioxideRemoval/CAJ3C-053nyVeY0Opdm2Am2trV2UkCAjwmj2wObPhLu%2BgQm9cLg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
