Is Space Age Offing the Ozone? : Environment: An El Segundo research center will study whether rocket launches are helping destroy the Earth’s ozone layer.
As U.S. space officials confront a constellation of budgetary and technical troubles, environmental concerns about space missions are also emerging. This fall, an Air Force-funded research center in El Segundo will begin studying one of the most prominent--the effect of rocket launches on the earth’s fragile ozone shield.
The Aerospace Corp. plans to investigate the role of solid rocket fuel combustion in the destruction of the ozone, which protects the earth from over-exposure to the sun’s ultraviolet rays. Experts say excessive ultraviolet radiation can cause skin cancer in humans and various environmental problems, including reduced photosynthesis in plants.
Scientists have been aware for years that rockets can affect ozone. But the Aerospace Corp. study comes amid concern that increasing political and regulatory pressure to protect the ozone layer could soon limit NASA and military lift-offs.
Already, a federal judge in Hawaii has delayed a series of Army missile launches in the Pacific, in part to determine whether the tests conflict with a state ozone protection statute.
With the Bush Administration advocating such multibillion-dollar projects as a manned mission to Mars, an orbiting space station and Star Wars weaponry, space officials say they would not relish interruptions in future launch schedules.
“What the Air Force doesn’t want is to be unable to launch satellites because of environmental concerns,” said Andrew Christensen, director of The Aerospace Corp.’s space and environment technology division.
Those worries are shared by NASA, which has already performed tests and computer modeling of launch-related ozone depletion. The space agency plans to research the problem further.
“This will help us make informed decisions,” said Rebecca McCaleb, environmental chief at NASA’s Marshall Space Flight Center in Huntsville, Ala. “We don’t want to eliminate (launch) systems that are within the Earth’s tolerance, but it’s also important that we don’t continue to pursue systems that have impacts that may be unacceptable over the long run.”
Air Force and NASA officials say the ozone research will likely influence the types of fuels that will be used in the National Launch System, a new generation of rockets scheduled to come into use sometime after the year 2000.
But environmentalists are concerned about two rockets that are being considered for development even sooner than that--the Air Force’s Advanced Titan and a new booster for NASA’s space shuttle.
“If (the research) is merely used to redesign launch vehicles five to 10 years down the road, that’s not good enough,” said Lenny Siegel, chief researcher on military toxics for the National Toxics Campaign Fund, an environmental group based in Boston. “A whole lot of damage will be done if the lessons we’re learning now aren’t applied now.”
Most man-made ozone depletion is believed to be caused by industrial releases of gases called chlorofluorocarbons, but all contributors to the problem--rocket launches included--have attracted growing attention since 1985. That year, British scientists discovered a hole in the ozone layer above Antarctica, stirring fear that the depletion problem might be worse than previously thought.
Concern about rocket launches centers on solid fuel-powered rockets such as the boosters that help power the space shuttle and the Air Force Titan IV. Solid fuel is considered more destructive to ozone than liquid fuel because a byproduct of its combustion is hydrogen chloride. Like chlorofluorocarbons, the hydrogen chloride releases chlorine, a key chemical villain in the process of ozone depletion.
NASA computer models suggest that overall, ozone depletion from Titan and shuttle launches is small. If nine shuttles and six Titans are launched annually for 20 years--about the current launch rate--ozone reduction would amount on average to less than 0.1%, according to Charles Jackman, an atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md.
Another way to look at it, Jackman says, is to compare the amounts of chlorine sent into the stratosphere each year as a result of rocket launches and factory emissions. Rocket launches are estimated to account for less than 800 tons, he said, while factories account for more than 300,000.
But critics cite a 1974 experiment indicating that upper atmosphere ozone depletion near rocket exhaust trails may be acute. The experiment detected ozone depletion of more than 40% in the exhaust trail of a Titan rocket.
Critics also point out that each shuttle launch--which injects about 75 tons of chlorine into the stratosphere--does more to destroy ozone than the annual chlorofluorocarbon emissions of most individual industrial plants, a calculation Jackman accepts.
That alone, environmentalists say, justifies redesigning or abandoning future solid-fuel rockets. Said Siegel: “If you say this source is too small to worry about, then you can say every source is too small.”
Military and NASA officials say they are becoming increasingly cognizant of such questions. They believe the country’s space projects might soon become subject to tightened environmental regulation. Recent developments suggest they might be right.
In Hawaii, a federal judge in May ordered the Army to delay a series of missile firings from the island of Kauai until it fully gauges the project’s atmospheric effects. Among the questions the Army must address is whether the firings, to test a Star Wars-related missile tracking system, contravene a state law limiting the release of ozone-depleting chemicals.
The ruling was prompted by legal challenges by the state of Hawaii and the Sierra Club Legal Defense Fund.
“This is the first time that a launch schedule has been impacted by public concerns over atmospheric effects of the launches,” said Steven Aftergood, a research analyst with the Federation of American Scientists based in Washington.
Meanwhile, ozone depletion is coming under increased regulatory scrutiny at the national and international levels.
Members of the Montreal Protocol on Substances that Deplete the Ozone Layer, a 56-nation conference developing international ozone protection policies, have ordered their scientific assessment panel to prepare a report on launch-related ozone depletion by next year.
In Washington, amendments made last year to the federal Clean Air Act confer broad authority on the U.S. Environmental Protection Agency to address ozone depletion, and space officials say rocket launches may eventually be affected.
“The EPA has yet to develop precisely what their regulations will be, but we know it’s coming,” said John Edwards, an Air Force environmental official. “And we know there’s global concern about the ozone layer. So we’re going to check, so we know what our contribution is, and do everything we can to minimize it.”
The Aerospace Corp. is scheduled to begin its ozone research this fall in El Segundo with the first in a yearlong series of lab tests involving two to three scientists at a cost of about $100,000. Ozone gas will be exposed not only to chlorine, but also to aluminum compounds--another byproduct of solid rocket fuel combustion.
Valerie Lang, the scientist who will oversee the lab work, says previous research has not explored how aluminum compounds, acting alone or in conjunction with chlorine, may influence ozone depletion.
Air Force and Aerospace Corp. officials say the next step--the cost and duration of which has yet to be determined--will be to use ground-based sensing devices to measure ozone levels during rocket launches at Vandenberg Air Force Base.
The officials say the experiments will concentrate on ozone depletion close to the rocket plume. Eventually, they say, the ozone project may involve the use of military satellites.
“We hope to build on the expertise that has grown out of defense applications of space-based observation techniques,” said David Gorney, director of The Aerospace Corp’s atmospheric and ionospheric sciences department. “When you have a different community of scientists work on a problem, there’s value in that.”
Proponents of prompt action on the ozone problem say they hope the findings will influence U.S. space policy. Said Aftergood: “It’s important that the launch industry be part of the solution, not part of the problem.”
