Study on Ozone Aims at Rockets : Environment: El Segundo center will measure the effect of launches on Earth’s fragile protective shield.
As U.S. space officials face intensifying environmental concerns about space missions, an Air Force-funded research center in El Segundo this fall will begin studying 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 overexposure 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 launches by the Nationa Aeronautics and Space Administration and by the military.
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 want to avoid interruptions in 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 Aerospace Corp.’s space and environment technology division.
Those worries are shared by NASA, which has already done testing and computer modeling of launch-related ozone depletion. The space agency plans to research the problem further.
Air Force and NASA officials say the ozone research is likely to influence the types of fuels used in the National Launch System, a new generation of rockets scheduled to come into use 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 rockets such as the boosters that help power the space shuttle and the Air Force Titan 4. Solid fuel is considered more destructive to ozone than liquid fuel because a byproduct of its combustion is hydrogen chloride. Like chlorofluorocarbons, 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--approximately the current launch rate--ozone reduction would amount on average to less than 0.1%, far less than that caused by manufacturing emissions, according to Charles Jackman, an atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md.
But critics say that estimate is shortsightedly low and point out that each shuttle launch injects more chlorine into the stratosphere than an average individual industrial plant does in a year.
That alone, environmentalists say, justifies redesigning or abandoning future solid-fuel rockets.
Military and NASA officials are preparing for increasing environmental regulations on space shots.
In Hawaii, a federal judge in May ordered the Army to delay a series of “Star Wars”-related missile firings from the island of Kauai until it gauges the project’s atmospheric effects.
“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.
The Environmental Protection Agency “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 that will cost 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 with chlorine, may influence ozone depletion.
Air Force and Aerospace Corp. officials say the next step--the cost 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.
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.
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.”
