Rocket Launches May Need Regulation to Prevent Ozone Depletion
Delta rocket launches NASA’s Mars Phoenix Lander mission from Cape
Kennedy in 2007.
Image courtesy NASA.
University of Colorado March 31,
The global market
for rocket launches may require more stringent regulation in order to prevent
significant damage to Earth’s stratospheric ozone layer in the decades to come,
according to a new study by researchers in California and Colorado.
Future ozone losses from
unregulated rocket launches will eventually exceed ozone losses due to
chlorofluorocarbons, or CFCs, which stimulated the 1987 Montreal Protocol
banning ozone-depleting chemicals, said Martin Ross, chief study author from The
Aerospace Corporation in Los Angeles. The study, which includes the University
of Colorado at Boulder and Embry-Riddle Aeronautical University, provides a
market analysis for estimating future ozone layer depletion based on the
expected growth of the space industry and known impacts of rocket launches.
“As the rocket launch market
grows, so will ozone-destroying rocket emissions,” said Professor Darin Toohey
of CU-Boulder’s atmospheric and oceanic sciences department. “If left
unregulated, rocket launches by the year 2050 could result in more ozone
destruction than was ever realized by CFCs.”
A paper on the subject by Ross
and Manfred Peinemann of The Aerospace Corporation, CU-Boulder’s Toohey and
Embry-Riddle Aeronautical University’s Patrick Ross appeared online in March in
the journal Astropolitics.
Since some proposed space efforts
would require frequent launches of large rockets over extended periods, the new
study was designed to bring attention to the issue in hopes of sparking
additional research, said Ross. “In the policy world uncertainty often leads to
unnecessary regulation,” he said. “We are suggesting this could be avoided with
a more robust understanding of how rockets affect the ozone layer.”
Current global rocket launches
deplete the ozone layer by no more than a few hundredths of 1 percent annually,
said Toohey. But as the space industry grows and other ozone-depleting chemicals
decline in the Earth’s stratosphere, the issue of ozone depletion from rocket
launches is expected to move to the forefront.
Today, just a handful of NASA
space shuttle launches release more ozone-depleting substances in the
stratosphere than the entire annual use of CFC-based medical inhalers used to
treat asthma and other diseases in the United States and which are now banned,
said Toohey. “The Montreal Protocol has left out the space industry, which could
have been included.”
Highly reactive trace-gas
molecules known as radicals dominate stratospheric ozone destruction, and a
single radical in the stratosphere can destroy up to 10,000 ozone molecules
before being deactivated and removed from the stratosphere. Microscopic
particles, including soot and aluminum oxide particles emitted by rocket
engines, provide chemically active surface areas that increase the rate such
radicals “leak” from their reservoirs and contribute to ozone destruction, said
In addition, every type of rocket
engine causes some ozone loss, and rocket combustion products are the only human
sources of ozone-destroying compounds injected directly into the middle and
upper stratosphere where the ozone layer resides, he said.
Although U.S. science agencies
spent millions of dollars to assess the ozone loss potential from a hypothetical
fleet of 500 supersonic aircraft — a fleet that never materialized — much less
research has been done to understand the potential range of effects the existing
global fleet of rockets might have on the ozone layer, said Ross.
Since 1987 CFCs have been banned
from use in aerosol cans, freezer refrigerants and air conditioners. Many
scientists expect the stratospheric ozone layer — which absorbs more than 90
percent of harmful ultraviolet radiation that can harm humans and ecosystems —
to return to levels that existed prior to the use of ozone-depleting chemicals
by the year 2040.
Rockets around the world use a
variety of propellants, including solids, liquids and hybrids. Ross said while
little is currently known about how they compare to each other with respect to
the ozone loss they cause, new studies are needed to provide the parameters
required to guide possible regulation of both commercial and government rocket
launches in the future.
“Twenty years may seem like a
long way off, but space system development often takes a decade or longer and
involves large capital investments,” said Ross. “We want to reduce the risk that
unpredictable and more strict ozone regulations would be a hindrance to space
access by measuring and modeling exactly how different rocket types affect the
The research team is optimistic
that a solution to the problem exists. “We have the resources, we have the
expertise, and we now have the regulatory history to address this issue in a
very powerful way,” said Toohey. “I am optimistic that we are going to solve
this problem, but we are not going to solve it by doing nothing.”
The research was funded by the
National Science Foundation, NASA and The Aerospace Corporation. For more
information on CU-Boulder’s atmospheric and oceanic sciences department visit
atoc.colorado.edu/index.php. For more information on The Aerospace
Corporation visit www.aero.org/.