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STS-47: Spacelab Japan
The 50th flight of the space shuttle took place in September 1992. Endeavour's mission featured the Spacelab-J research module for Japan, as well as the first black female astronaut and the first married couple to fly together in space. The crew narrates the highlights in their post-flight film.

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STS-46: Unreeling the tethered satellite
Shuttle Atlantis' summer 1992 flight provided the chance to test a revolutionary payload -- the Tethered Satellite System. A snag in the tether prevented a small satellite from reeling miles away from the shuttle as planned, the partial deployment showed power generation using the shoelace-size tether could work. The STS-46 mission also released the European Retrievable Carrier spacecraft to begin a year-long stay in orbit. The astronauts narrate highlights from the flight in this movie.

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STS-117 crew bios
Three veterans and three rookies make up the six-man astronaut crew launching aboard space shuttle Atlantis' STS-117 space station assembly mission. Meet the crew members and learn how each became an astronaut in this special biography movie.

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Mars rover flyovers
Images taken by the Mars Reconnaissance Orbiter have been assembled to create these flyover animations of the Columbia Hills where the Spirit rover is exploring and the Opportunity rover at Victoria Crater.

 Spirit | Opportunity

Seas on Titan
NASA's Cassini spacecraft has found evidence for seas, likely filled with liquid methane or ethane, in the high northern latitudes of Saturn's moon Titan. This movie includes animation of the craft's encounters with Titan and an interview with insight into the science.

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Atlas 5 launches STP 1
The United Launch Alliance Atlas 5 rocket with the U.S. military's Space Test Program 1 payload launches Cape Canaveral.

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Atlantis rolls back
Battered by an intense hail storm six days earlier, space shuttle Atlantis retreated off launch pad 39A and returned to the cavernous Vehicle Assembly Building on March 4 to undergo thorough inspections and repairs.

 Video | Time-lapse

STS-112: ISS expansion
Atlantis made a week-long visit to the International Space Station in October 2002 that began the outward expansion of the outpost's truss backbone. Attachment of the 14.5-ton Starboard 1 segment was primary objective of the STS-112 mission. The astronauts tell the story of the flight in this post-flight movie.

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NASA budget hearing
This U.S. Senate space subcommittee hearing to examine NASA's proposed Fiscal Year 2008 budget features testimony from NASA Administrator Mike Griffin on February 28.

 Part 1 | Part 2

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Global 'sunscreen' has likely thinned, NASA scientists say
NASA-GSFC NEWS RELEASE
Posted: March 26, 2007

GREENBELT, Md. - A new NASA study has found that an important counter-balance to the warming of our planet by greenhouse gases - sunlight blocked by dust, pollution and other aerosol particles - appears to have lost ground.

The thinning of Earth's "sunscreen" of aerosols since the early 1990s could have given an extra push to the rise in global surface temperatures. The finding, published today in the journal Science, may lead to an improved understanding of recent climate change. In a related study published this month, scientists found that the opposing forces of global warming and the cooling from aerosol-induced "global dimming" can occur at the same time.

"When more sunlight can get through the atmosphere and warm Earth's surface, you're going to have an effect on climate and temperature," said lead author Michael Mishchenko of NASA's Goddard Institute for Space Studies (GISS), New York. "Knowing what aerosols are doing globally gives us an important missing piece of the big picture of the forces at work on climate."

The study uses the longest uninterrupted satellite record of aerosols in the lower atmosphere, a unique set of global estimates funded by NASA. Scientists at GISS created the Global Aerosol Climatology Project by extracting a clear aerosol signal from satellite measurements originally designed to observe clouds and weather systems that date back to 1978. The resulting data show large, short-lived spikes in global aerosols caused by major volcanic eruptions in 1982 and 1991, but a gradual decline since about 1990. By 2005, global aerosols had dropped as much as 20 percent from the relatively stable level between 1986 and 1991.

The NASA study also sheds light on the puzzling observations by other scientists that the amount of sunlight reaching Earth's surface, which had been steadily declining in recent decades, suddenly started to rebound around 1990. This switch from a "global dimming" trend to a "brightening" trend happened just as global aerosol levels started to decline, Mishchenko said.

While the Science paper does not prove that aerosols are behind the recent dimming and brightening trends -- changes in cloud cover have not been ruled out -- another new research result supports that conclusion In a paper published March 8 in the American Geophysical Union's Geophysical Research Letters, a research team led by Anastasia Romanou of Columbia University's Department of Applied Physics and Mathematics, New York, also showed that the apparently opposing forces of global warming and global dimming can occur at the same time.

The GISS research team conducted the most comprehensive experiment to date using computer simulations of Earth's 20th-century climate to investigate the dimming trend. The combined results from nine state-of-the-art climate models, including three from GISS, showed that due to increasing greenhouse gases and aerosols, the planet warmed at the same time that direct solar radiation reaching the surface decreased. The dimming in the simulations closely matched actual measurements of sunlight declines recorded from the 1960s to 1990.

Further simulations using one of the Goddard climate models revealed that aerosols blocking sunlight or trapping some of the sun's heat high in the atmosphere were the major driver in 20th-century global dimming. "Much of the dimming trend over the Northern Hemisphere stems from these direct aerosol effects," Romanou said. "Aerosols have other effects that contribute to dimming, such as making clouds more reflective and longer-lasting. These effects were found to be almost as important as the direct effects."

The combined effect of global dimming and warming may account for why one of the major impacts of a warmer climate -- the spinning up of the water cycle of evaporation, more cloud formation and more rainfall -- has not yet been observed. "Less sunlight reaching the surface counteracts the effect of warmer air temperatures, so evaporation does not change very much," said Gavin Schmidt of GISS, a co-author of the paper. "Increased aerosols probably slowed the expected change in the hydrological cycle."

Whether the recent decline in global aerosols will continue is an open question. A major complicating factor is that aerosols are not uniformly distributed across the world and come from many different sources, some natural and some produced by humans. While global estimates of total aerosols are improving and being extended with new observations by NASA's latest generation of Earth-observing satellites, finding out whether the recent rise and fall of aerosols is due to human activity or natural changes will have to await the planned launch of NASA's Glory Mission in 2008.

"One of Glory's two instruments, the Aerosol Polarimetry Sensor, will have the unique ability to measure globally the properties of natural and human-made aerosols to unprecedented levels of accuracy," said Mishchenko, who is project scientist on the mission.

John Glenn Mission Patch

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The historic first orbital flight by an American is marked by this commemorative patch for John Glenn and Friendship 7.
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Final Shuttle Mission Patch

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The crew emblem for the final space shuttle mission is available in our store. Get this piece of history!
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Celebrate the shuttle program

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This special commemorative patch marks the retirement of NASA's Space Shuttle Program. Available in our store!
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Anniversary Shuttle Patch

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This embroidered patch commemorates the 30th anniversary of the Space Shuttle Program. The design features the space shuttle Columbia's historic maiden flight of April 12, 1981.
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Mercury anniversary

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Celebrate the 50th anniversary of Alan Shephard's historic Mercury mission with this collectors' item, the official commemorative embroidered patch.
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Fallen Heroes Patch Collection
The official patches from Apollo 1, the shuttle Challenger and Columbia crews are available in the store.
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