ON-VenusVortex

Life Zone on Venus Possible
By Leonard David

TEMPE, ARIZONA Microbes may be riding high in the atmosphere of Earths sister planet, Venus.
A research team is proposing that a future mission to that cloud-covered world could scoop up the living proof,
then transport the specimens for detailed inspection onboard the International Space Station.
The speculative work was highlighted during the NASA Astrobiology Institute General Meeting 2003, being held
here February 10-12. Upwards of 600 scientists from around the globe are presenting new findings in
understanding the evolution of life on Earth and elsewhere in the Universe.

Atmospheric niche

Both ground-based instruments and spacecraft that have surveyed Venus shore up the prospect that the lower
cloud deck of the Venusian atmosphere is a plausible habitat for microbial life.
"Our assertion that microbial life may exist in the Venusian atmosphere is based on the assumption that microbial
life originated in an early Venusian ocean, or was brought in by meteorites from Earth or Mars. Life then adapted
to the atmospheric niche when Venus lost its oceans," reported Dirk Schulze-Makuch, of the Department of
Geological Sciences at the University of Texas at El Paso.
These ideas are not free of problems, Schulze-Makuch told SPACE.com.
First theres the overall viability of an atmosphere as a habitat. Also, theres need for enough time for microbial life
to adapt to the atmospheric niche from an oceanic-type of habitat. Toss in a scarcity of water and high doses of
ultraviolet radiation, these too make it tough sledding for life finding a foothold in the clouds of Venus.

Blissful Biozone

To bolster the case for life on Venus, one needs to first look at Earths own atmosphere, Schulze-Makuch said. "Its
not a point of discussionthere are microbes in the Earths atmosphere that independently grow and reproduce.
Actually, the conditions in the Venusian atmosphere would be much better [for microbes] than for Earths
atmosphere," he said.
On Venus, clouds are at 31 miles (50 kilometers) altitude. Thats perfect for a "biozone" a comfortable home for
microbes that is relatively benign. Below that height things are too hot, and any higher theres too much ultraviolet
radiation and zapping from cosmic rays.

Survival strategies

Schulze-Makuch said that he and his research colleagues contend that microbes floating above Venus have
adopted one or more survival strategies.
One way is use of sulfur compounds. The microbes could wrap themselves in a thin coat of those compounds, thus
screening out ultraviolet radiation but allowing photosynthesis to occur. That shell also thwarts sulfuric acid
present in the clouds of Venus.
Next steps in furthering the Venus life idea are already moving forward. Not only is lab work underway, plans are
afoot to use the Hubble Space Telescope to better characterize the clouds of Venus.

Collectibles

Ultimately, Schulze-Makuch said, a sample collection mission to Venus is needed. A top candidate in his mind is for
a rocket-carrying balloon to first snag an atmospheric sample, then hurl the specimen up to a Venus orbiting
mother ship. That craft then transfers the collectibles over to the International Space Station (ISS).

Scientists onboard the ISS would "crack" the captured particles for detailed, internal inspection.

"Nobody will ever believe theres life on Venus until everybody sees it under the microscopeits moving and waving
back," Schulze-Makuch said.