Advertisement

If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.

ENJOY UNLIMITED ACCES TO C&EN

Physical Chemistry

Getting Close To Venus

Venus Express spacecraft tracks escaping ions, lightning on Earth's twin

by Elizabeth K. Wilson
December 3, 2007 | A version of this story appeared in Volume 85, Issue 49

Oxygen Glow
[+]Enlarge
Credit: R. Hueso, Grupo de Ciencias Planetarias, Univ. del País Vasco, Spain
This false-color image, taken by the European Space Agency’s Venus Express spacecraft, shows patterns of oxygen atoms released by photodissociation of CO2 in Venus’ upper atmosphere during the daytime (left). The atmospheric currents shuttle the atoms to the night side of the planet, where they combine to form O2, generating an infrared airglow (right).
Credit: R. Hueso, Grupo de Ciencias Planetarias, Univ. del País Vasco, Spain
This false-color image, taken by the European Space Agency’s Venus Express spacecraft, shows patterns of oxygen atoms released by photodissociation of CO2 in Venus’ upper atmosphere during the daytime (left). The atmospheric currents shuttle the atoms to the night side of the planet, where they combine to form O2, generating an infrared airglow (right).

This discovery is just one in a slew of results from the European Space Agency’s Venus Express spacecraft that were announced at a press conference in Paris on Nov. 28. The results are also published in nine papers in the same issue of Nature (2007, 450, 629, 633, 637, 641, 646, 650, 654, 657, and 661).

With similar mass and density and about the same amount of CO2 as Earth, Venus is in many ways Earth’s twin. But whereas Earth’s CO2 is sequestered in its crust, most of Venus’ CO2 is in the atmosphere. And whereas Earth is covered in oceans, Venus is dry as a bone—an uninhabitable place with surface temperatures of about 450°C and a wild, turbulent atmosphere with pressure 100 times that of Earth. Scientists believe the two planets started out similarly but aren’t sure why they ended up being so different.

Numerous spacecraft have explored Venus, starting with the U.S.’s Mariner 2 in 1962. The last mission dedicated to the study of Venus was NASA’s Magellan, which ended in 1994. Venus Express was launched two years ago, and its suite of instruments has been mapping the planet in unprecedented detail since last April.

“We’ve come back to a new era in Venus research,” Håkan Svedhem, a Venus Express Project scientist, said at the news conference.

Venus Express has sent back detailed measurements of H+, O+, and He+ escaping Venus’ atmosphere. O+ is escaping at half the rate of H+, suggesting that this is a way Venus may be losing water. The planet may have lost oceans’ worth of water over billions of years.

The spacecraft also has traced the transport of oxygen and other species around the planet. On the day side of Venus, the dissociation of CO2 produces atomic oxygen; the turbulent atmospheric currents then shuttle oxygen atoms to the planet’s night side, where they recombine to form O2 and generate an infrared glow.

In addition, Venus Express sent back the first confirmation of lightning on Venus. Lightning, which produces ozone and nitrogen oxides on Earth, undoubtedly also affects the chemistry of the Venutian atmosphere, a fact that will have to be included in future atmospheric models of the planet, noted Venus Express Interdisciplinary Scientist David Grinspoon.

“The next pictures [of Venus’ atmosphere] in textbooks will have to have a lightning flash,” Grinspoon said.

This false-color animation shows the movement of the atmosphere over the southern hemisphere of Venus, over a period of an Earth week. The images, taken by the European Space Agency's Venus Express spacecraft, show blue areas as coldest; yellow, warmest.

Article:

This article has been sent to the following recipient:

0 /1 FREE ARTICLES LEFT THIS MONTH Remaining
Chemistry matters. Join us to get the news you need.