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Astrobiologist David Grinspoon believes that scientists should look at our neighboring planets to help understand the perils of global warming. “It seems that both Mars and Venus started out much more like Earth and then changed. They both hold priceless climate information for Earth."

The atmosphere of Venus is much thicker than Earth’s. Nevertheless, current climate models can reproduce its present temperature structure well. Now planetary scientists want to turn the clock back to understand why and how Venus changed from its former Earth-like conditions into the inferno of today.

Climate scientists believe that the planet experienced a runaway greenhouse effect as the Sun gradually heated up. Astronomers believe that the young Sun was dimmer than the present-day Sun by 30 percent. Over the last 4 thousand million years, it has gradually brightened. During this increase, Venus’s surface water evaporated and entered the atmosphere.

“Water vapor is a powerful greenhouse gas and it caused the planet to heat-up even more. This is turn caused more water to evaporate and led to a powerful positive feedback response known as the runaway greenhouse effect,” says Grinspoon.

A week after launching a new orbiter to investigate the upper atmosphere of Mars, NASA is now sending a sounding rocket to probe the atmosphere of Venus. The Mars Atmosphere and Volatile Evolution, or MAVEN, mission launched from Cape Canaveral Air Force Station in Florida on Nov. 18. Now, the Venus Spectral Rocket, VeSpR for short, is scheduled to lift off from White Sands, N.M., on Nov. 25.

"It is appropriate that these launch dates are close together, because both missions will study atmospheric loss," said Kelly Fast, the program scientist for MAVEN and the program officer for Planetary Astronomy at NASA Headquarters in Washington. "VeSpR will peek at Venus from above Earth's absorbing atmosphere, and MAVEN will journey to Mars to do a long-term study."

NASA is launching a sounding rocket to study ultraviolet light being emitted from the atmosphere of 
VeSpR is a two-stage system, combining a Terrier missile – originally built as a surface-to-air missile and later repurposed to support science missions – and a Black Brant model Mk1 sounding rocket with a telescope inside. Integration took place at NASA’s Wallops Flight Facility in Virginia.

The experiments will look at ultraviolet (UV) light that is being emitted from Venus' atmosphere, which can provide information about the history of the planet's water. Measurements like these cannot be done using Earth-based telescopes because our atmosphere absorbs most UV light before it reaches the ground.

The solution is to make UV measurements from beyond Earth's atmosphere. In this case, the sounding rocket will carry the telescope more than 65 miles (110 kilometers) above the surface of Earth; at that altitude, the atmosphere thins out enough to permit UV readings.

"Venus today has a thick atmosphere that contains very little water, but we think the planet started out with an ocean's worth of water," said John T. Clarke of Boston University, the mission's principal investigator.

Scientists are still trying to determine whether water existed on the surface of Venus or only high up the atmosphere, where temperatures were cooler. If the surface temperature stayed below the boiling point of water long enough, rivers might have once flowed on the planet. Venus may have even had ice.

The key to figuring out how much water Venus once had lies in how much hydrogen and deuterium, a heavier version of hydrogen, remain in the atmosphere. Both can combine with oxygen to make water, either in the familiar H2O form or the rarer hydrogen, deuterium and oxygen form, called HDO. (Very small amounts of D2O also form.)

Intense UV light from the sun has broken apart nearly all of the water molecules in Venus' atmosphere. Because the regular hydrogen atoms in the water are lighter, they escape into space more quickly than the heavier deuterium ones. By comparing the amount of deuterium now in the atmosphereto the amount of hydrogen, researchers can estimate how much water disappeared from Venus and how quickly it happened.

Earlier estimates, made from data collected by NASA's 1978 Pioneer Venus spacecraft and other observations, indicated Venus could have had enough ancient water to cover the whole globe with 23 feet (7 meters) of liquid. But it turns out that the amounts of hydrogen and deuterium can vary at different heights in Venus' atmosphere, which could change the calculations. To help resolve the uncertainty, VeSpR will make measurements specifically in the upper atmosphere.

The VeSpR instrument will observe Venus for 8 minutes, with data being transmitted in real time, before the payload returns on a parachute safely to Earth. Later, the payload will be retrieved so that the instrument can be used for future experiments.

Clarke and his team will combine these measurements with observations of Venus they made recently with NASA's Hubble Space Telescope. The group is also collaborating with Jean-Loup Bertaux of France's Centre National de la Recherche Scientifique to study the planet using the UV instrument on the European Space Agency's Venus Express spacecraft.

VeSpR was built with funding from NASA's Planetary Astronomy program. The NASA sounding rocket program is managed for the agency at NASA’s Wallops Flight Facility. MAVEN's principal investigator is based at the University of Colorado Laboratory for Atmospheric and Space Physics in Boulder. NASA's Goddard Space Flight Center in Greenbelt, Md., manages MAVEN. Lockheed Martin built the MAVEN spacecraft and is responsible for mission operations.

The Daily Galaxy via Elizabeth Zubritsky, NASA's Goddard Space Flight Center

Image credit: ESA


Venus use to be exactly earth-like over half a billion years ago! Its catastrophe was much deeper than merely 'global warming'!

"NASA is launching a sounding rocket to study ultraviolet light being emitted from the atmosphere of
VeSpR is a two-stage system..."

Might want to fix that.

First, we do not know Venus had an Earth-like atmosphere, that's a presumption. Second, Venus is much closer to the sun. Third, the sun has increased its heat output significantly over the last 4B.

Venus is not a synonym for Earth other than it is a rocky planet.

If Venus was where Mars is and Mars where Venus then as the sun warms more perhaps Venus could have been the "new lands" to settle with a few atmospheric "tweeks".

Venus and Mars could have been full of life like Earth is now. But both planets turned into dead onces. Mars into desert, Venus into hell.
I am sure if we send robots there to dig in many different places, we could find stuff like dinosaurs in rocks. Not millions, but billions of years covered the dead so this stuff is not visible now. We've sent Curiosity to Mars and it rides on the surface. We have assumptions about if life was there or not based on what is on the very surface of it. What a nonsense. Hundres of milions of years of time, or billions of years simply covered anything what was interesting there, with a thick surface of sand/rock. This is so obvious. If like evolved on Earth in this solar system, why it would not evolve on both other planets? I assume the life was there as well. Only time has hidden traces of it!

I would love to know what heat is actually coming from the interior of the planet. The mantle of the planet has not hardened.

"Extensive Lava Flows

Lava flows on Venus are thought to be composed of rocks that are similar to the basalts found on earth. Many of the lava flows on Venus have lengths of several hundred kilometers.

Volcanic activity on Venus can not be detected from Earth but enhanced radar imaging from the Magellan spacecraft suggest that volcanic activity on Venus still occurs"

But how much


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