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Category Archives: 06. The terrestrial planets: Earth

From an article in the New York Times, August 31, 2016:

Geologists in Greenland have discovered evidence for ancient life in rocks that are 3.7 billion years old.

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Credit: Allen Nutman/NYT

They are thought to be stromatolites, layers of sediment packed together by microbial communities living in shallow water. They are some 220 million years more ancient than the oldest previously known fossils, also stromatolites, from the Pilbara region of Western Australia.

The find, if confirmed, would make these fossils the oldest on Earth and may change scientific understanding of the origins of life.

Link: the full NYT article.

From an article on Sky and Telescope by David Dickinson, originally posted on December 9, 2015.

The Japanese Aerospace Exploration Agency’s (JAXA) Venus Climate Orbitor Akatsuki is finally orbiting Venus – five years later than planned. After a catastrophic main engine failure in 2010 causing the spacecraft to fly past Venus instead of entering its orbit, scientists and engineers have salvaged the mission and put Akatsuki back on track.

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Credit: JAXA

On December 6th 2015, five years to the day of the original blip, four tiny reaction-control thrusters burned for more than 20 minutes to insert the spacecraft into Venusian orbit. Engineers had tested these thrusters to ensure it was possible back in 2011, before putting the spacecraft into hibernation to prolong its life. The first opportunity to execute the manouver came at the beginning of this month, and it proved to be second time lucky for JAXA’s spacecraft.

The six instruments aboard the Akatsuki spacecraft will probe Venus’s atmosphere, measuring its rotation and convection.Researchers also hope to detect evidence for Venusian lightning using a high-speed imager aboard the spacecraft. Viewing across radio, infrared, visible and ultraviolet wavelengths, the payload will also record heat radiated from the Venusian surface and may spot active volcanoes if they exist. A series of radio occultation experiments will also allow researchers to probe the depths of the Venusian atmosphere as the spacecraft makes successive passes behind the planet as seen from Earth.

In addition to the science payload, JAXA also teamed up with the Planetary Society to carry more than 260,000 people’s names and messages printed on aluminium plates aboard the spacecraft.

Whilst the new orbit time is much longer than originally planned, with a closest approach of 400km as opposed to the intended 300km, the JAXA engineers have saved the mission from disaster. Akatsuki, meaning ‘dawn’ in Japanese, will begin to send back its findings in 2016, and as it’s the first time that JAXA have managed to put a spacecraft in orbit around another planet, their wait will hopefully be rewarded.

For more information on the terrestrial planets, see Chapter 6 of The Cosmos.

Link to the original article here.

Credit: Lunar and Planetary Insitute

Credit: Lunar and Planetary Insitute

Planetary Science Nuggets are PowerPoint slides that have been provided to NASA Science Mission Directorate’s Planetary Science Division by members of the scientific community to highlight important science results or mission activities. A subset of these submissions are selected by the Planetary Science Division to be presented to SMD leadership and, potentially, NASA leadership, OSTP and the White House. This collection represents those selected Nuggets.

Link: Planetary Science Nuggets hosted by the Lunar and Planetary Institute.

From a NASA press release, July 20, 2015:

A NASA camera on the Deep Space Climate Observatory (DSCOVR) satellite has returned its first view of the entire sunlit side of Earth from one million miles away.

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Credit: NASA/NOAA/USAF

This color image of Earth was taken by NASA’s Earth Polychromatic Imaging Camera (EPIC), a four megapixel CCD camera and telescope. The image was generated by combining three separate images to create a photographic-quality image. The camera takes a series of 10 images using different narrowband filters — from ultraviolet to near infrared — to produce a variety of science products. The red, green and blue channel images are used in these color images.

The image was taken July 6, 2015, showing North and Central America. The central turquoise areas are shallow seas around the Caribbean islands. This Earth image shows the effects of sunlight scattered by air molecules, giving the image a characteristic bluish tint. The EPIC team is working to remove this atmospheric effect from subsequent images. Once the instrument begins regular data acquisition, EPIC will provide a daily series of Earth images allowing for the first time study of daily variations over the entire globe. These images, available 12 to 36 hours after they are acquired, will be posted to a dedicated web page by September 2015.

The primary objective of DSCOVR, a partnership between NASA, the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Air Force, is to maintain the nation’s real-time solar wind monitoring capabilities, which are critical to the accuracy and lead time of space weather alerts and forecasts from NOAA.

Links: NASA press release, DSCOVR homepage.