science&news: February 2015

Tuesday, 17 February 2015

NASA to send submarine to Saturn’s moon Titan

By: PTI | Washington | February 17, 2015 7:08 pm

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US Space agency NASA's single-tonne concept robot submarine is equipped with a seafloor camera and sampling system. (Reuters)

NASA is planning to send a nuclear-powered submarine to explore one of the methane seas located on Saturn’s moon Titan.

The single-tonne concept robot submarine is equipped with a seafloor camera and sampling system.

The submarine could fit into a space plane such as Boeing’s X-37, which was recently used for a classified Air Force mission.

The plane could land on Kraken Mare, the largest known body of liquid on Titan that consists mostly of liquid methane, or possibly drop the submarine using a parachute, ‘ibtimes.com’ reported.

“The vehicle would use conventional propulsors to yaw around, using a sun sensor to determine the initial azimuth to Earth and begin communication using a terrestrial radio as a more precise reference,” NASA said.

NASA hopes to use the submarine to explore the chemistry of Titan’s seafloor and sea composition, as well as study its tides, weather, shoreline, islands and search for any type of life.

The submarine concept was showcased by NASA Glenn’s COMPASS Team and researchers from Applied Research Lab at the NASA Innovative Advanced Concepts (NIAC) Symposium in Florida.

The concept of the submarine is still in its very early stages, but the team expects that it may be up and running by 2047.

“Measurement of the trace organic components of the sea, which perhaps may exhibit prebiotic chemical evolution, will be an important objective, and a benthic sampler (a robotic grabber to sample sediment) would acquire and analyse sediment from the seabed,” the US space agency explained.

These measurements, and seafloor morphology via sidescan sonar, may shed light on the historical cycles of filling and drying of Titan’s seas.

Models suggest Titan’s active hydrological cycle may cause the north part of Kraken to be ‘fresher’ (more methane-rich) than the south, and the submarine’s long traverse will explore these composition variations.

http://www.financialexpress.com/article/lifestyle/science/nasa-to-send-submarine-to-saturns-moon-titan/44138/

Mysterious giant clouds spotted on Mars

Feb 17, 2015, 04.59 PM IST

On two separate occasions in March and April 2012, amateur astronomers reported definite plume-like features developing on the planet.

LONDON: Mysterious cloud-like plumes seen reaching high above the surface of Mars have puzzled scientists studying the atmosphere of the Red Planet.

On two separate occasions in March and April 2012, amateur astronomers reported definite plume-like features developing on the planet.

The plumes were seen rising to altitudes of over 250km above the same region of Mars on both occasions. By comparison, similar features seen in the past have not exceeded 100km.

"At about 250km, the division between the atmosphere and outer space is very thin, so the reported plumes are extremely unexpected," said Agustin Sanchez-Lavega of the Universidad del Pais Vasco in Spain, lead author of the paper published in the journal Nature.

The features developed in less than 10 hours, covering an area of up to 1000 x 500 km, and remained visible for around 10 days, changing their structure from day to day.
None of the spacecraft orbiting Mars saw the features because of their viewing geometries and illumination conditions at the time, researchers said.

However, checking archived Hubble Space Telescope images taken between 1995 and 1999 and of databases of amateur images spanning 2001 to 2014 revealed occasional clouds at the limb of Mars, albeit usually only up to 100km in altitude.

But one set of Hubble images from May 17, 1997 revealed an abnormally high plume, similar to that spotted by the amateur astronomers in 2012.

Scientists are now working on determining the nature and cause of the plumes by using the Hubble data in combination with the images taken by amateurs.

"One idea we've discussed is that the features are caused by a reflective cloud of water-ice, carbon dioxide-ice or dust particles, but this would require exceptional deviations from standard atmospheric circulation models to explain cloud formations at such high altitudes," said Agustin.

"Another idea is that they are related to an auroral emission, and indeed auroras have been previously observed at these locations, linked to a known region on the surface where there is a large anomaly in the crustal magnetic field," added Antonio Garcia Munoz, a research fellow at ESA's ESTEC and co-author of the study.

READ ALSO: Kerala girl a step away from ticket to Mars
3 Indians in 100 shortlisted for one way trip to Mars

http://timesofindia.indiatimes.com/Home/Science/Mysterious-giant-clouds-spotted-on-Mars/articleshow/46274950.cms

Life on Earth May Have Begun 1 Billion Years Earlier Than Thought, Scientists Say

Feb 17, 2015, 10:02 AM ET

By ALYSSA NEWCOMB

PHOTO: Earth is pictured in this stock photo.

The earliest life forms may have blossomed on Earth 1 billion years earlier than previously thought.

Working together, scientists at the University of Washington and the University of Johannesburg in South Africa found evidence that life may have thrived on Earth 3.2 billion years ago, upending the belief that Earth's atmosphere at the time was uninhabitable.

The study is based on an analysis of 52 rock samples collected in South Africa and northwestern Australia and range in age from 2.75 to 3.2 billion years old.

Roger Buick, a University of Washington professor and co-author of the article that was published Monday in the journal Nature, said the rock samples his team analyzed showed that there was plentiful nitrogen 3.2 billion years ago to sustain the most basic life forms, including bacteria, viruses and other organisms.

While life can exist without oxygen, nitrogen is an essential building block for genes.

"People always had the idea that the really ancient biosphere was just tenuously clinging on to this inhospitable planet, and it wasn't until the emergence of nitrogen fixation that suddenly the biosphere become large and robust and diverse," Buick told UW Today.

Rosetta Space Probe Takes Sharp, Close-up Images of Comet

Titan: How NASA Got the Clearest Photo Ever of Saturn's Moon

Astronomers Discover Ancient Solar System With 5 Earth-Like Planets

http://abcnews.go.com/Technology/life-earth-begun-billion-years-earlier-thought-scientists/story?id=29017106

Saturday, 7 February 2015

Einstein's Theory of General Relativity

by Nola Taylor Redd, SPACE.com Contributor | September 18, 2012 06:52pm ET

Theory of General Relativity

Einstein's theory of general relativity predicted that the space-time around Earth would be not only warped but also twisted by the planet's rotation. Gravity Probe B showed this to be correct.

In 1905, Albert Einstein determined that the laws of physics are the same for all non-accelerating observers, and that the speed of light in a vacuum was independent of the motion of all observers. This was the theory of special relativity. It introduced a new framework for all of physics and proposed new concepts of space and time.

Einstein then spent ten years trying to include acceleration in the theory and published his theory of general relativity in 1915. In it, he determined that massive objects cause a distortion in space-time, which is felt as gravity.

The tug of gravity

Two objects exert a force of attraction on one another known as "gravity." Even as the center of the Earth is pulling you toward it (keeping you firmly lodged on the ground), your center of mass is pulling back at the Earth, albeit with much less force. Sir Isaac Newton quantified the gravity between two objects when he formulated his three laws of motion. Yet Newton's laws assume that gravity is an innate force of an object that can act over a distance.

Albert Einstein, in his theory of special relativity, determined that the laws of physics are the same for all non-accelerating observers, and he showed that the speed of light within a vacuum is the same no matter the speed at which an observer travels. As a result, he found that space and time were interwoven into a single continuum known as space-time. Events that occur at the same time for one observer could occur at different times for another.

As he worked out the equations for his general theory of relativity, Einstein realized that massive objects caused a distortion in space-time. Imagine setting a large body in the center of a trampoline. The body would press down into the fabric, causing it to dimple. A marble rolled around the edge would spiral inward toward the body, pulled in much the same way that the gravity of a planet pulls at rocks in space.

Experimental evidence

Although instruments can neither see nor measure space-time, several of the phenomena predicted by its warping have been confirmed.

Einstein's Cross is an example of gravitational lensing.
Credit: NASA and European Space Agency (ESA)

Gravitational lensing: Light around a massive object, such as a black hole, is bent, causing it to act as a lens for the things that lay behind it. Astronomers routinely use this method to study stars and galaxies behind massive objects.

Einstein's Cross, a quasar in the Pegasus constellation, is an excellent example of gravitational lensing. The quasar is about 8 billion light-years from Earth, and sits behind a galaxy that is 400 million light-years away. Four images of the quasar appear around the galaxy because the intense gravity of the galaxy bends the light coming from the quasar.

Changes in the orbit of Mercury: The orbit of Mercury is shifting very gradually over time, due to the curvature of space-time around the massive sun. In a few billion years, it could even collide with the Earth.

Frame-dragging of space-time around rotating bodies: The spin of a heavy object, such as Earth, should twist and distort the space-time around it. In 2004, NASA launched the Gravity Probe B. The precisely calibrated satellite caused the axes of gyroscopes inside to drift very slightly over time, a result that coincided with Einstein's theory.

Gravitational redshift: The electromagnetic radiation of an object is stretched out slightly inside a gravitational field. Think of the sound waves that emanate from a siren on an emergency vehicle; as the vehicle moves toward an observer, sound waves are compressed, but as it moves away, they are stretched out, or redshifted. Known as the Doppler Effect, the same phenomena occurs with waves of light at all frequencies. In 1959, two physicists, Robert Pound and Glen Rebka, shot gamma rays of radioactive iron up the side of a tower at Harvard University and found them to be minutely less than their natural frequency due to distortions caused by gravity.

Gravitational waves: Violent events, such as the collision of two black holes, are thought to be able to create ripples in space-time known as gravitational waves. The Laser Interferometer Gravitational Wave Observatory is presently searching for the first signs of these tell-tale indicators.

— Nola Taylor Redd, SPACE.com Contributor