Astronomy Now Home
Home Magazine Resources Store

On Sale Now!



The October 2014 issue of Astronomy Now is on sale! Order direct from our store (free 1st class post & to UK addresses). Astronomy Now is the only astronomy magazine specially designed to be read on tablets and phones. Download the app from Google Play Store or the Apple App Store.



Top Stories



Earthshine used to test life detection method
...By imagining the Earth as an exoplanet, scientists observing our planet's reflected light on the Moon with ESO's Very Large Telescope have demonstrated a way to detect life on other worlds...
  READ MORE

Solid buckyballs discovered in space
...Astronomers using NASA’s Spitzer Space Telescope have detected a particular type of molecule, given the nickname “buckyball”, in a solid form for the first time...
  READ MORE

Steamy water-world gets the Hubble treatment
...Hubble Space Telescope observations of a 7 Earth-mass planet find an unusual water-rich world swathed in a thick, steamy atmosphere...
  READ MORE








Study suggests water was a global occurrence on Mars
BY STEPHEN CLARK
SPACEFLIGHT NOW
Posted: 23 June 2010


Bookmark and Share

Two probes circling the Red Planet have discovered evidence that water was once present in the northern hemisphere of Mars, a sign the planet's entire surface may have been habitable billions of years ago.


Lyot crater is one of nine sites in the Martian northern hemisphere with exposed clay-like minerals that formed in ancient watery environments. This image shows the locations of the minerals and the areas scouted by Mars Express' OMEGA instrument and MRO's CRISM spectrometer. Credit: NASA/ESA/JPL-Caltech/JHU-APL/IAS
 
The European Space Agency's Mars Express mission and NASA's Mars Reconnaissance Orbiter teamed up to make the discovery, which is the first definitive proof that all of Mars was affected by water, not just the southern hemisphere.

NASA announced the findings Thursday, and a report describing the research is published in the journal Science this week.

"We can now say that the planet was altered on a global scale by liquid water about four billion years ago," said John Carter of the University of Paris, the report's lead author.

According to NASA, spectrometers on Mars Express and MRO have mapped clay minerals at thousands of sites in the planet's southern highlands, confirming surface observations from the agency's rovers that Mars once hosted a wet, and perhaps habitable, environment.

But younger volcanic rock paved over the ancient surface material in the northern hemisphere, hiding the tell-tale clay minerals that must have formed in a watery environment.

The OMEGA spectrometer on Mars Express first detected the chemical signature of clays and phyllosilicates, both indicators that water once existed in those locations. The clays were exposed by more recent impact craters carved by asteroids and comets.

Scientists followed up on OMEGA's observations with the CRISM instrument on MRO, which verified the discovery with its high-resolution imager.


Artist's concept of MRO. Credit: NASA/JPL-Caltech
 
"We needed the better spatial resolution to confirm the identifications," Carter said. "The two instruments have different strengths, so there is a great advantage to using both."

CRISM studied 91 craters in the northern lowlands and found clays and phyllosilicates in at least nine of the sites.

The clay markers also give clues on the sequence of geologic events that shaped Mars, including a massive collision with a large object that slammed into the planet's northern hemisphere. The impact smashed down the northern hemisphere, leaving the region with a lower average elevation than southern Mars.

Researchers say evidence of water in the northern lowlands implies the planet-crushing impact occurred well before the end of the wet epoch in Martian history, narrowing the window of time in which Mars may have been habitable.

"That large impact would have eliminated any evidence for the surface environment in the north that preceded the impact," said Scott Murchie, CRISM principal investigator from the Johns Hopkins University Applied Physics Laboratory. "It must have happened well before the end of the wet period."

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.
 GET YOUR COPY

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
 GET YOUR COPY

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
 GET YOUR COPY


HOME | NEWS ARCHIVE | MAGAZINE | SOLAR SYSTEM | SKY CHART | RESOURCES | STORE | SPACEFLIGHT NOW

© 2014 Pole Star Publications Ltd.