Land and oceans
White roofs could cool cities: study
Enzyme crystal helps crack HIV puzzle
Sugar sweetens decision making
Twilight zone secrets revealed
Astronomers spot asteroid collision
Algae master quantum mechanics
Protein 'ushers' key to beating malaria
Researchers spin artificial bee silk
New view of Pluto increases mystery
Cell's power packs came from within
Antarctic snow linked to WA dry
Termites inspire hydrophobic materials
Study shows why it's scary to lose money
Soil impact underestimated: climate study
Lack of oxygen forced fish's first breath
Harder Sudoku puzzles on the way?
Weed genes could help feed the world
Logging makes forests more flammable: study
Food crisis looms warn scientists
Tiny sensors track 'lost' objects
'Climategate' university orders review
'Plumbing' key to flowering success
New twist on solar cell design
Scientists set new temperature record
New view reveals Mars' icy history
A new radar map of Mars' mid-latitudes confirms that they are the remnants of a vast ice sheet hidden under the Martian rubble.

The icy leftovers have been found over a significant part of Deuteronilus Mensae, an area about halfway between the Martian equator and North Pole. The ice was mapped by the Italian Space Agency's Shallow Radar instrument on NASA's Mars Reconnaissance Orbiter.

"It's definitely a record of a different climate period," says Dr Jeffrey Plaut of NASA's Jet Propulsion Laboratory.

Today all that remains are thick ice piles buried at the foot of hillsides under rocky debris. "The debris protects them from sublimating," says Plaut, referring to the process of solid water ice evaporating into the air without any intervening liquid phase.

Plaut and his colleagues prepared their new ice map for presentation at this week's Lunar and Planetary Science Conference .
Changing climate

The ice is just a few metres below the rubble in some places, says Plaut, but can run a kilometre thick. The long lost ice sheet probably existed tens to hundreds of millions of years ago, based on the features of local impact craters, which are used to date landscapes on Mars.

And while that might seem like a long time, it's nothing compared to the billions of years that have passed since Mars might have been capable of supporting liquid water, he says.

"It's not all the way back to the earliest days."

That timing would seem to support the idea that Mars can have very long-term climate changes caused by the gradual wobble in the tilt of the planet's axis. The wide wobble creates periods when Mars' poles dip very low, allowing the Sun to shine more on the poles in their respective summer times.

That means warmer poles, which would cause polar ice to sublime into gas, thickening Mars' atmosphere so the water could fall as snow at lower latitudes.

This idea was put forward five years ago by Professor James Head III of Brown University, who presented numerous features in this same region that looked suspiciously like glaciated terrain on Earth.

"Essentially all of the features were known from the Viking spacecraft in the late 1970s," says veteran Mars scientist Professor Vic Baker of the University of Arizona.

New view

Head's work made the case yet again using much higher resolution images, says Baker. "Mars was screaming at us that it had a lot of water and ice."

He says the problem was the evidence was all based on the science of geomorphology, or land forms, which is not an area a lot of physicists put much stock in.

Now that a radar instrument is backing up the geomorphology that's been known for decades, "A lot of physicists will start working on it," says Baker.

One thing that's not likely to come of this is a rover mission to dig up the ice. A few metres of debris is not exactly within the current rover job description.

"It's more of a job for a backhoe," says Plaut.

Horny mother beetles fight for dung
Light-speed computing one step closer
Small asteroids 'just lumps of gravel'
Gene study reveals diverse gut zoo
Dinosaur extinction caused by asteroid: study
Study finds methane bubbling from Arctic
New view reveals Mars' icy history
Some nano-sunscreens 'come at a cost'
Dust bunnies could harbour toxic load
Aphid genome reveals its 'Achilles heel'
Tailored diet may slow down DNA damage
Scientist probe ballistic chameleon tongue
Moa eggshells yield ancient DNA
Toothbrush tech helps buses go green
Gene protects some Tassie devils from tumour
Smaller fish cope better with acidic water
Lunar mirror mystery solved
Parents give fewer bad genes than thought
Women on pill may live longer
Antarctic winds affect key ocean layer
Researchers uncover thalidomide mystery
Boost for evidence of early ocean
Ocean geoengineering may prove lethal
People leave unique 'germ print'
Rogue star on collision course
Butterflies 'fly early as planet warms'
Glaucoma may start in the brain
Tools push back dates for humans on Flores
Stem cell capsules to target broken bones
Ecstasy damages complex memory: study
Earliest animals flexed their muscles
Insomnia may shrink the brain: study
Experts call for 'resilience thinking'
Tutu's DNA could point to medical cures
Humble algae key to whale evolution
Happiness linked to healthy heart
Fewer cyclones, but more intense: study
Cosmic candles result of colliding stars
Flightless mosquitoes may curb dengue
Childhood poverty may leave its mark
Cautious response to technology strategy
Nanowire RAM to make ever-ready computers
Are non-smokers smarter than smokers?
There's iron in them thar Martian hills
'Shell Crusher' shark swam ancient oceans
Nanotechnology may tap into your mind
Small dogs originated in the Middle East
Brain 'hears' sound of silence
Swimmers 'may not understand' tsunami risk
Altruism surfaces on slow-sinking ship
Chile quake tops Haiti, but less deadly
Weedkiller 'makes boy frogs lay eggs'
Visit Statistics