Springtime for Phoenix, Summer on Triton

Update: Even as I was typing this, the HiRISE team was posting a brand-new picture of a Martian avalanche! Check it out below …

Spring is in bloom on Earth’s Northern Hemisphere, melting snows, coaxing out budding leaves on trees, and otherwise making its mark on the landscape.

On northern Mars, spring has been revving up for a few months now, with signs of change all over the polar regions being captured by the HiRISE camera on the Mars Reconnaissance Orbiter.

Beetle-shaped sand dunes are starting to lose their carbon-dioxide icing:


Basaltic sand is being blown into dark streaks and starbursts on the thinning ice:


And avalanches are kicking up dust clouds as material gets loosened by the defrost and slides down steep cliffs:




Perhaps all the activity has NASA feeling extra hopeful that spring will also reawaken the Phoenix Mars lander, which has sat dormant through the long Martian winter, presumably frozen to death.

Starting yesterday and continuing through Friday, the Mars Odyssey orbiter will begin its third listening campaign for signs that the Phoenix has been reborn.

Although the lander wasn’t designed to last through winter’s chill, the craft was programmed with a Lazarus mode, on the off chance that an increase in spring sunlight might recharge the solar arrays and jolt Phoenix back into action.

In that instance, the lander should begin transmitting a beacon that the orbiter would relay to mission managers on Earth.

Previous listening periods in January and February produced radio silence.

Elsewhere in the solar system, the changing seasons have brought summer skies to Triton, Neptune’s largest moon.

Triton, of course, is *really* far away from the sun: It orbits Neptune at just under 221,000 miles (355,000 kilometers) from the planet’s surface, while Neptune is about 2.8 billion miles (4.5 billion kilometers) from the sun.

That means seasons on Triton change at a glacial pace—technically summer started in 2000, and it’ll be sometime around 2040 when fall sets in.

So astronomers using the European Southern Observatory‘s Very Large Telescope in Chile have had plenty of time to study how summer is affecting Triton’s thin atmosphere.

Results of their infrared analysis, released today, show that sunshine beating down on the southern hemisphere is pumping Triton’s atmosphere full of carbon monoxide.


Triton’s cratered surface, with the blue crescent of Neptune in the distance.

Astronomers already knew that Triton’s surface is coated in a variety of ices, including frozen carbon monoxide.

The new study shows that heat from the sun is turning some of that icy layer directly into gases, thickening the moon’s nitrogen atmosphere and enriching it with other compounds.

The team also confirmed trace amounts of methane in the atmosphere, which had been detected decades earlier by the Voyager 2 spacecraft. This methane probably also comes from vaporizing surface ices.

“We have found real evidence that the sun still makes its presence felt on Triton, even from so far away,” study leader Emmanuel Lellouch said in a statement.

—Mars images courtesy NASA/JPL/University of Arizona; Triton picture courtesy ESO/L. Cal├žada

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