'Peeping Tom' Hubble Spies Mars' Full Frontal

As we approach the closest opposition with Mars in 10 years, Hubble took the opportunity to photograph the Red Planet's sun-lit hemisphere.

The Hubble Space Telescope has zoomed in on our Red Planet neighbor, spying some lovely detail in its mountains, plains, icecaps and clouds. The photo opportunity came as Earth and Mars near opposition - meaning we are currently at the point of closest approach to Mars in our orbit - but the peculiarities of planetary orbits has made this opposition extra-special.

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Although Mars and Earth's orbits are approximately circular around the sun, they are slightly elongated, meaning that both planets drift closer to the sun at certain times. Should Mars be a little closer to the sun during opposition, the Mars-Earth distance will be even smaller.

Earth orbits the sun every 365 days; Mars orbits the sun once every 687 Earth days.

Opposition occurs once every 26 months or so, but on May 22, the two planets will come within 0.503 AU (or 46.78 million miles) of each other, making this the closest opposition for 10 years. The closest opposition in recorded history occurred in 2003 when Mars came within 34.65 million miles from Earth.

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Of course, this celestial alignment produces a rare opportunity for Earth-bound astronomers. When Mars is at opposition, we can see the planet appear brighter in the night sky as it is located in an anti-sunward direction. And, as if peeking over the interplanetary fence, Hubble took the opportunity to see Mars' full frontal, giving us a global view of a completely sun-lit hemisphere.

Captured in this observation are some famous features, including Hellas Basin, Schiaparelii and Hugens craters, plus the cratered Arabia Terra and the north polar icecap:

NASA, ESA, the Hubble Heritage Team (STScI/AURA), J. Bell (ASU), and M. Wolff (Space Science Institute)

Features in the Martian atmosphere are also obvious, proving us with a snapshot of global cloud cover that can be used with previous Hubble observations to understand climate dynamics. Large scale changes on the planet's surface can also be tracked.

Mars Opposition: Close Encounter with the Red Planet

Hubble used its Wide Field Camera 3 (WFC3) to make the observation on May 12, resolving features a mere 30 kilometers (19 miles) across.

Although we are used to seeing Mars' surface features in mind-blowing resolution through the robotic eyes of spacecraft such as NASA's Mars Reconnaissance Orbiter, ESA's Mars Express and now the ISRO's Mars Orbiter Mission, there's something beautiful about an astronomical observation made from Earth orbit over nearly 50 million miles of interplanetary space. And Hubble's incredible optics are perfectly placed to see Mars in all its glory as it makes this special close pass of the Earth.

For more information on the Martian regions imaged and hi-res photos, check out the ESA news release.

Nearly one (Earth) year ago, NASA's Curiosity rover arrived at Mount Sharp, the key science destination of its mission. The rover has now spent three Earth years on the Red Planet, looking at rocks and environment to try to piece together the ancient past of Mars. Was it habitable for life? If so, did the life disappear? Why did the conditions change? These are all questions investigators are trying to learn the answers to. In this brief rundown of the science being done on Mount Sharp (officially known as Aeolis Mons), we've picked out some of the most intriguing and, frankly, beautiful photos of Curiosity's mountain.

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After extensive practice taking pictures of the rover, Curiosity's "selfies" are getting pretty amazing.

This is one of the latest ones

from Curiosity, showing it perched at the Marias Pass just after doing some drilling. While the selfies are used as a public relations tool, NASA also uses these pictures to monitor the condition of the rover in the harsh Martian environment. One thing the agency

is keeping an eye on is wheel damage

, for example.

Yep, that's a rock -- there are a lot of those on Mars. But look more closely at each one, and they reveal surprises. This particular rock is

embedded with silica

, a silicon-oxygen rock-forming compound that often shows up on Earth as quartz. It's an unusual find for Mars, and the team said it is going to take a closer look to see if it could preserve organic materials. Organics are considered building blocks of life, but not necessarily signs of life itself.

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Curiosity has a laser on board (called the Chemistry and Camera or ChemCam instrument) that shoots at rocks to figure out what they are made of. But for months, the auto-focuser malfunctioned and required multiple laser shots to be sent, slowing down the science. This image shows the result

after a successful software update

that takes several images and figures out how to target the focuser from there.

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In 28 pictures stitched together, Curiosity uncovered

an extensive network of mineral veins

at a site investigators dubbed "Garden City." These veins are created when a liquid cuts through cracks in a rock and leaves minerals behind. At the time this picture was taken, NASA was trying to figure out what the fluids were made of, and how the rock changed after the fluids touched it. It's all part of better understanding the ancient wet past on Mars and prospects for life.

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Sometimes you can't predict what will happen when you do science. In this case, Curiosity's drill did a test to see if this "Mojave" rock could be suitable to collect a sample...

and the rock shattered

. While it wasn't a total surprise that the rock broke, what made this test interesting was it

created a few rock chips

. This gave Curiosity an opportunity to look at what a new rock looks like before it gets all weathered by Martian wind and elements.

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In December, couple of building blocks of life came to light: Curiosity saw a

10-fold spike and fall in methane

around this time, and

detected carbon-bearing organic molecules on Mars

. While neither of these are necessarily signs of life, they point to conditions that could have been friendly for life at some point. Also, Curiosity got to flex its drill at the "Cumberland" rock target, which was a good thing as

a NASA senior review said the drill wasn't being used enough

(making it hard to justify the cost and complication).

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The very first hole

that Curiosity created in Mount Sharp revealed something exciting: the mineral it found was the same as one seen from orbit in the same region. Specifically, the rover

found evidence of hematite

, an iron oxide mineral that can precipitate out of water. Hematite was noted as a mineral of interest when the Curiosity landing site was being selected in 2010.

Image: Curiosity's path during the first few weeks at Mount Sharp in fall (Earth's northern hemisphere fall) 2014.

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