Astronomy Now Online
Home Magazine Sky Chart Resources Store


Top Stories


Did life need asteroid bombardment?

...A period 3.9 billion years ago when Earth was peppered with impacts by large asteroids may have created an environment in which primitive life could take hold, rather than destroying that life...

read more

Mystery of millisecond pulsars solved

...Astronomers have watched a pulsar be spun up in real time by its companion star, turning it into an incredibly fast millisecond pulsar rotating a breakneck 592 times per second...

read more

Doomed planet may have been drenched in water

...A small exoplanet full of water may have been swallowed up by a dead white dwarf star, according to anomalous readings of hydrogen in the star's helium-rich atmosphere...

read more



Spaceflight Now +



Subscribe to Spaceflight Now Plus for access to our extensive video collections!
How do I sign up?
Video archive

STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.

 Play

STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.

 Play

STS-118: Highlights

The STS-118 crew, including Barbara Morgan, narrates its mission highlights film and answers questions in this post-flight presentation.

 Full presentation
 Mission film

STS-120: Rollout to pad

Space shuttle Discovery rolls out of the Vehicle Assembly Building and travels to launch pad 39A for its STS-120 mission.

 Play

Dawn leaves Earth

NASA's Dawn space probe launches aboard a Delta 2-Heavy rocket from Cape Canaveral to explore two worlds in the asteroid belt.

 Full coverage

Dawn: Launch preview

These briefings preview the launch and science objectives of NASA's Dawn asteroid orbiter.

 Launch | Science

Become a subscriber
More video



Victoria provides Opportunity to view Mars' geological history

BY KEITH COOPER

ASTRONOMY NOW

Posted: 24 May, 2009

Opportunity’s two-year stay in Mars’ Victoria Crater is now bearing fruit, with the publication of the first major analysis of what the Mars Exploration Rover found.

Details present in the report featured in the 22 May edition of the journal Science describe a crater carved by wind and water erosion, and a strong indication that the water was mostly underground rather than running freely on the surface. The water appears to have come and gone several times billions of years ago, with the wind continuing the erosion until the present day.

Opportunity studying scalloped rocks inside Victoria Crater's Duck Bay.

Image: NASA/JPL–Caltech.


Opportunity arrived at the 750-metre wide Victoria Crater in September 2006 and cautiously drove in, inspecting layered rocks in steep cliff faces and shallow alcoves. The alternating cliffs, alcoves and outcroppings indicate that the crater has, over time, widened by a quarter as wind erosion has caused certain parts of the crater rim to crumble, filling in the crater bowl so it is now only 75 metres deep.


Opportunity spent considerable time examining one alcove in particular, nicknamed Duck Bay. The deeper into the crater the exposed sandstone rock goes, the older it is, and the rover detected more aluminium and silicon in the lower layers of Duck Bay, and less sulphur and iron. Opportunity also found relatively large ‘blueberries’ – small spherules of an iron-rich mineral called hematite, which forms in the presence of water.

However, in the higher layers and around the crater fewer and smaller blueberries were seen, indicating that the water action took place deep underground before the crater was excavated millions of years ago. On the approach to Victoria, Opportunity also found rocks containing minerals such as kamacite and troilite, which are common constituents of meteorites. It is tantalisingly possible that these are fragments of the rock that smashed into the Meridian Planum region on Mars to create Victoria all that time ago.

Victoria Crater imaged from orbit by the Mars Reconnaissance Orbiter.

Image: NASA/JPL/University of Arizona.


Many of the characteristics of Victoria Crater are similar to the much smaller Endurance Crater, which Opportunity explored shortly after bouncing down onto the surface in 2004. The two craters are six kilometres apart.


“It shows that the processes that we investigated in detail for the first time at Endurance Crater are regional in scale, [indicating that] the kinds of conclusions that we first reached at Endurance apply perhaps across Meridiani Planum,” says Opportunity’s Principal Investigator, Steve Squyres of Cornell University, USA.


Opportunity is now trekking across the red landscape to an even larger crater called Endeavour, which is 22 kilometres wide and currently still 16 kilometres away from the rover, its crater rim just beginning to peep over the horizon. Meanwhile, on the other side of Mars, Opportunity’s twin, Spirit, has got itself stuck in spot of bother: a sand trap that is holding the rover hostage as it spins its wheels. Opportunity fell prey to a similar sand trap that the mission team nicknamed Purgatory Dune, after it held the rover for six weeks in 2005 before it could work its way out.


“[Spirit] seems to be in a unique combination of soft, sandy material and slopes that we haven’t encountered yet,” says Cornell’s Jim Bell, who manages the colour panorama (Pancam) cameras on both rovers. “Neither one has been particularly problematic in the past, but the combination of the two has us bogged down. We’re not calling this purgatory for Spirit yet, but it has that potential.”

Spirit struggles in the deep, soft dust. Image: NASA/JPL–Caltech.

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.