Discoveries
Artist's rendering of the Phoenix Mars Lander as the sun dips toward the martian horizon (CREDIT: JPL/Corby Waste)
After the landers of (Mars') summer have gone
Cue up Don Henley's "The Boys of Summer," tweak the lyrics a bit, and it's time to bid adieu to the Phoenix Mars Lander.
The craft's summer (Mars time) fling is over. Winter has set in around the planet's northern reaches, where Phoenix landed. The craft's solar panels no longer intercept enough sunlight to power the craft or keep it warm. So the National Aeronautics and Space Administration has ordered the Mars Reconnaissance Orbiter (MRO) -- the lander's radio relay station -- to stop listening for the its telltale signal.
But if the hardy little chemistry lab on a platter is now a memory, it lives on in the reams of data it's sent back on summer weather patterns, and especially on the soil and ice found at its landing site. Those may hold clues as to whether the landing site could become a temporary host for microbial life as the planet's orbit changes periodically, shifting the planet's climate much like changes in Earth's orbit triggers ice ages here.
Those changes on Mars have been neatly recorded by the MRO in rock formations far to southeast of the lander's site, in a region called Arabia Terra. The formal scientific results appear in the current edition of the journal Science. A version for the rest of us appears here.
The bottom line: Layered rock formations appear in four craters scattered across Arabia Terra. Some of the areas look as if they are petrified rice paddies. In reality, they appear to tell a tale of climate change occurring at time scales of roughly every 100,000 years and 1 million years.
These correspond to periodic cycles in Mars' orbit, which in turn affect the seasonal distribution of sunlight over its surface. One set of cycles occurs every 100,000 years, driven by wobbles in the planet's axis of rotation. That shifts Mars' tilt by tens of degrees and back from one period to the next. On Earth, by contrast, the comparable cycle shifts the planet's tilt by only 2.4 degrees roughly every 41,000 years.
Mars' 1-million-year cycle is traced to a second, more subtle shift in the tilt of its axis.
The pattern is most starkly revealed in Becquerel Crater, according the Caltech team, who analyzed the features in images from MRO's HiRISE camera. The crater sports a pattern where 66 layers, each roughly 10 feet thick, appear in 10-layer "bundles."
It's a bit like stacking two decks of play cards, and sandwiching a piece of cardboard between every 10th card.
When all is said and done, the crater is recording some 12 million years worth of climate shifts, says Kevin Lewis, a Caltech planetary scientist who wrote up the findings on behalf of himself and five colleagues who shared the labor.
So where does this leave the late, lamented Phoenix Mars Lander's contribution?
Peter Smith, the project's lead scientist, explains that first-cut studies of the soil the lander sampled revealed clays and carbonates -- minerals that on Earth form in the presence of liquid water.
During the mission, which enjoyed an extension along the way, the lander also picked up signs of salts and perchlorate. The salts, including potassium, sodium, magnesium, and chlorine, could easily be considered nutrients. On Earth, some microbes use perchlorate as a source of energy, in place of the sun, or heat from hydrothermal vents.
Dr. Smith suggests that even if the landing site is devoid of life now (a proposition the lander was not designed to test), it conceivably could grow hospitable when Mars' tilt changes to bring warmer temperatures to planet's polar latitudes. More-detailed studies of the lander's data should help test that notion.
Venus is on a roll
Venus, along with two co-stars, put on a great show earlier this week. But she's not finished. She appears in the ultraviolet and infrared in the pages of this week's issue of the journal Nature, courtesy of researchers with the European Space Agency's Venus Express orbiter.
The images are giving scientists a unique window on the torrid planet's atmosphere. It's one of many aspects of Earth's twin that scientists are exploring. They are trying to piece together the story of how two such closely related orbs could evolve such dramatically different surface environments.
Twins, he says? Earth and Venus are roughly the same size. But Venus is shrouded in clouds made largely of droplets of sulfuric acid. Its atmosphere is 93 percent carbon dioxide. This has set up a runaway greenhouse effect that keeps temperatures on the planet at a toasty 890 degrees Fahrenheit. Another contribution to the high heat: The planet's "day" is 243 Earth days long – a planetary version of a holiday roast slowly turning on a spit. To top it off, on Venus the sun rises in the west and sets in the east. So, think fraternal twins.
At ultraviolet wavelengths, as in the image to the left, the clouds show detailed patterns of light and dark. The dark patches represent a mysterious chemical or set of chemicals that absorb ultraviolet light.
The infrared information gives scientists a measure of cloud height and how temperatures change with altitude.
By combining information from these different wavelengths of light, Dmitry Titov, with the Max Planck Institute for Solar System Research in Lindau, Germany, and colleagues have been able to tease out a trio of broad atmospheric features above the planet's southern hemisphere.
From the equator to about 50 degrees south, clouds top out at a fairly consistent 23,600 feet. Convection – the same kind of process that triggers the growth of thunderheads on Earth in the summer – appears to be drawing the mystery chemicals up high to generate the patterns in the ultraviolet image.
From 50 degrees south to 70 degrees south, the cloud tops appear to spread smoothly, thanks to a fairly steady flow of winds. Temperatures are cool enough up there to allow a haze of sulfuric acid to form, masking the signature of any mystery material still welling up through the atmosphere. That amount is likely to be small. Unlike temperatures at low latitudes, here temperatures appear to fall with depth, rather than rise. This stifles convection.
At the pole, a dark ring in the ultraviolet signals a strong, hurricanelike vortex of winds whipping around the planet once every 2.5 Earth days. At the center of this high-speed vortex, cloud tops are lower, reaching a height of about 21,000 feet.
Researchers point out that many of the processes they are seeing on Venus are amped-up versions of similar processes on Earth.
The orbiter, which arrived at Venus in April 2006, is in its first overtime period. Its initial operating period covered 500 Earth-days of observations. But in February 2007, mission managers approved an extension that will keep the craft swinging around Venus until May 2009.
Photo Credit: ESA/MPS/DLR/IDA
NASA delays flagship Mars rover launch to 2011
For folks looking forward to the launch of another ground-breaking Mars mission next year, you’ll have to wait. Top officials with the National Aeronautics and Space Administration announced today that they have pushed back the launch of the Mars Science Laboratory by two years.
In the process, the agency’s green-eye-shade crew will have to come up with an extra $400 million for the project. That’s the delay’s cost on a mission whose price tag already is estimated at $1.88 billion before all is said and done.
The delay is the second in a year, with the project currently running about two months behind schedule.
Why the latest schedule shift? Blame it on an untimely technical glitch, a slower-than-expected assembly line for key parts (some of which were poorly made), the need to test the whole thing exhaustively, and Johannes Kepler, who first figured out how orbits worked.
It turns out that the best time to launch the mission is when the Earth and Mars are at their closest, about once every 26 months. Even if engineers could overcome the hardware problem they’ve detected in time to launch, say, in early 2010, Earth and Mars will have moved too far apart. So they have to wait another 26 months for a new launch opportunity.
With a billion-dollar price tag and an objective that aims to answer some fundamental questions about the potential for past or present life elsewhere in the solar system, NASA wants to get this mission right. The agency wants to avoid what Ed Weiler, who heads the agency’s science mission directorate, terms “a mad dash to launch.”
The Mars Science Laboratory “ranks just behind a manned mission in importance,” says Michael Griffin, NASA’s administrator. The money to pay for the delay is expected to come at the cost of delaying other science missions, officials add. First category up: Other Mars missions. Then they will turn to the planetary science community to help sort out additional options.
This is a technically complex project. The rover “dwarfs anything we’ve done before,” says Doug McCuistion, who heads the Mars Exploration Program at NASA headquaters. The “stack” — the rover, the descent stage that will ease the rover onto the surface, and the cruise stage, which keeps everything healthy en route to Mars — is largely complete, he says.
Each major element is complex enough to represent a mission in itself, he says. With all that riding to the red planet, the latest delay “was exactly the right thing to do.”
What’s your take on the decision?
Egg-laying time in a suburban front yard (Peter N. Spotts / The Christian Science Monitor / FILE)
Volunteering elbow grease for science
This week's fleeting meeting between the moon, Venus, and Jupiter brought out the closet astronomer in a lot of people.
Now take the urge to observe a step further. Hunt for planets around other stars. Help unravel the workings of Earth's climate. Or probe the mysteries of proteins. Scientists are looking for volunteers -- lots of them -- to answer some of science's biggest (and not so big) questions.
The latest call for help came this week from the USA National Phenology Network. Yep, the group's name is a mouthful. But the work is important. Seasons change, and the life cycles of plant, insects, and animals are keyed to them. And many of them take place right in front of our noses. Annual migrations, hibernation, the first appearance of leaves, open blossoms, fruit, and later dropped foliage are familiar sights to hundreds of millions of people. Researchers point out that shifts in these cycles represent some of the most sensitive biological signals that climate is changing. And those shifts can have a nasty effect on many of the plants and creatures that take their cues from changing seasons. But traditional sources of research money aren't large enough to build the kind of national reporting network needed to track these changes over many years. So, researchers are looking for volunteers – from schoolchildren to seasoned gardeners to professional scientists – to build a continent-size network of observers. Different sets of procedures are geared to different experience levels – beginner (Project Budburst, which Monitor colleagues have mentioned before here and here), intermediate, and "intensive."
For those who live on the US West Coast, there's another newcomer in search of help: The Quake-Catcher Network (QCN). The goal is to build the world's largest seismic network – one laptop and desktop computer at a time – in one of the world's most earthquake-prone regions. It's a joint program between Stanford University, the University of California at Riverside, and anyone who wants to volunteer a computer – more specifically, the computer's accelerometer. The QCN provides special software that monitors the accelerometers, which typically shut down hard drives if things get too shaky.
Amateur observers have taken part in a range of projects and made important contributions to science. Amateurs have been tracking the activity of variable stars for years. Within the past couple of years, professional astronomers have enlisted amateurs in the hunt for planets orbiting other stars — using home computers or telescopes. In the US, mechanics, housewives, and engineers have trained as US National Weather Service “Skywarn” spotters. Their observations feed into National Weather Service reports on the effects of severe weather and help forecasters decide when to issue severe-weather warnings. Another granddaddy: Cornell University’s annual winter bird-feeder watch. Over at Colorado State University, scientists have set up a growing national network of volunteer rain and snowfall monitors, who use a simple, inexpensive rain gauge.
But once computers landed on desks in homes and offices around the world, and the Internet linked them, the opportunities expanded. Hunting for ET, testing ideas about how proteins fold, even climate modeling all have harnessed home computers worldwide to help speed the pace of discovery.
These provide a great chance to lend scientists a hand. The projects are accessible to children and young adults. Teachers can harness many of them for their science classes. And they help folks become more attuned to what’s up in their natural ‘hood — whether it’s the backyard or out in the galaxy somewhere.
If you’ve been on a field project or you’re taking part in a citizen-science project, feel free to share your experiences. In the meantime, check out “Boinc” for a pretty exhaustive list of projects that could use your computer's surplus processing!
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