- NASA Gives Up on Spirit Rescue, Preps Rover to Hibernate
- Strange Places on Mars: What Do You Want to See Next?
- Video: Model Dinosaur Tests Four-Winged Flight
- Solar Eclipse Images Show Dazzling Corona Detail
- A Year of Global Shipping Routes Mapped by GPS
Posted: 26 Jan 2010 11:56 AM PST
The NASA Spirit rover, which has been wandering Mars for the past six years, appears to be permanently stuck in the strange patch of Martian soil she's been lodged in for the past several months.
With winter approaching, Spirit's handlers have decided to put the rover into a hibernation mode intended to protect her electronics from temperatures that could drop close to the design limit of negative 67 degrees Fahrenheit.
"The Rover will be like a polar bear hibernating and it could be for many months, on the order of 6 months that the Rover will be in this state," said John Callas, the Rover project manager at the Jet Propulsion Laboratory, during a media teleconference. "This is not like the Phoenix mission. This rover is electrically active, but it has insufficient power to be awake each day."
Spirit's electronics were designed to withstand temperatures of negative 40 Fahrenheit while operating and negative 67 when hibernating. NASA scientists predict that the temperature will drop below negative 40, necessitating taking moves to protect the rover.
"The estimate is that the rover, even though it is getting cold, will stay within its design limits, but those were tested for a brand new rover fresh out of the box and this one has been on the surface for six years," Callas said. "These will be temperatures that are colder than anything we've seen on the surface of Mars."
After the winter, Spirit will be contacted and wake back up to continue her life not as the rover of yore but as a stationary scientific platform.
Steve Squyres, a planetary scientist at Cornell University and principal investigator for Spirit and Opportunity, tried to put a happy face on the this new phase of the mission.
"That imperative to drive is relaxed," Squyres said. "That enables us to focus on new classes of science that you can only do from a science platform that isn't moving around a lot."
In particular, he said that the team would focus on tracking Spirit's radio signal very precisely, which could allow them to determine whether the Martian core is solid or liquid through a telltale wobble in the planet's rotation.
"The way that Mars wobbles depends on its internal structure," said Squyres. "When you go through the math, if Mars has a solid core of iron, it will wobble in a certain well defined way. But if that core is liquid, it will wobble in an every so slightly different way. And by tracking the signal, we can distinguish between the two."
The Mars scientists are also excited about the area in which they've become stuck.
"The area has the highest concentration of sulfates we've seen anywhere on the planet," Callas said. "We were driving around on a crust of this stuff that was strong enough to support the rover and then we broke through it. We're very fortunate that this new landing site… turned out to be a good one."
The sulfates may have been formed by steam vents in the distant Martian past, Squyres said, and subsequently transported by water processes.
Despite the science that can be done at the site, the probable end of Spirit's career as a mobile unit seemed discouraging to JPL rover driver, Ashley Stroupe. A week and a half ago, the rover team changed their approach to getting the rover unstuck and experienced much greater success.
"We had a tremendous amount of hope," Stroupe said.
In the end, though, they ran out of time. Now, their main task is positioning the rover to capture the greatest amount of solar energy possible: the rover is currently tilted south, away from the sun in the northern sky. If they can reduce the tilt, Spirit may be able to periodically communicate with Earth throughout the winter. If they can't, it will be a long, silent winter for the robot.
Image: NASA/JPL. Spirit's self-portrait.
Posted: 25 Jan 2010 05:00 PM PST
<< previous image | next image >>
NASA's Mars Reconnaissance Orbiter has captured more than 13,000 images of the red planet's surface. And now, the space agency wants your input on what images to acquire next.
The High Resolution Imaging Science Experiment (HiRISE) camera is currently the most powerful camera on any NASA spacecraft. The images it has collected are truly amazing. They highlight how similar the Martian landscape is to Earth in some ways, as well as how otherworldly other parts of Mars can seem.
We've collected just a few of theoddest and most beautiful shots. If they inspire you to want to pick the next strange location for HiRISE to focus on, NASA has created a website where you can scan the planet's surface and make suggestions.
The image above shows a dune field on the floor of a crater made by an asteroid impact.
Click on any image in this gallery for a higher-resolution version.
Image: NASA/JPL/University of Arizona
Posted: 25 Jan 2010 03:49 PM PST
A hand-built model of an early flying dinosaur may explain exactly how the four wings of Microraptor gui helped it glide down from trees.
Basing their work on a cast of a very well-preserved fossil, University of Kansas scientists created a model airplane-like mock dinosaur made out of plywood, balsa, and carbon fiber. Then, they attached one of three sets of test wings of different configurations to the body with rubber bands. The wings even featured real bird feathers whittled into probable shapes.
"We went back and forth. We thought, maybe we'll do 3-D graphics and it'll look really cool. But it's more accurate to do the modeling directly from the specimen," said Dave Burnham, a paleontologist at the University of Kansas and co-author of a new paper on the work in the Proceedings of the National Academies of Sciences.
Microraptor gui was a small dinosaur species that lived about 120 million years ago. About two dozen specimens have been recovered from near Liaoning, China. The Kansas team was lent one well-preserved fossil, from which they began their reconstruction efforts.
With the model in hand, they were able to test how the animals might have glided, by attaching them to a catapult that imparted a consistent amount of thrust to send them flying through the air. By measuring the distances that the different wing configurations allowed the model dinosaurs to fly, they were able to determine which wing type would have been most efficient.
The biomechanical reconstruction of flying creatures not seen today is a difficult business. Burnham and his collaborator, University of Kansas paleontologist David Alexander, argue that the birds probably glided with their legs splayed out — not unlike a flying squirrel.
Others argue for a different wing configuration in which both sets of wings are parallel to each other, what they call a "biplane" configuration. Sankar Chatterjee, a paleontologist at Texas Tech, and R. Jack Templin, an independent scholar, say that instead of splaying out like a squirrel, the animal would have tucked its legs under itself.
"It seems likely that Microraptor invented the biplane 125 million years before the Wright 1903 Flyer," they argued in a 2007 PNAS paper.
The new tests may not have unequivocally settled the disagreement, but Burnham said the wing configuration suggested by the other group was not properly balanced and required too much weight in the head of the animal.
"The real animal would have had to have had a solid lead skull," Burnham said.
Video: David Burnham. You can watch the team's progression from simpler foam models that were hand-launched to more complex model-airplane–like varieties.
Posted: 25 Jan 2010 02:46 PM PST
The annular solar eclipse that was visible earlier this month in parts of Africa, the Indian Ocean and Asia yielded some beautiful photographs of the moon obscuring the light from the sun.
But none of them provided the kind of exquisite detail that a team of astronomers watching from the Marshall Islands captured during last summer's total solar eclipse. By combining 31 images of the eclipse shot with a Canon EOS 5D, the composite shows the incredible structure of the sun's corona stretching out from occluded central disc. The moon's surface details are also clearly visible.
The next total solar eclipse will occur on July 11 and will be visible only from the South Pacific. So, read our how-to guide on solar eclipse tourism and start saving those frequent flyer miles.
Images: Copyright 2009 Miloslav Druckmüller, Peter Aniol, Vojtech Rušin, Ľubomír Klocok, Karel Martišek, Martin Dietzel. Higher-resolution versions are available here.
Posted: 25 Jan 2010 01:04 PM PST
Scientists have come up with the first comprehensive map of global shipping routes based on actual itineraries. The team pieced together a year's worth of travel itineraries from 16,693 cargo ships using data from LLoyd's Register Fairplay and the Automatic Identification System, which tracks vessels using a VHF receiver and GPS.
A few hot spots logged the majority of journeys. The busiest port was the Panama Canal, followed by the Suez Canal and Shanghai.
"There is a strong similarity of statistical properties between shipping and aviation networks," lead author Bernd Blasius, a mathematical modeler at Carl von Ossietzky University, wrote in an e-mail. "But different ship types (e.g., container ships vs. bulk carriers or oil tankers) are characterized by different movement patterns."
The study will be published in a forthcoming Journal of the Royal Society: Interface.
Factoring in both the volume of ships and the number of other ports each is connected to, these are the top ports in the world:
1 Panama Canal
Image: Bernd Blasius
Citation: "The complex network of global cargo ship movements" Pablo Kaluza, Andrea Kölzsch, Michael T. Gastner and Bernd Blasius, J. Royal Society: Interface
|You are subscribed to email updates from Johnus Morphopalus's Facebook notes |
To stop receiving these emails, you may unsubscribe now.
|Email delivery powered by Google|
|Google Inc., 20 West Kinzie, Chicago IL USA 60610|