NASA, ESA and ISRO Satellites and Rovers observe Mars atmosphere and Comet Siding Spring

This artist's concept illustration depicts the Comet Siding Spring (2013 A1) flyby Mars and illustrates some of the NASA, ESA and ISRO satellites positioned to record the event.

Credit: Nasa, ESA

A comet the size of a small mountain is about to skim past Mars, and NASA hopes its spacecraft will be able to photograph the once-in-a-million-years encounter.

This March 27, 2014 image provided by NASA, ESA, and J.-Y. Li shows comet C/2013 A1, also known as Siding Spring, as captured by Wide Field Camera 3 on NASA's Hubble Space Telescope. 

Credit: AP Photo /NASA, ESA, J.-Y. Li

The comet, known as Siding Spring (C/2013 A1), is set to hurtle past Mars at a close distance of about 88,000 miles (141,600 kilometers).

The closest pass is expected to happen Sunday at 2:27 pm (1827 GMT).

Astronomers do not expect it will come any where near colliding with Mars, but they do hope it will be close enough to reveal clues about the origins of the solar system.

That is because the comet is believed to have originated billions of years ago in the Oort Cloud, a distant region of space at the outskirts of the solar system.

"Comets such as C/2013 A1 are essentially dirty icy snowballs with rocks and dust embedded in frozen gasses," said Dan Brown, an astronomy expert at Nottingham Trent University.

"It is on its first run towards the center of our solar system and its material is virtually unchanged by the rays of the sun and can give us an insight to the material composition of our early solar system 4.6 billion years ago."

Fast and powdery
The comet is flying through space at a breakneck speed of 122,400 miles per hour.

Another interesting thing about the comet, about a mile wide in diameter, is that it is only about as solid as a pile of talcum powder.

Illustration of the trajectory of Siding Spring, which will come close to Mars on Sunday.

NASA has manuevered its Mars orbiters to the far side of the planet so they won't be damaged by the comet's high-speed debris.

Even as the Mars Reconnaissance Orbiter, Mars Odyssey and MAVEN have been repositioned to avoid hazardous dust, scientists hope they will be able to capture a trove of data about the flyby for Earthlings to study.

NASA's two rovers, Curiosity and Opportunity, will turn their cameras skyward and send back pictures of the comet's pass in the coming days, weeks and months, the US space agency said.

"The orbiters will keep a close eye on the show," said Rebecca Johnson, editor of StarDate magazine.

"They'll study the comet itself, which is a small chunk of ice and rock. They'll also study the cloud of gas and dust around the comet, as well as its long tail," she said.

"And they'll measure how the gas and dust interact with the Martian atmosphere."

The comet has traveled more than one million years to make its first pass by Mars, and will not return for another million years, after it completes its next long loop around the sun.

The comet was discovered by Robert McNaught at ANU's Siding Spring Observatory in January 2013.

Its flyby of Mars is not likely to be visible to sky watchers on Earth.

But the encounter is of great interest to scientists, particularly since there are so many spacecraft on and around Mars to record it.

"As it zips toward the sun, it gives scientists a chance to see a relic from the distant past, a snowball that preserves the same ingredients that gave birth to our own world," said Johnson.

This image shows just how many satellites and probes humanity has sent to Mars. Some more successful than others, and we still have much to learn about our near neighbour.

NASA Mars Rover: Terramechanics research keeps rovers rolling

The Curiosity rover, which lifted off Nov. 26, 2011, will arrive at the Red Planet in August 2012. 

The rover, shown here during testing inside the Spacecraft Assembly Facility at the Jet Propulsion Laboratory in California, is about the size of a Mini Cooper and weighs roughly five times as much as the Spirit and Opportunity rovers.

In May 2009, the Mars rover Spirit cracked through a crusty layer of Martian topsoil, sinking into softer underlying sand. 

The unexpected sand trap permanently mired the vehicle, despite months of remote maneuvering by NASA engineers to attempt to free the rover.

The mission mishap may have been prevented, says MIT's Karl Iagnemma, by a better understanding of terramechanics—the interaction between vehicles and deformable terrain.

Iagnemma says scientists have a pretty good understanding of how soils interact with vehicles that weigh more than 2,000 pounds. But for smaller, lighter vehicles like the Mars rovers, the situation is murkier.

"There's a lot of knowledge in civil engineering about how soils will react when subjected to heavy loads," says Iagnemma, who is a principal research scientist in the Department of Mechanical Engineering.

"When you take lightweight vehicles and granular soils of varying composition, it's a very complex modeling process."

Karl Iagnemma

Now Iagnemma and researchers from Washington University in St. Louis and the Jet Propulsion Laboratory (JPL) in Pasadena, Calif., have developed a model called Artemis that accurately simulates rover mobility over various types of soil and terrain.

The model works much like a video game: A user plugs in commands to, for example, move the simulated rover forward a certain distance—instructions similar to those that NASA engineers give to rovers on Mars.

The simulation then predicts how the rover will move, based on the underlying soil properties, vehicle characteristics and a terrain's incline.

The team tested the model against observations in the field, including actual drive paths from previous Mars rovers, and found that the simulations behaved much like actual rovers in various terrains.



The researchers also performed experiments in the lab, rolling a replica of a Mars rover's wheel over Martian-like sand. The tests established relationships between wheel dynamics and soil properties—information that the team used to further refine the model.

Carmine Senatore

"Once you have a model you trust that is really representative of how the rover behaves, it can help mission planners make path plans in a safer way," says team member Carmine Senatore, who is a research scientist at MIT.

"It could say that this path looks shorter and faster, but if the soil is not what we expected, it may be much more dangerous, so it's better to go another way."

Senatore, Iagnemma, Raymond Arvidson of Washington University, and collaborators will outline the details of the model in a paper to appear in the Journal of Field Robotics.

Beach Sand and Cake Flour
For the most part, the terrain over which Mars rovers travel—including the most recent Curiosity mission—is relatively benign, consisting mostly of flat, firm surfaces.

But occasionally, rovers encounter more challenging environments, such as steep dunes covered in fine, loose soil.

"Think about the difference between beach sand, which you can walk on and even play volleyball on, and cake flour," Iagnemma says. "The reason [for that difference] goes down to the microscale of the material."

To know how much work is required for a rover to get over a dune, Iagnemma says one needs to understand the properties of an environment's soil.

To develop its model, the team estimated soil properties on Mars based on a variety of data sources, including measurements of the planet by orbiting sensors and images from the rovers themselves, as well as data on the amount of torque required to drive a wheel through a particular type of terrain.

The team coupled Martian soil data with properties of the rover, such as its size and weight, and developed a model to predict the likelihood and extent to which a rover may sink into a given terrain.

Iagnemma and Senatore refined the model with experiments in the lab. The researchers set up a bed of both coarse and fine soil, similar to sediment that has been observed on Mars. They built a straight track overhead, and attached a spare wheel from the Mars rover Opportunity.

Powering the wheel with a motor, the team observed the wheel's performance, noting how much the wheel sank into the soil, and the amount of torque needed to overcome sinking.

"Sometimes in a car you end up doing things like rocking it back and forth," Iagnemma says. "There's limited strategies for a Mars rover because it's not a very dynamic vehicle, and moves very slowly. So we have to be more creative and develop strategies to get out."

More information: Paper: onlinelibrary.wiley.com/journal/10.1002/(ISSN)1556-4967

Early NASA Viking rovers found life on Mars

A new analysis by an international team of scientists revealed that soil samples collected 36 years ago contained properties which indicate extraterestial microbes were indeed present.

The samples were initally collected by NASA’s Viking rovers and put through a series of tests called the Labeled Release experiments to see if certain byproducts of life processes, such as respiration, can be detected.

The results at that time, while promising, were complicated by a number of problematic factors, mainly the possibility of contamination.

For instance, while those experiments turned up a pair of organic chlorine compounds known as chloromethane and dichloromethane, the molecules also happened to be common in earthly chemicals such as the cleaning fluid used by the Mars rovers.

And with even the mere off-chance that they were introduced into the samples by an earthly source was enough to render the results inconclusive.

But the authors of the new study, published online in the International Journal of Aeronautical and Space Sciences, used an entirely different approach known as complexity analysis.

Instead of trying to make an assessment based solely on the presence of native compounds, they translated the data into sets of numbers to determine if whatever was present in the samples exhibited the same high degree of complexity that’s typically found with living systems on earth.

If the numerical data matched up, then, as the reasoning goes, it’s safe to conclude that there’s a very high statistical likelihood that some kind of living form was residing in that patch of dirt.

“Control responses that exhibit relatively low initial order rapidly devolve into near-random noise, while the active experiments exhibit higher initial order which decays only slowly,” the paper states. “This suggests a robust biological response.”

Although the logic makes intuitive sense, some detractors have argued that the technique still hasn’t proved to be reliable even when it comes to comparing living and non-living systems on Earth.

“Ideally, to use a technique on data from Mars, one would want to show that the technique has been well-calibrated and well-established on Earth. The need to do so is clear; on Mars we have no way to test the method, while on Earth we can,” planetary scientist and astrobiologist Christopher McKay, with NASA’s Ames Research Center in Moffett Field, Calif., reported.

Still, Joseph Miller, a neuropharmacologist at the University of Southern California’s Keck School of Medicine and one of the authors of the study, feels pretty confident in the team’s conclusions.

He said: “On the basis of what we’ve done so far, I’d say I’m 99 percent sure there’s life there.”

MARS HiRISE: The most powerful camera sent to space

The University of Arizona's High Resolution Imaging Science Experiment (HiRISE) camera is an incredible piece of scientific equipment. Currently circling the Red Planet aboard NASA's Mars Reconnaissance Orbiter, the instrument is capable of capturing photographs of the Martian surface at unprecedented resolution, averaging about 25 centimeters per pixel.

In the five and a half years that it's been snapping photos, HiRISE has capture close to 22,000 images of Mars' surface.

In doing so, it has provided a tremendous service to researchers throughout the scientific community, but equally impressive is the progress that HiRISE has made in the realm of public outreach, bringing stunning, high-quality imagery of the Martian surface to the general public on an international level.

Visit the MARS HiRise Image site

UK System could add to Mars Rover Brain Power

British scientists have announced a project they say could allow Mars rovers to roam autonomously around the planet.

The Seeker system was designed by engineers at the Rutherford Appleton Laboratory in Didcot as part of the European Space Agency's exploration efforts, the BBC reported.

It would allow a vehicle "to travel under its own steam with its own intelligence around a 6 kilometer (4-mile) route," engineer Kim Ward said.

Conventional rovers must follow commands sent from mission control on Earth that take 30 minutes to arrive at the Red Planet.

Seeker is designed to guide a rover Mars' hostile terrain autonomously to gather data.

Aron Kisbi, 24, a systems engineer at Appleton, called the system a leap forward after recent tests.

"We put the robot in the target area, leave it out there and it does the whole journey by itself, and that is what is really novel about the project," he said.

NASA: ATHLETE Rovers train in the desert

Two All-Terrain Hex-Legged Extra-Terrestrial Explorer (ATHLETE) rovers traverse the desert terrain adjacent to Dumont Dunes, CA.

The ATHLETE rovers are being built to be capable of rolling over Apollo-like undulating terrain and "walking" over extremely rough or steep terrain for future lunar missions.

Red Martian Powder is invasive and may be poisonous to human life

Clingy Red Martian Powder is a real Martian menace for NASA and the Rovers. (Image: NASA/JPL-Caltech)

Mars Rover Stuck

THE Mars rover Spirit, now bogged down in the Red Planet's soil, will need all the power it can muster if NASA scientists manage to get it moving again. So it's timely that researchers are getting a handle on why, the fine powdery dust is so invasive. It has collected on the vehicle's solar panels and stubbornly refuses to be cleared.

Martian Powdery Dust

Although the Astronauts on the Moon landing found the dust there to be very clingy, the Martian powdery dust is particularly invasive. This was noticed more than a decade ago when surprisingly large amounts stuck to the wheels of NASA's Sojourner rover. Static electricity was thought to be to blame, but no one could explain how the particles became charged. Now a team led by Keith Forward of Case Western Reserve University in Cleveland, Ohio, have an answer.

Static Electricity

The team believe that electrons jump back and forth between the dust grains as they collide in the ever-present Martian winds and dust devils, providing a build up of static. Smaller grains would be more likely to retain their extra electrons, giving them a negative charge, while larger grains would be left positively charged. To prove this they electrically charged grains of Hawaiian volcanic ash, chosen for its similarity to Martian dust, by blowing them around in a container (Geophysical Research Letters, DOI: 10.1029/2009gl038589).

Powdery Dust Toxicity

William Farrell of NASA's Goddard Space Flight Center in Maryland says this may help to combat the dust - important if people travel to Mars. "If the dust is toxic and you bring it inside [a human habitat] it could be extraordinarily bad." So, there is a lot more work to be done yet and even if the powdery dust is not toxic, it will be detrimental to human health if it invades the lungs.

Ooops! Mars Robots may have destroyed vital evidence of life

Mars landers and Rovers have been destroying signs of life, instead of identifying chemicals that could point to life. NASA's robot explorers may have been toasting them by mistake.

In 1976, many people's hopes of finding life on Mars collapsed when the twin Viking landers failed to detect even minute quantities of organic compounds - the complex, carbon-containing molecules that are central to life as we know it. "It contributed, in my opinion, to the fact that there were no additional [US lander] missions to Mars for 20 years," says Jeff Moore of NASA's Ames Research Center in Moffett Field, California.

The result also created a puzzle. Even if Mars has never had life, comets and asteroids that have struck the planet should have scattered at least some organic molecules - though not produced by life - over its surface.

Some have suggested that organics were cleansed from the surface by naturally occurring, highly reactive chemicals such as hydrogen peroxide. Then last year, NASA's Phoenix lander, which also failed to detect organics on Mars, stumbled on something in the Martian soil that may have, in effect, been hiding the organics: a class of chemicals called perchlorates.

At low temperatures, perchlorates are relatively harmless. But when heated to hundreds of degrees Celsius they release a lot of oxygen, which tends to cause any nearby combustible material to burn. For that very reason, perchlorates are used in rocket propulsion.