Space Exploration |

13May 2013

Riding Hexapod Walkers on Dusty Alien Worlds

Speculative fiction is the home of countless machines that fly in space, yet resemble humanoid lifeforms. Scientists are now working on the next generation of robots that will blaze a trail in space by going where humans simply can’t maneuver on their own. Like so many things in the field of space exploration, the descendents of those working on these projects will be the ones to really reap the benefits of this research.

That being said, some scientists and engineers are beginning to consider the possibility of new types of craft that use human pilots while incorporating robotic structures to facilitate planetary exploration. Numerous remotely tele-operated vehicles like the Lunakhod and the Sojourner have already been used with great success to explore extraterrestrial surfaces. The use of human pilots in these past missions would of course been foolish, however, as technology advances it’s somewhat easier to believe that such endeavors in the future may be realistic. Robotics will undoubtedly become increasingly important as space travel becomes commonplace in the years ahead. Automatic piloting aren’t the only thing that these units will be useful for, however. Semiautonomous navigation devices are old news. Treads won’t be able to explore extremely treacherous terrain on rocky worlds. We need to figure out ways to get humans involved in planetary surface exploration.

One viable option to accomplish this may involve hexapod walkers similar to the one shown above. These units would be far more stable over irregular terrain than treads or wheels. Astronauts landing on other planets wouldn’t be able to work with equipment that’s as straightforward as the buggy used on the Apollo 15, 16 and 17 missions. By using six symmetrical legs, new robotic vehicles could descend vast gorges without tumbling the way conventional vehicles do.

Robotic algorithms can do more than merely pilot units as well. As brain interfaces become safer, astronauts may be able to directly interface with their vehicles. Hexapod legs could actually become extensions of their physical bodies. Some people have proposed constructing piloted robotic vehicles that look like some form of giant humans in order to speed up the learning process. Nevertheless, the human body isn’t exactly a great thing to model a machine after. While the human body might be balanced in its organic form, it wouldn’t really work as a machine. Humans require liquid in the inner ear canal to remain balanced. Hexapod units derive balance from their structure.

Interestingly, not all of a six-legged robot’s legs are necessary to remain upright. If a few of the legs were damaged, it might be able to still move. That makes this design particularly useful for astronauts who would be operating away from technical crews in extremely hazardous environments. Training problems might still be pretty serious, which is why some people have proposed chicken walkers and numerous other sophisticated designs as alternatives.

Conclusion

Industrial robotics have been used in spacecraft rendezvous and docking simulation conditions so these may be the best approach in the future once we figure out how to get humans to planetary bodies. It’s not hard to believe their use will continue to grow as we continue to push the boundaries of space exploration in the future. As we continue moving forward with our space exploration efforts, the involvement of humans should be considered as increases in our technological capabilities are realized. Brain interfaces and walker units may be integral components in these future planetary exploration efforts.

Reference:

Toralf Boge, & Ou Ma (2011). Using Advanced Industrial Robotics for Spacecraft Rendezvous and Docking simulation Robotics and Automation (ICRA), 1-4 DOI: 10.1109/ICRA.2011.5980583

Wilcox, B. (1992). Robotic vehicles for planetary exploration Applied Intelligence, 2 (2), 181-193 DOI: 10.1007/BF00058762

02May 2013

Meteorites May Reveal Mars’ Secrets of Life

Jason Carr ⋅ 2 Comments

In an effort to determine if conditions were ever right on Mars to sustain life, a team of scientists, including a Michigan State University professor, has examined a meteorite that formed on the red planet more than a billion years ago.

And although this team’s work is not specifically solving the mystery, it is laying the groundwork for future researchers to answer this age-old question.

The problem, said MSU geological sciences professor Michael Velbel, is that most meteorites that originated on Mars arrived on Earth so long ago that now they have characteristics that tell of their life on Earth, obscuring any clues it might offer about their time on Mars.

“These meteorites contain water-related mineral and chemical signatures that can signify habitable conditions,” he said. “The trouble is by the time most of these meteorites have been lying around on Earth they pick up signatures that look just like habitable environments, because they are. Earth, obviously, is habitable.

“If we could somehow prove the signature on the meteorite was from before it came to Earth, that would be telling us about Mars.”

Specifically, the team found mineral and chemical signatures on the rocks that indicated terrestrial weathering – changes that took place on Earth. The identification of these types of changes will provide valuable clues as scientists continue to examine the meteorites.

“Our contribution is to provide additional depth and a little broader view than some work has done before in sorting out those two kinds of water-related alterations – the ones that happened on Earth and the ones that happened on Mars,” Velbel said.

Image Credit: Michigan State University

The meteorite that Velbel and his colleagues examined – known as a nakhlite meteorite – was recovered in 2003 in the Miller Range of Antarctica. About the size of a tennis ball and weighing in at one-and-a-half pounds, the meteorite was one of hundreds recovered from that area.

Velbel said past examinations of meteorites that originated on Mars, as well as satellite and Rover data, prove water once existed on Mars, which is the fourth planet from the sun and Earth’s nearest Solar System neighbor.

“However,” he said, “until a Mars mission successfully returns samples from Mars, mineralogical studies of geochemical processes on Mars will continue to depend heavily on data from meteorites.”

Velbel is currently serving as a senior fellow at the Smithsonian Institution’s National Museum of Natural History in Washington D.C.

The research is published in Geochimica et Cosmochimica Acta (citation below), a bi-weekly journal co-sponsored by two professional societies, the Geochemical Society and the Meteoritical Society.

Source: Michigan State University

Reference:

Stopar, J., Taylor, G., Velbel, M., Norman, M., Vicenzi, E., & Hallis, L. (2013). Element abundances, patterns, and mobility in Nakhlite Miller Range 03346 and implications for aqueous alteration Geochimica et Cosmochimica Acta, 112, 208-225 DOI: 10.1016/j.gca.2013.02.024

22Apr 2013

Using Black Holes to Measure the Universe’s Rate of Expansion

Jason Carr ⋅ 4 Comments

A few years ago, researchers revealed that the universe is expanding at a much faster rate than originally believed — a discovery that earned a Nobel Prize in 2011. But measuring the rate of this acceleration over large distances is still challenging and problematic, says Prof. Hagai Netzer of Tel Aviv University’s School of Physics and Astronomy.

Now, Prof. Netzer, along with Jian-Min Wang, Pu Du and Chen Hu of the Institute of High Energy Physics of the Chinese Academy of Sciences and Dr. David Valls-Gabaud of the Observatoire de Paris, has developed a method with the potential to measure distances of billions of light years with a high degree of accuracy. The method uses certain types of active black holes that lie at the center of many galaxies. The ability to measure very long distances translates into seeing further into the past of the universe — and being able to estimate its rate of expansion at a very young age.

Published in the journal Physical Review Letters (citation below), this system of measurement takes into account the radiation emitted from the material that surrounds black holes before it is absorbed. As material is drawn into a black hole, it heats up and emits a huge amount of radiation, up to a thousand times the energy produced by a large galaxy containing 100 billion stars. For this reason, it can be seen from very far distances, explains Prof. Netzer.

Solving for unknown distances

Using radiation to measure distances is a general method in astronomy, but until now black holes have never been used to help measure these distances. By adding together measurements of the amount of energy being emitted from the vicinity of the black hole to the amount of radiation which reaches Earth, it’s possible to infer the distance to the black hole itself and the time in the history of the universe when the energy was emitted.

Getting an accurate estimate of the radiation being emitted depends on the properties of the black hole. For the specific type of black holes targeted in this work, the amount of radiation emitted as the object draws matter into itself is actually proportional to its mass, say the researchers. Therefore, long-established methods to measure this mass can be used to estimate the amount of radiation involved.

The viability of this theory was proved by using the known properties of black holes in our own astronomical vicinity, “only” several hundred million light years away. Prof. Netzer believes that his system will add to the astronomer’s tool kit for measuring distances much farther away, complimenting the existing method which uses the exploding stars called supernovae.

Illuminating “Dark Energy”

According to Prof. Netzer, the ability to measure far-off distances has the potential to unravel some of the greatest mysteries of the universe, which is approximately 14 billion years old. “When we are looking into a distance of billions of light years, we are looking that far into the past,” he explains. “The light that I see today was first produced when the universe was much younger.”

One such mystery is the nature of what astronomers call “dark energy,” the most significant source of energy in the present day universe. This energy, which is manifested as some kind of “anti-gravity,” is believed to contribute towards the accelerated expansion of the universe by pushing outwards. The ultimate goal is to understand dark energy on physical grounds, answering questions such as whether this energy has been consistent throughout time and if it is likely to change in the future.

Source: American Friends of Tel Aviv University

Reference:

Wang, J., Du, P., Valls-Gabaud, D., Hu, C., & Netzer, H. (2013). Super-Eddington Accreting Massive Black Holes as Long-Lived Cosmological Standards Physical Review Letters, 110 (8) DOI: 10.1103/PhysRevLett.110.081301

12Apr 2013

A New Paradigm in Space Mission Controls

Jason Carr ⋅ 2 Comments

Image: NASA

Images similar to the one above are what most of us think of when we hear mission control room. These rooms are typically used to control launch vehicles – a difficult task to be sure. Nevertheless, the new classes of Epsilon launch vehicles (Japan) are designed to accept input from regular terrestrial communications services and may render these facilities a thing of the past. The first of these vehicles are slated to launch this summer.

Satellite up-link systems are still needed to communicate with Epsilon space craft however they are designed to respond to server commands issued by regular users on Earth. This means that individuals who launch objects into space can work with them using the same equipment they use every day.

This type of capability is a potentially huge advantage for private industries that launch low Earth orbit (LEO) objects, such as satellites. Most businesses have had to place total faith in the mission control agencies that construct physical parabolic reflector dishes in the past to accomplish this. These dishes are needed to maintain basic lines of communication with objects in space. The organizations that run these ground stations can be rather bureaucratic, however. Bureaucracy of course can make the process difficult…and expensive.

Image: Japan Aerospace Exploration Agency (JAXA)

Epsilon missions on the other hand are designed to allow direct connections to the control software itself. This cuts out the middleman. Instead of having to contact an external organization that some change needs to be made, satellite operators can now do it alone. That’s a huge paradigm shift from the old way of doing things and the implications for future space efforts are fairly large.

Even if one was to ignore the potential political ramifications of a project like this, Epsilon launch vehicles might very well be safer than options that were previously available to commercial institutions. Additionally, mission control services are sometimes slow to react to satellite malfunctions. Because they are often contracted to watch over so many different systems, one might sometimes be overlooked by mistake (or simply ignored). Under this new paradigm, satellite owners could monitor their own property and as a result, could be expected to find problems before they escalate.

Educational opportunities shouldn’t be wasted along the way either. Regular terminals could be used to illustrate satellite controls to classrooms full of future engineers. Error handling algorithms would have to be employed to ensure that two commands weren’t executed at the same time. It’s easy to imagine that several people would try to get attention from a vehicle at once. Nonetheless, this type of thing could be amazing in courses dealing with physics, orbital mechanics, etc. Some individuals might even check out telemetry data simply because they find it fascinating. Communicating with a satellite for the first time can be exciting. Imagine being able to do so via your iPad or a mobile app.

Commercial ventures could make excellent use of these communications protocols as well. It wouldn’t be too difficult for a business venture to gain immediate control of the packages that they have launched into space. It’s not uncommon for organizations to put different piggyback modules on a single orbiting artificial satellite. If they were to do this with an Epsilon unit, each individual group could control its own module independently of one another. That would save a considerable amount of money when compared to the way things are currently done. It could also make space a great deal more accessible to private researchers who wouldn’t otherwise get a chance to send their experiments into space.

What do you think? Is this a positive advancement that should be further developed in the future, or are there issues that might arise by taking this communication out of the hands of mission control contractors?

14Mar 2013

The Benefits of Current Mars Research

Jason Carr ⋅ 3 Comments

Image Credit: NASA

Martian exploration is unquestionably a hot topic right now. Mainstream media outlets have largely focused on the most visible efforts of the Curiosity mission, and that’s a good thing. While people might be thrilled with the photographs that they have an opportunity to view on their screens however, they may be less familiar with the implications of this research for the future.

For instance, previously little was known about how the Martian permafrost segments melted, and some researchers weren’t even convinced that significant melting occurred. Mars has no visible oceans, and that means that there really isn’t anywhere for huge amounts of fluid to flow. Thanks to current research efforts, data collected thus far has put together a more complete image of the melt patterns of sedimentary rocks on the Red Planet.

This data is useful in helpful in determining whether life once existed on Mars. While permafrost melt patterns aren’t really able to confirm or deny astrobiology theories, they’re an awfully good start. Although it’s not possible to determine if there were ever organisms that evolved as a result of these flows simply by looking at them, some researchers may argue that further probes are necessary to delve into this area further.

Outside of the search for life (current or prior) on Mars, the seasonal melting model also suggests that oceans could eventually be constructed on the planet. This is particularly exciting where terraforming projects are concerned. With stores of carbon dioxide readily available in the Martian atmosphere, it may be possible to produce something similar to a greenhouse effect. Once this occurs, plant life would be able to produce readily available supplies of oxygen (that stuff we humans need to live) while cooling off the planet in the process.

The research efforts currently under way may help scientists to determine more efficient methods of accomplishing this Martian overhaul. For instance, scientists currently know that seasonal melts could provide the necessary ingredients for seasons that are somewhat similar to those on Earth. Winter phases might be useful for helping to reduce the planets’ cooling process as well.

Tracking weather patterns on the Red Planet might also help researchers who would prefer to manipulate the Martian climate with lenses or shields. Once enough is known about weather and geological patterns on Mars, large lenses could be built in geostationary orbit. These would increase the amount of sunlight directed towards the planet. While engineers would have to be extremely careful not to pump dangerous levels of ultraviolet radiation towards colonists, these mirror systems might help to provide necessary light and heat for the planet once we’ve colonized the planet.

Detecting salt solutions have also helped researchers to better understand the chemical composition of the Martian surface. Industrial facilities may some day work mines on the planet to retrieve resources that are necessary to sustain human colonists. This could, in essence, create an economy on the planet. Additionally, as mineral resources continue to become increasingly rare on Earth, these materials could prove invaluable to future Earth-based citizens as well. Rovers actually prove that mining on Mars could probably be done with current technology – yet another benefit derived from current research efforts.

Few will deny that we are witnessing history almost daily as results from the Curiosity mission are released to the world. While this is without question an amazing time, I think it’s important that we recognize the amazing research being conducted in the process – research that could potentially impact the future of humanity in ways we are currently unable to understand.

Reference:

Peters, G., Smith, J., Mungas, G., Bearman, G., Shiraishi, L., & Beegle, L. (2008). RASP-based sample acquisition of analogue Martian permafrost samples: Implications for NASA’s Phoenix scout mission Planetary and Space Science, 56 (3-4), 303-309 DOI: 10.1016/j.pss.2007.10.001

Amato P, Doyle SM, Battista JR, & Christner BC (2010). Implications of subzero metabolic activity on long-term microbial survival in terrestrial and extraterrestrial permafrost. Astrobiology, 10 (8), 789-98 PMID: 21087159

21Feb 2013

The Sobering Reality of Orbital Weapons Platforms

Jason Carr ⋅ 4 Comments

Image Credit: LucasFilm/LucasArts

Space warfare is quickly becoming a reality. Though people might often imagine that wars fought in space would be against some sort of extraterrestrial power, this might not be the case. It’s far more likely than human beings will someday war with one another. As with every other major venture, international law is involved with the development of space. Certain laws are in place to prevent countries from placing weapons of mass destruction into orbit.

Whether or not aggressive powers would actually abide by such laws is questionable. Researchers will have to find ways to defend against such threats. Believe it or not, there have already been patent applications for certain types of hypersonic orbital fighter jets. Craft like this would need some particularly unique engine designs. While nuclear power sounds like a good idea, the threat of fallout making it back into the Earth’s atmosphere is too great.

When orbital shipyards make construction of vessels in space possible, wings become completely foolish. In fact, spacecraft designed for combat would want to show as little surface area as possible. Giant cruisers might have become popular as a result of the magic of motion picture technology, but these designs are almost worthless if fighting an enemy in space.

Since there’s no reason to worry about lift in a practical vacuum, spherical designs are probably the most useful. Few film directors would want to show numerous balls floating around in space, but these designs would be the most practical. Engines would easily wrap around a sphere and propel the object in one direction or the other. Gravitational forces presented by other bodies in space could very well be used as slingshots to travel great distances without using too much fuel. Of course, they could also be considered hazards to avoid.

It’s likely that the first few confrontations in space would be rather awkward. Tacticians wouldn’t really know how to use their new weapons any better than naval officers used the Monitor and the Merrimac. Of course, for the time being any space weapons would be looked at as a deterrent rather than a full-fledged offensive device. Since the Cold War has long ended and military forces are focused on fighting small groups as opposed to nation states, the idea of deterrents has seemed to slip many people’s minds.

Peace is still a very real option. One might hope that humanity can avoid such conflicts. In fact, despite the idea that space warfare is inevitable, the exploration of space might very well help to prevent wars. Since resources are almost limitless in space, development and exploration could end many of the root causes of international conflicts. That would actually be better than having to prepare for an interstellar fight.

Reference:

Klein, J. (2004). SPACE WARFARE: A MARITIME-INSPIRED SPACE STRATEGY Astropolitics, 2 (1), 33-61 DOI: 10.1080/14777620490444740

Maogoto, J., & Freeland, S. (2007). The Final Frontier: The Laws of Armed Conflict and Space Warfare SSRN Electronic Journal DOI: 10.2139/ssrn.1079376

13Feb 2013

Small Business Contributions to U.S. Space Exploration

Jason Carr ⋅ 3 Comments

NASA OSBP Associate Administrator Glenn Delgado in conversation at JSC Industry Day. Credit: NASA.

Click to Open [PDF]

Many of you have likely been following the progression of the Mars Rover Curiosity in recent weeks. I’ve personally developed an interest in the types of tests that are being done on the red planet during the mission. This interest led me to think about the types of test equipment that is being utilized not only for experiments, but to ensure the safety of astronauts in manned missions as well. As I began to research this area further, I discovered an entire segment of expert service providers that are utilized by NASA to develop these specialized systems. Many of them are smaller firms and they’re doing some pretty incredible work for the agency. In fact, I discovered that NASA does a great deal to support small businesses each year via the Office of Small Business Programs (@NASA_OSBP).

Case Study: G Systems, L.P.

Systems and equipment used by NASA and other aerospace organizations aren’t the kind that you can just buy off the shelf. A piece of equipment that is used in space is obviously subjected to vastly different conditions than those found on Earth. Each must be rigorously tested before ever leaving the ground. To meet this need, NASA and other organizations often contract with highly specialized service providers to develop the equipment needed for individual space missions – including appropriate testing equipment required to maintain mission integrity. One such provider in my own backyard is G Systems, a growing, Texas-based engineering firm.

Pressurization and Vent System. Credit: G Systems, L.P.

Pressurization and Vent System, G Systems, L.P.

Unlike most test equipment available on the market today, the systems that G Systems develops are actually customized, turnkey models. That means that they can be expected to work whenever they’re turned on – without fail. Proper operation and maintenance are huge concerns in the aerospace industry since individual launch windows are often very small and involve a great number of interoperable systems. Having stable equipment to work with is needed because proper operation in space is absolutely vital. This is an industry where a single bolt means the difference between life and death.

While most of you probably have never heard of the company, several of the most recent space projects have involved G Systems’ contributions. For instance, one of their recent projects involved the Orion Multi-Purpose Crew Vehicle (MPCV). Having delivered test systems for the new Orion exploration crew vehicle test facility at the Michoud Assembly plant, G Systems played a major role in ensuring that this project went off without a hitch. They shipped data acquisition devices that collect and record information concerning the crew module’s structural strength.

G Systems also provided Orion researchers with data distribution devices that collect video of the capsule in addition to audio recordings and parametric information. Because the equipment is necessary for pressure tests, it’s actually capable of independently pressurizing the cabin. In other words, it can use supplies of air and helium to alter the pressure inside of the Orion capsule automatically. Data distribution tools also include an operator control terminal so that an engineer can set these options remotely if desired.

Data Acquisition System. Image Credit: G Systems, L.P.

Data Acquisition System. Credit: G Systems, L.P.

While the Constellation program has been shelved (sadly), the Orion project remains active today. Structural tests on the capsule are extremely important, and firms such as G Systems have played a key role in the program’s success thus far. While I don’t always agree with the actions taken by NASA administrators, I love the fact that they tap into the amazing talent available at private firms today. In doing so, the agency is supporting small business – always a good thing. This is yet another reason I remain a vocal proponent of NASA today.

Reference:

Archibald, R., & Finifter, D. (2003). Evaluating the NASA small business innovation research program: preliminary evidence of a trade-off between commercialization and basic research Research Policy, 32 (4), 605-619 DOI: 10.1016/S0048-7333(02)00046-X

Rapid Development of Orion Structural Test Systems. (2011). G Systems, L.P. Retrieved February 12, 2013, from goo.gl/7QW4p

Mansfield, C. L. (2013, January 14). NASA – National Aeronautics and Space Administration. NASA. Retrieved February 12, 2013, from goo.gl/zqjQK

31Jan 2013

Space ‘Scale’ to Weigh Black Holes

Jason Carr ⋅ 3 Comments

A new way of measuring the mass of supermassive black holes could revolutionize our understanding of how they form and help to shape galaxies.

The technique, developed by a team including Oxford University scientists, can spot the telltale tracer of carbon monoxide within the cloud of gas (mostly hydrogen) circling a supermassive black hole at the centre of a distant galaxy. By detecting the velocity of the spinning gas they are able to ‘weigh’ (determine the mass) of the black hole.

An image of NGC 4526 showing molecular gas. Image: NASA/ESA/Tim Davies

Detailed information on supermassive black holes, thought to be at the heart of most galaxies, is scarce: it has taken 15 years to measure the mass of just 60. The problem is that most other supermassive black holes are too far away to examine properly even with the Hubble Space Telescope.

The new method, when combined with new telescopes such as ALMA (Attacama Large Millimetre/submillimetre Array), promises to extend this black hole ‘weigh-in’ to thousands of distant galaxies. It will also enable the study of black holes in spiral galaxies (similar to our own Milky Way), which are hard to target using currently available techniques.

A report of the research is published in this week’s Nature (citation below).

The team demonstrated the new technique on the supermassive black hole at the centre of a galaxy, NGC 4526, in the constellation of Virgo. NGC 4526 was chosen as a test because it has been widely studied but the team believe the technique will work on a wide range of different galaxies.

Tim Davis of the European Southern Observatory, lead author of the paper, said, “We observed carbon monoxide molecules in the galaxy we were monitoring using the Combined Array for Research in Millimetre-wave Astronomy (CARMA) telescope. With its super-sharp images we were able to zoom right into the centre of the galaxy and observe the gas whizzing around the black hole. This gas moves at a speed which is determined by the black-hole’s mass, and the distance from it. By measuring the velocity of the gas at each position, we can measure the mass of the black hole.”

Dr Michele Cappellari of Oxford University’s Department of Physics, an author of the paper, said, “Because of the limitations of existing telescopes and techniques we had run out of galaxies with supermassive black holes to observe. Now with this new technique and telescopes like ALMA we will be able to examine the relationship between thousands of more distant galaxies and their black holes giving us an insight into how galaxies and black holes co-evolve. Importantly our ‘weigh-in’ technique will work for all kinds of galaxies, including spiral galaxies which are particularly difficult to observe with previous techniques.”

Dr Martin Bureau of Oxford University’s Department of Physics, an author of the paper, said: “The ALMA telescope is now in the final stages of construction and our team is currently bidding for time to use it for our black hole survey. If all goes according to plan we could begin our survey by the end of this year.”

Source: University of Oxford

Reference:

Davis, T., Bureau, M., Cappellari, M., Sarzi, M., & Blitz, L. (2013). A black-hole mass measurement from molecular gas kinematics in NGC4526 Nature DOI: 10.1038/nature11819

29Jan 2013

Ridges on Mars Suggest Ancient Flowing Water

Jason Carr ⋅ 2 Comments

A 3-D image of an impact crater in the Nilosyrtis area on the Martian surface shows long pipe-like ridges, fossilized evidence of ancient subsurface water flow. Credit: NASA Mars Reconnaissance Orbiter

Networks of narrow ridges found in impact craters on Mars appear to be the fossilized remnants of underground cracks through which water once flowed, according to a new analysis by researchers from Brown University.

The study, in press in the journal Geophysical Research Letters (cited below) bolsters the idea that the subsurface environment on Mars once had an active hydrology and could be a good place to search for evidence of past life. The research was conducted by Lee Saper, a recent Brown graduate, with Jack Mustard, professor of geological sciences.

The ridges, many of them hundreds of meters in length and a few meters wide, had been noted in previous research, but how they had formed was not known. Saper and Mustard thought they might once have been faults and fractures that formed underground when impact events rattled the planet’s crust. Water, if present in the subsurface, would have circulated through the cracks, slowly filling them in with mineral deposits, which would have been harder than the surrounding rocks. As those surrounding rocks eroded away over millions of years, the seams of mineral-hardened material would remain in place, forming the ridges seen today.

$Mineral deposits mark subsurface water flow A photo taken by the Mars Reconnaissance Orbiter shows ridges formed by fossilized subsurface water flow. Orientation of the ridges, mapped by researchers, is consistent with fractures formed by impact events. Credit: NASA and Mustard Lab/Brown University$

Mineral deposits mark subsurface water flow
A photo taken by the Mars Reconnaissance Orbiter shows ridges formed by fossilized subsurface water flow. Orientation of the ridges, mapped by researchers, is consistent with fractures formed by impact events. Credit: NASA and Mustard Lab/Brown University

To test their hypothesis, Saper and Mustard mapped over 4,000 ridges in two crater-pocked regions on Mars, Nili Fossae and Nilosyrtis. Using high-resolution images from NASA’s Mars Reconnaissance Orbiter, the researchers noted the orientations of the ridges and composition of the surrounding rocks.

The orientation data is consistent with the idea that the ridges started out as fractures formed by impact events. A competing hypothesis suggests that these structures may have been sheets of volcanic magma intruding into the surrounding rock, but that doesn’t appear to be the case. At Nili Fossae, the orientations are similar to the alignments of large faults related to a mega-scale impact. At Nilosyrtis, where the impact events were smaller in scale, the ridge orientations are associated with each of the small craters in which they were found. “This suggests that fracture formation resulted from the energy of localized impact events and are not associated with regional-scale volcanism,” Saper said.

Importantly, Saper and Mustard also found that the ridges exist exclusively in areas where the surrounding rock is rich in iron-magnesium clay, a mineral considered to be a telltale sign that water had once been present in the rocks.

“The association with these hydrated materials suggests there was a water source available,” Saper said. “That water would have flowed along the path of least resistance, which in this case would have been these fracture conduits.”

As that water flowed, dissolved minerals would have been slowly deposited in the conduits, in much the same way mineral deposits can build up and eventually clog drain pipes. That mineralized material would have been more resistant to erosion than the surrounding rock. And indeed, Saper and Mustard found that these ridges were only found in areas that were heavily eroded, consistent with the notion that these are ancient structures revealed as the weaker surrounding rocks were slowly peeled away by wind.

Taken together, the results suggest the ancient Martian subsurface had flowing water and may have been a habitable environment.

“This gives us a point of observation to say there was enough fracturing and fluid flow in the crust to sustain at least a regionally viable subsurface hydrology,” Saper said. “The overarching theme of NASA’s planetary exploration has been to follow the water. So if in fact these fractures that turned into these ridges were flowing with hydrothermal fluid, they could have been a viable biosphere.”

Saper hopes that the Curiosity rover, currently making its way across its Gale Crater landing site, might be able to shed more light on these types of structures.

“In the site at Gale Crater, there are thought to be mineralized fractures that the rover will go up and touch,” Saper said. “These are very small and may not be exactly the same kind of feature we studied, but we’ll have the opportunity to crush them up and do chemical analysis on them. That could either bolster our hypothesis or tell us we need to explore other possibilities.”

Source: Elsevier

Reference:

Lee Saper, & John F. Mustard (2013). Extensive linear ridge networks in Nili Fossae and Nilosyrtis, Mars: Implications for fluid flow in the ancient crust Geophysical Research Letters : 10.1002/grl.50106

15Jan 2013

A Celestial Primer

Jason Carr ⋅ 5 Comments

Universe

Understanding Space – Celestial Objects

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Space is a big, fascinating, and stunningly beautiful place. The universe is full of stars, galaxies, nebulae, planets, moons and much more. Ranging from lifeless rocky worlds such as Mercury to vast galaxies tens of thousands of light-years across, space is home to truly awesome displays of nature. Celestial objects, also known as astronomical objects, comprise the physical entities that make up the universe.

The universe has a hierarchal structure. On the smallest scales of astronomical objects, there is the Earth and our moon. The Earth is part of our solar system of eight planets while, in turn, our solar system is one of billions in the Milky Way galaxy. The Milky Way is one of 54 galaxies in the Local Group, a part of one of many superclusters that make up the universe – everything that exists.

The following guide, roughly in order from the smallest to the largest celestial objects, will help you to understand the scale of the universe, its hierarchal structure and some of the many fascinating things that lie beyond the borders of our world.

1 – Meteors

Meteorite Meteors are small, rocky debris floating around in the vacuum of space ranging in size from grains of sand to massive boulders. When these enter the atmosphere of Earth or any other celestial body, they are called meteoroids. These bombard us constantly, but the vast majority of them burn up as they descend into the Earth’s atmosphere. This is precisely what shooting stars are – small, burning debris making brief streaks of light in the night sky as they are vaporized. If a meteoroid is either large enough or travelling fast enough to make it through the atmosphere without being annihilated, it will make it to the ground, becoming a meteorite.

Fun Facts about Meteors

The largest known meteorite is the Hoba meteorite in Namibia weighing about sixty tons. It is the worlds heaviest naturally occurring chunk of iron and it is believed to have hit Earth’s surface about 80,000 years ago.
The best-known meteor showers are the Perseids and Leonids that fall every year in August and November respectively.
Some meteorites on Earth originated from Mars, such as the famous Allan Hills 84001 meteorite. This one attracted a great deal of attention due to the presence of possible fossilized remains of Martian bacteria.

2 – Comets

Comet Comets are small, icy celestial bodies composed of a nucleus, coma and tail. The nucleus comprises the solid bulk of the comet and ranges in size from a hundred meters to a few dozen kilometers. Comets are characterized by spectacular comas and tails, leaving a long trail of bright matter behind them. There are over 4,000 known comets in the solar system and some have been known since ancient times. Many comets have enormous, elliptical orbits around the sun, many reaching maximum distances far beyond the orbit of Pluto.

Fun Facts about Comets

Extremely bright comets typically appear no more than once every decade. These are known as the Great Comets and are visible to the naked eye.
One of the most famous comets, Halley’s Comet (shown above) may have been the Star of Bethlehem referred to in the Bible. Halley’s Comet makes an appearance every 75 years.
The Great Comet of 1811 was clearly visible for almost nine months. It had a coma fifty percent longer than the diameter of the sun – up to 1,000,000 miles long!

3 – Asteroids

Asteroid Mission Asteroids are small celestial bodies of which there are many millions around the Solar System. Asteroids orbit the Sun just like planets do, but they are far smaller. Because of this, they also have negligible gravitational pulls and no atmospheres to speak of. Also, because of their lack of size and gravity, smaller asteroids are irregularly-shaped rather than near-perfect spheres like planets and dwarf planets. The majority of known asteroids are located in the Asteroid Belt between the orbits of Mars and Jupiter. Asteroids are also found in the Kuiper Belt beyond the orbit of Pluto.

Fun Facts about Asteroids

An asteroid impact may have been what wiped out the dinosaurs in the Cretaceous-Palaeogene extinction event 65.5 million years ago.
Some asteroids have moons (satellites), such as 243 Ida and its tiny moon, Dactyl. Until its discovery, it was thought that only planets had moons.
Asteroids may one day be used for mining thanks to their abundance of valuable metals and materials.

4 – Dwarf Planets

Dwarf planets are characterized as small planets that are massive enough to have gravitational forces great enough make them spherical in shape. They also orbit the sun directly. Most notably, Pluto is a dwarf planet that was reclassified as such in 2006, until which point it had, since its discovery in 1930, been described as the Solar System’s ninth planet. All of the five known dwarf planets are considerably smaller than the Earth’s Moon. Dwarf planets may also have their own moons. Pluto, for example, has at least five. Dwarf planets are too small and do not have a high enough gravitational pull to be able to retain any more than a trace atmosphere.

Fun Facts about Dwarf Planets

Ceres, in spite of being the smallest known dwarf planet, was the first one discovered due to the fact that it is the largest non-planetary body in the inner solar system. It was discovered in 1801.
All other dwarf planets are found in the Kuiper Belt extending beyond the orbit of Pluto.
In 2015, NASA’s New Horizons space probe will visit the dwarf planet Pluto and take the first ever photos of its surface.

5 – Moons

Europa - Moon Moons, known as natural satellites in the scientific community, are objects ranging in size from tiny asteroids to bodies larger than the planet Mercury. They are gravitationally bound to their host planets, just as the Moon is to Earth. Earth, of course, has only one moon, but some of the other planets in the Solar System have dozens. In total, there are at least 176 moons in the Solar System. Mercury and Venus have none as far as we know, while Mars has two and the gas giant planets have dozens. The first moons discovered around other planets were the four Galilean moons of Jupiter in 1610 by Galileo.

Fun Facts about Moons

Many smaller moons are captured asteroids, pulled into the orbit of planets by powerful gravitational pulls. The two Martian moons, Phobos and Deimos are two such moons.
One of Saturn’s moons, Titan, is the only moon in the Solar System known to have a thick atmosphere. Because of this and other factors, it remains one of the first places in the Solar System to search for extraterrestrial life.
Jupiter has more moons than any other planet in the Solar System with a total of 67! The four largest of these are Io, Europa (shown on right above), Ganymede, and Callisto. Ganymede is actually larger than the planet Mercury. These four moons are known as the Galilean moons.

6 – Planets

Planets There are a total of eight planets in our solar system. Our solar system is comprised of the inner planets and the outer planets. The inner planets, in order of distance from the Sun, are Mercury, Venus, Earth, and Mars. Far beyond the orbit of Mars lie the outer planets, Jupiter, Saturn, Neptune and Uranus. These four planets are gas giants and, thanks to their size and gravitational influence, they each have numerous moons. Gas giants have no known solid surface. The planets of the Solar System vary dramatically. Mercury is a lifeless rock, Venus is a hellish inferno, Earth is home to the only forms of life that we know of and Mars still remains our first candidate in the search for extraterrestrial life either long dead or still present. Since 1995, many hundreds of planets have been discovered orbiting other stars as well. These are known as extrasolar planets.

Fun Facts about Planets

There are more than 850 planets orbiting stars other than our own (the Sun), and more are being discovered every week in large part due to the work of the Kepler Space Telescope.
Venus is the hottest planet in the Solar System with surface temperatures high enough to melt lead and air pressures as high as those one kilometer under the sea.
Water, a key ingredient for life as we know it, is common throughout the Solar System. Water ice is widely distributed on Mars and exists on the Moon, many comets and asteroids, and on various other astronomical bodies.

7 – Stars

Stars form the center of solar systems, just like our own star, the Sun, is the center of our own Solar System. When you look up at the sky on a clear night, you can start to grasp the vastness of space and the countless trillions of stars in the universe. The vast majority of stars are far more massive than even the largest planets, with the smallest ones being considerably larger the Jupiter and the largest ones being hundreds times bigger than the Sun. The Sun is nothing special as far as stars go and, in fact, there are billions of other stars just like it in our galaxy alone. Just like the Sun, many other stars host planetary systems, some of which may be very much like our own (and possibly home to extraterrestrial life). Stars are classified by spectrum types and are designated by letters. Our sun is a class G star.

Fun Facts about Stars

The largest known star is the red hypergiant called VY Canis Majoris. 3 billion kilometers (about 1.86 billion miles) in diameter, the star would extend further than Saturn’s orbit if placed in our Solar System.
Our own star, the Sun, is approximately 1.4 million kilometers (nearly 870,000 miles) in diameter.
The nearest star to Earth other than the Sun is the triple-star system, Alpha Centauri, 4.3 light-years away. 4.3 light-years equates to approximately 40,000,000,000,000 kilometers. Travelling at 252,800 km/h, the speed of the fastest man-made object, the Helios 2 space probe, would take around 18,000 years to reach it.

8 – Galaxies

Galaxy Stars make up galaxies such as our own galaxy, the Milky Way. The Milky Way is one of many billions of galaxies in the known universe. The Milky Way alone contains between 100 and 400 billion stars. Galaxies are vast, gravitationally bound systems containing not only stars, but also nebulae, rogue planets (planets without a host star) and various other celestial bodies. They fall into three broad classes described as elliptical, spiral and lenticular galaxies. Our own galaxy is a barred spiral galaxy characterized by an extremely bright and dense center of stars surrounded by swirling arms. Our own star system lies in one of the arms of the Milky Way orbiting the galactic center at a distance of 26,000 light-years (each light-year is roughly 6 trillion miles). The nearest proper galaxy beyond the Milky Way is Andromeda, about 2.5 million light-years away across a virtually empty void.

Fun Facts about Galaxies

The most distant galaxies tell us about the history of the universe. This is because we see them as they were when the light left them – effectively, we are looking back in time.
There are only three galaxies visible to the naked eye from Earth. These are the dwarf galaxies known as the Small and Large Magellanic Clouds and the Andromeda Galaxy.
There are at least 100 billion galaxies in the known universe, but there may be dozens times more than that.

9 – The Universe

Universe2 The observable universe comprises absolutely everything that we can see from Earth. Anything that is further away than the edge of the observable universe is invisible to us due to the fact that the light has not yet completed the long journey to Earth. The furthest we can see is approximately 13.75 billion light-years. The universe is made up of superclusters containing clusters of galaxies such as the Local Cluster where our own Milky Way galaxy is located. What lies beyond the observable universe is not known, although the universe is still generally thought to be finite. The universe is believed to have been created by the Big Bang and has been rapidly expanding ever since.

Fun Facts about the Universe

The universe is approximately 93 billion light-years in diameter, but due to the fact that the universe is expanding, we can still see things that are too far away, because we are seeing them as they were when they were closer to us.
The largest known object in the universe is the Sloan Great Wall, an enormous wall of galaxies about 1.38 billion light-years in length.
The size of the universe and the number of galaxies and stars in them suggest that life-supporting worlds, although clearly rare, could easily number in the billions.

Honorable Mention – Black Holes

Black holes are perhaps the most fascinating and bizarre of all the objects in space. Sometimes, when a star dies, it starts to collapse, the matter of which it is composed becoming more and more densely packed. Eventually, the star is so massive that its gravitational pull becomes so great that the escape velocity reaches the speed of light. When not even light is able to escape the surface, the star becomes invisible and only detectable by its influence on the surrounding area. The black hole is composed of an event horizon that marks the point of no return. Additionally, black holes have a gravitational singularity in the center that is infinitely dense, yet has no volume. At this point, the laws of physics simply break down, making black holes the most enigmatic objects in existence. Black holes are thought to exist in the center of many galaxies, including the Milky Way.