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Space Weathering: The Mars Connection

I don’t usually have much to say about Mars, for this site’s focus is on deep space — the outer Solar System and beyond. But with both the Mangalyaan and MAVEN Mars missions in progress, I’ll take this opportunity to mention new work out of MIT that deals with the effect of Mars on asteroids. The topic is ‘space weathering,’ the result of impacts from high energy particles and more. Richard Binzel and colleague Francesca DeMeo have been looking at disruption to asteroid surfaces, finding that close planetary encounters can explain an unusual fact: The surfaces of most asteroids appear redder than the remnants of asteroids that have crashed as meteorites to Earth.

Back in 2010, Binzel established what he sees as the basic mechanism. Main belt asteroids, orbiting between Mars and Jupiter, are exposed to cosmic radiation that changes the chemical nature of their surfaces. But take an asteroid out of the main belt and give it a close pass by the Earth and ‘asteroid quakes’ will occur, moving surface grains about and exposing fresh surfaces underneath because of the gravitational disruption. Binzel calls these ‘refreshed’ asteroids, and argues that when asteroids of this kind get too close to Earth, they break apart and fall to the surface as meteorites.

How Mars fits into this picture is a bit more of a stretch. At one-tenth the mass of Earth and only one-third its size, Mars seems unlikely to be considered a major gravitational disruptor. But placement is important, for Mars is closely situated to the main belt, which makes asteroid encounters that much more likely to happen. To study the effect, Binzel and DeMeo have tracked asteroids in the database maintained by the International Astronomical Union’s Minor Planet Center, which currently holds data on 300,000 asteroids and their orbits. The researchers’ new paper in Icarus maps orbital intersections between asteroids, Earth and Mars.


Image: Mighty Mars? It’s a small world, but its effect on asteroids passing by it is only now being understood. Credit: NASA.

The duo chose 64 asteroids and calculated the probabilities over the past half million years of close encounters that could have stirred up the asteroid surfaces. The paper focuses on a class of asteroids called Q-type, found primarily among Near-Earth Objects and matching ordinary chondrites spectroscopically over visible to near-infrared wavelengths. Because they are so similar to meteorites, they are assumed to have gone through weathering of the surface regolith, meaning older reddish grains have been churned and replaced. From the preprint:

Ten percent of the Q-types in our sample have not experienced Earth encounter on recent timescales. Thus, the orbited distribution of Q-types suggests Earth encounter is not the only resurfacing mechanism that counteracts the effects of space weathering. These non-Earth encountering objects do cross the orbit of Mars and show low Mars-MOID [Minimum Orbit Intersection Distance] values. We conclude that Mars is likely to play an important role in refreshing NEO surfaces due to its large mass and frequent asteroid encounters.

Two other mechanisms for refreshing an asteroid surface are considered, one being collisions between asteroids in the main belt, the other growing out of the results of the YORP [Yarkovsky, O’Keefe, Radzievskii, Paddack] effect, by which asteroids can be ‘spun up’ by photons streaming outward from the Sun. Binzel and DeMeo’s work found no conclusive evidence that either of these would play a significant role in refreshing asteroid surfaces, although the paper suggests further observations of small main belt asteroids to measure their effect.

So we’re learning more about asteroids even as we discover oddities like P/2013 P5, the unusual object that sprouts six comet-like tails [see What a Strange Asteroid Can Tell Us]. How both their composition and history define their characteristics is going to be an essential study for future efforts to reach and mine asteroids. This MIT news release offers more, including this comment from Vishnu Reddy (Planetary Science Institute), who was not involved in the research:

“On each of the asteroids we have visited so far, every one of them has shown a different kind of space weathering. So it appears that not only is composition an important factor, but also the location of the asteroid with respect to the Sun.”

The paper is DeMeo, “Mars Encounters cause fresh surfaces on some near-Earth asteroids,” Icarus Vol. 227 (1 January 2014), pp. 112-122 (abstract). See also Binzel et al., “Earth encounters as the origin of fresh surfaces on near-Earth asteroids,” Nature 463 (21 January 2010), pp. 331-334 (abstract).


Comments on this entry are closed.

  • David Cummings November 20, 2013, 11:39
  • Rob Flores November 20, 2013, 14:27

    I’ve been having arguments with super patriot Mars colonization advocates about the extra hazzards from larger meteorites striking the surface of Mars at high velocity because of Mars’ thin atmosphere. We should have a more accurate idea of how many Hazardous Meterors strike the Martian surface on the lower size of the spectrum. The larger strikes are visible, these are 30ft and larger new craters deteted from year to year. Presumably these meterors are on the order of bowlingball sized to man sized.
    Before we send substantial exploration crews we should find out just
    what the frequency and energy of the 1 cm to 15cm type impacts. While
    1cm sized impacts dont seem particularly harmfull such a projectile could still penetrate the vitals of criticial equiplent or just as worse vital organs of
    an astronaut.
    If it turns out 1cm and larger impacts occur with a high frequency it will slow Mars development somewhat as this will make free standing habitation structures a possible non-starter. It might mean a push into Cavemaking or Cave seeking as the safest Mars Shelters. I know that for larger colonization efforts it was thought this would be the main terrain type used by colonist due to radiation hazzards. Well If reports reveal Mars to be a shooting gallery it will be Standard Policy. It will also put damper on all those terraforming plans.

  • Mundus Gubernavi November 20, 2013, 23:52

    Not if we develop a viable asteroid deflection program. The Chelyabinsk incident made the UN more aware of the near-Earth threats; now we just need to organize the think tanks into a structured action so we can start building upon the info and technologies. Neil deGrasse Tyson recently co-hosted a discussion on the matter with the American Museum of Natural History and ASE, found here: http://www.youtube.com/watch?v=Hi54HYX9pWc

    I think once we get the momentum right, by the time we are able to terraform, asteroids won’t be a big problem.

  • ljk November 21, 2013, 12:52

    Regarding the MOM and MAVEN probes complimenting each other in their exploration of Mars, this is similar to the Venera 4 and Mariner 5 “joint” expeditions of 1967 at Venus, though without the whole Cold War background:


  • ljk December 9, 2013, 22:40


    Time Capsule for the Red Planet Blueprinted

    December 08, 2013

    The planet Mars may be on the receiving end of a “Time Capsule of Humanity” orchestrated by an international team of university students.

    The students are proposing to fly their time capsule to Mars via a CubeSat platform. This vehicle would carry a unique payload: a two-inch-diameter titanium sphere containing perhaps millions of digital photos, videos, audio files, and text messages from people all over the world.

    If their goal is achieved the mission would be the first time a CubeSat would be flown to another planet. It would also be the world’s first interplanetary space mission led by a non-government team.

    The entire mission is to be paid for by worldwide crowdfunding, with individuals having their digital creations survive for millennia on Mars for as little as 99 cents.

    Game changer

    The students are supported in their quest for Mars by a consortium of organizations, including the Massachusetts Institute of Technology (MIT), Explore Mars, and Remarkable Technologies, Inc.

    “This would be an extraordinarily challenging mission — a game changer,” said Dr. Paulo Lozano, Director of the MIT Space Propulsion Lab.

    The current plan is to launch the spacecraft into orbit as a secondary payload of a commercial space launch, and then accelerate the spacecraft to escape velocity — and on its course to Mars – perhaps using novel electrospray thrusters.

    Upload to Mars

    Individuals from around the world will be invited to upload their digital creations for the voyage to Mars.

    The digital files would be stored on the new quartz media being developed by such groups as Hitachi, Kyoto University, the University of Southampton, and others.

    Once on Mars, the quartz memory that holds the digital files promises to be durable for millions of years.

    Tools and resources

    While the students are shaping the essential science and technologies required for the mission, they are also looking for creative names of both the spacecraft and the Mars “time capsule” lander.

    The international team of students is targeting the end of this upcoming January to review and fine-tune the effort, establishing a detailed plan for a potential mission going forward.

    “This project is being done without profit by all supporting entities. We’re essentially giving the tools and resources to the students and saying, ‘Go for it,’” said Eric Knight, Founder and President of the Connecticut-based Remarkable Technologies, Inc.

    Early details of the mission can be seen here at:


    By Leonard David

  • ljk January 24, 2014, 11:08

    Mars Exploration Rover Opportunity celebrates ten years of operation on the Red Planet:


    Though minimally expected to function on Mars for 90 days, Steve Squyres once told me when asked that he figured the MERs would last 120 to 150 days on the surface, tops. Spirit did not stop signalling until 2010.

    Yeah, we got our money’s worth and then some from these wheeled robotic explorers.

  • ljk May 27, 2014, 9:18

    The New Search for Life on Mars

    Drew Ex Machina

    By Drew Lepage

    May 25, 2014

    The 1976 Viking missions to Mars have been our only attempts to date to search directly for life on another planet. The pair of identical Viking landers carried a trio of life detection experiments that were a marvel of early 1970s-era miniaturized technology. In addition, a gas chromatograph-mass spectrometer (GCMS) was carried to analyze the vapors released during heating of a sample to detect any organic compounds in the Martian soil. Unfortunately the scientific results of the Viking life detection experiments were ambiguous at best.

    While there was activity observed in all the life detection experiments with activity in one in particular (i.e. the LR or Labeled Release experiment) giving a positive result based on protocols established before the Viking flight, the lack of any detectable organic compounds in the Martian soil cast doubt on this interpretation.

    Full article and NASA Viking video here:


    To quote:

    Just a few days ago, I received my June 2014 issue of Scientific American and discovered a great article: “How to Search for Life on Mars” by Christopher P. McKay of NASA Ames Research Center and Victor Parro Garcia of the Center for Astrobiology in Spain. The authors, in addition to addressing the complications of the presence of perchlorates in the Martian soil, contend that the Viking life detection experiments were flawed from the start. These experiments, which had been developed back in the 1960s, used culture-based methods which are no longer considered definitive in detecting life even in terrestrial soil samples since only a small fraction of microbes can be grown in a culture.

    In this article, McKay and Garcia outline modern approaches to life detection experiments that rely on determining the presence of key biomarkers in the soil. Although there still remains the question of which of the multitude of potential biomarkers should be sought, these techniques are now advanced enough that instruments employing these new methods could be built and included in future Mars lander or rover missions. And while the authors were focused on the search for life on Mars in this article, these methods could also be applied to search for life or its traces in other biocompatible environments elsewhere in the solar system.

  • ljk June 4, 2014, 13:29

    H.G. Wells’ Remarkable Scientific Article About Evolution On Mars

    Mark Strauss

    5/29/14 9:30 am

    Ten years after publishing The War of the Worlds, H.G. Wells revisited the Red Planet, writing a non-fiction article speculating about what type of life existed on Mars. The provocative question he posed to readers: “Is it probable that evolution has gone upon exactly parallel lines on the two planets?”

    The essay, published in the March 1908 issue of Cosmopolitan magazine, was titled “The Things That Live On Mars” and featured astonishing illustrations (left and below) by William R. Leigh who, until then, had made a living painting landscapes of the American West.

    Years later, the famed science-fiction author Edmond Hamilton would describe the article — which he discovered when he was just four-years-old — as a defining moment in his life: “I looked at that magazine until it wore out. I wasn’t yet able to read it, to read the article, but those pictures! I sat and wondered if Mars was a long way off and if it was a very strange place.”

    Full article here:


    Link to his essay: