• [Article 6798]Rosetta’s Comet Target is a Rotating Two-body Comet


    What do You Do When Your Target Looks like a Rubber Ducky in Space?

    A sequence of 36 interpolated images of comet 67P/Churyumov-Gerasimenko each separated by approximately 20 minutes. The images were obtained by OSIRIS on July 14th, 2014 from a distance of approximately 12,000 kilometers (Courtesy: SA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA)

    Imagine designing a mission to land a probe on a comet. You have to make some assumptions about the comet nucleus, such as its shape, rotation rate, velocity, and what kind of ice it’s made of.  That’s what the planners for the European Space Agency’s Rosetta mission had to do, and this week, they’re getting the first up-close images of the target, Comet 67P/Churyumov-Gerasimenko. When the first views came from the spacecraft, I’m sure the scientists were probably incredibly excited to find out that this comet is not just your run-of-the-mill dented-in icy nucleus with a few jets. No way.  Instead, they’ve drawn the cosmic equivalent of a winning lottery ticket: a sort of double-lobed shaped nucleus that someone described as a rotating “rubber ducky” in space.

    Check it out for yourself.

    Yes, this is not like any other comet astronomers have seen.  And, it’s spurring a LOT of speculation. I used to study comets in grad school, and several questions came to mind immediately. For starters, how did it get to be this shape? Was this nucleus once two chunks of ice that somehow slammed together in the past and are now orbiting wildly in orbit? That would make it the first “contact binary” comet discovered.  Or, was it one huge chunk of ice that somehow got eroded or broken apart, leaving behind this rotating ducky-shaped object?

    To answer the question the mission scientists will use the Rosetta spacecraft’s instruments and cameras to study the surface characteristics of the comet. The data they gather will tell them the ice and mineral makeup. If the nucleus came from one body, then the whole thing should show the same mineralogical makeup. If it came from two different bodies, then the studies will show slight (or perhaps not-so-slight) differences in the ices and dust grains on the surface.

    When Rosetta gets to the comet (and the scientists decide to deploy it), it will send a small lander called Philae to settle down to the surface to give us some views from the comet, and also give some first-hand information about the surface materials it will be sitting on. Of course, with a two-body comet, now the big question is, WHERE do you land it?  In particular, if this comet turns out to be made of two different chunks of ice and dust, which side do you pick to study?

    Stay tuned because Rosetta is supposed to be at its closest approach to the comet on the morning of August 6th, 2014. It will be an exciting morning for another solar system “first”!



  • [Article 6792]Mars and Lebanon (The Meteorite)


    Curiosity Finds an Iron Meteorite on the Red Planet

     

    This rock encountered by NASA’s Curiosity Mars rover is an iron meteorite called “Lebanon,” similar in shape and luster to iron meteorites found on Mars by the previous generation of rovers, Spirit and Opportunity. Lebanon is about 2 yards or 2 meters wide (left to right, from this angle). The smaller piece in the foreground is called “Lebanon B.” (Image courtesy NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS/IAS/MSSS)

    I’m just putting this picture out here for you to look at. Go ahead, check it out. I’ll wait.

    For some reason, I find great beauty in looking at a piece of asteroid that landed on Mars, and that I can SEE it because of the Curiosity Mars rover. It never fails to amaze me that we have what amounts to a scientifically advanced Web cam on Mars, delivering up scenes like this pretty much every darned day!

    This looks like a typical meteorite with a surface that has been changed (heated and pitted) by its trip from its parent asteroid to the surface of Mars. It’s very similar to the type of iron meteorites we find on Earth, right down to the way it is shaped and its gray-black luster that looks almost like a dull metal.

    What you’re looking at here is a composite of several images taken (in the center, with circular rings around them) by the rover’s Remote Micro-imager, which is part of the rover’s Chemistry and Camera instrument (which helps planetary scientists study the chemical make up of materials) combined with images from the mast camera that helps the rover give us those wonderful distance shots on Mars.

    This iron meteorite fell to Mars at some point in the past and, like meteorites that fall to Earth, it was shaped, grooved, and heated by its passage through the atmosphere.  Areas on the rock that were not as heat-resistant as iron simply melted away, leaving behind rounded holes called regmaglypts. Planetary scientists are now debating just what caused some of the other cavities to form on the surface of this bit of space rock. One possibility is that the rock was somehow eroded along boundaries of the crystals in the rock. Did Mars weather place a role in shaping this rock after it survived its ride to the surface?  No way to tell without picking it up and looking at it. Another theory is that the rock may have had embedded olivine crystals that formed inside the parent asteroid, close to the core. Something destroyed them, leaving behind some of the odder pits on this rock.

    On Earth, if we found this type of meteorite, we’d hustle it off to a lab for more testing. But, since this thing fell to the Mars surface, Curiosity will have to tell us the tale, and astronomers will have to diagnose this from a distance. It’s a pretty cool discovery, and is actually the first for Curiosity. The Mars Exploration Rovers Spirit and Opportunity have each discovered meteorites, too. Mars appears to be a treasure trove of these space rocks!



  • [Article 6781]Lunar Landing Memories


    45 Years Ago

    Apollo 11 rises from the launch pad.

    On July 16, 1969 the first people to actually set foot on the Moon strapped themselves into a tiny Apollo 11 craft on top of a Saturn V rocket and blasted off. It seems hard to believe that all this time has passed, particularly for those of us who fully expected that within a decade or so, regular trips to the Moon would be ours to take.

    Sadly, things didn’t turn out that way. Our space program (in the U.S.) has not yet proceeded in the direction of daily or weekly trips to the lunar surface for fun, work, or colonization. But, the Moon is still an object of scientific (and possibly political) interest, even today. And, maybe in my lifetime, it will become that stopping-off point we all hoped for, useful to folks on their way to other places in the solar system.

    Not long before the Apollo mission, I became enamored of Star Trek. It seemed to me that with a little work (I didn’t understand all the technology at that point), humanity would soon be embarking on five-year missions of exploration, just as Captain Kirk and his crew was doing. Apollo 11 was just the first step. I anticipated missions to Mars that might start when I was in college, and regular trips to the Moon for tourists by the time I was in my 30s. And, starflight?  If I thought about it at all, I probably figured it would be something I’d see others do as I waved fondly farewell to them from my retirement cottage in Mare Imbrium.

    Well, things haven’t turned out quite that way. We have accomplished a lot in space — planetary missions, for example, have showed us what a HUGE and diverse place our solar system is. In the interim years between Apollo 11 and now, I’ve studied education and science journalism, worked as an astronomer, written many millions of words about astronomy and space in books, articles, documentaries, and blog entries, and I’ve come to realize that going to space is tough. It is, as John F. Kennedy said, “We do these things not because they are easy, but because they are hard.”

    So, as we embark on this week celebrating the accomplishments of Buzz Aldrin, Neil Armstrong, and Michael Collins 45 years ago, let’s think about what they really set in motion. Yes, Aldrin and Armstrong set foot on the Moon, and so did other astronauts after them. From them, people have learned to live and work in space. And, I hope that we’ll keep stepping out proudly to new places in space, if for no other reason than they cleared the path for us to do so. It’s not easy. In fact, it’s hard, both technically and politically. But, going to space is the right thing to do. It’s what will help our species live long and prosper. Our first steps will NOT be our last ones.