Rendez-vous with a Comet

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In the cold reaches of space millions of kilometers from Earth, a ten-year journey is coming to an end and an era of discovery is about to begin. Rosetta, a spacecraft built and launched by the ESA has finally reached its target, meeting up with the comet 67P/Curyumov-Gerasimenko somewhere between the orbits of Mars and Jupiter. We don’t have any vehicles powerful enough to launch Rosetta into the same orbit as the comet, so it’s been a long and lonely trip for the little craft, slingshoting its way around the solar system to make the trip. “After ten years, five months and four days travelling towards our destination, looping around the Sun five times and clocking up 6.4 billion kilometers, we are delighted to finally announce ‘we are here'”, said Jean-Jacques Dordain, the director general of the ESA.

Rosetta’s mission is to study the comet up close, to find out what it’s made of and how it changes as it goes around the sun. As I explained in an earlier post, comets are some of the oldest objects in the Solar System, so learning more about them will help us understand the early history of our neighbourhood. Comets may have seeded the planets of our solar system with water and organic molecules, and this mission will provide a wealth of information about the physical and chemical processes in these ancient objects.

Rosetta went into hibernation for the last leg of its journey to conserve power. It awoke on schedule in January and pinged to control room back on Earth, to the great relief of the researchers. Since May, it’s made a series of ten rendezvous manuevers to adjust its speed and trajectory to match the comet’s. Now that it’s closer to the comet, it’s started collecting data and sending back pictures.

Using its OSIRIS camera, Rosetta recorded changes in the brightness of the comet’s coma — its envelope of gas and dust — in April and June. It also used the MIRO instrument to observe that the comet was losing water vapour into space at a rate of around 300 milliliters per second (that’s roughly a soda can per second, or a ton of water an hour). It also measured the comet’s temperature, roughly -70ºC.

At the moment, Rosetta is around 100km from the comet’s surface, but the plan is to get closer still. Over the coming weeks, the spacecraft will make its way to 50km from the surface before settling into a circular orbit 30km out. Rosetta will keep observing the comet throughout, studying it with its bevy of 11 instruments and scanning the surface for a docking site for the lander, Philae. Philae is expected to land on the surface of the comet in November and study it more closely. Nobody knows how long Philae will survive on the comet, so it’s programmed to make the most important measurements in the first couple of days, though hopefully it will be able to keep providing data as the comet gets closer and closer to the Sun. Whatever happens to Philae, Rosetta will stay with the comet for over a year, accompanying it as it swings around the sun and heads back out towards Jupiter.

“Arriving at the comet is really only just the beginning of an even bigger adventure, with greater challenges still to come as we learn how to operate in this uncharted environment, start to orbit, and, eventually, land,” said Sylvain Lodiot, ESA’s Rosetta spacecraft operations manager.

The Ten-legged Spider

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Every word in the title is a lie. The creature I’d like to introduce isn’t a spider and it doesn’t have ten legs, but that was exactly what I thought when I got a good look at it, which wasn’t the first time I saw it. The first time I saw it, I thought it might have been a plant’s root or some kind of stolon. I had just jumped in for a swim on Saturday afternoon when I saw something brown at the bottom of the pool. It wasn’t moving, and it seemed to be about the size of my thumb. Grabbing the sieve, I dived down and fished it out, then called my partner over. “Can you have a better look at this and see what it is? I think it’s some kind of root, but I can’t really see it properly.” My long, wet hair was obscuring my vision and I was trying to keep the sieve above water.

“It’s a spider,” she said. “A gigantic spider!” (It was gigantic — around 8-9cm across!) I’m lucky enough to be married to someone with a fascination for creepy-crawlies; with a smile, she deposited the dead spider in a jar for later examination and then joined me in the pool. Continue reading

The Bone-house Wasp

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The newly discovered Bone-house wasp, Deuteragenia ossarium, builds a unique nest for its young. Unlike species which excavate their own nests, D. ossarium belongs to a group of nest-building wasps which use existing cavities, such as abandoned galleries of wood-boring beetles, as nest sites. Female wasps abandon their nests after sealing their brood within; they don’t care for their young or offer any protection beyond what the nest provides. The nest consists of a few brood-containing cells and an outer ‘vestibular’ cell — an entryway — which probably serves as a defensive barrier. The vestibule is usually empty, but researchers surveying nests in southeast China found a surprise in some of the entry halls — they were full of ant corpses. The team reared the brood from the nests and discovered a new wasp species, which they named after the striking ossuaries found in some parts of the world.
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How Some Critters Evolved to Eat Poison

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Since plants generally can’t move around, they have to rely on other strategies to cope with animals eager to turn them into a meal. Chemical weapons are a significant part of plants’ defensive arsenal. For example, thousands of plant species produce precursors of the deadly poison hydrogen cyanide; when an animal eats the plant, the precursors get converted into cyanide, which kills the offending animal. Continue reading

Book review: We Are Our Brains

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'We Are Our Brains' by Dick SwaabI have mixed feelings about We Are Our Brains. The author, Dick Swaab, is a professor of neurobiology at Amsterdam University with decades of research experience and many awards to his name, so the book is full of fascinating and intriguing information. Unfortunately, I felt like the delivery was somewhat lacking, leaving me with more questions and wanting more information. That’s not inherently a bad thing, but I feel like the book could have done a much better job of handling some of the inevitable questions and challenges it raises — it could benefit from engaging in dialogue with the reader rather than simply making assertions. Continue reading

The give-and-take between mothers and their offspring

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Image credit: Flickr user nekrumThis is a story about a gene which makes nursing mice produce more nutritious milk while also making their offspring less demanding. The gene serves to balance nutrient supply and demand between the mother and pup. If the gene is knocked out, the mother’s milk is less rich, but the pups are more demanding, evening out the impact. Things only go wrong when there’s a mismatch. If pups with a defective copy of the gene feed from a normal mother, their increased demand makes them grow larger than normal. Conversely, pups with a good copy end up smaller if they feed from a mother lacking a working copy, since her milk is less nutritious. Continue reading