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DISPLAYING POSTS FROM: Feb 2013 (10)

Asteroid zooms by Earth

Author
by Tanya
Publish date
11 February 2013
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Most of the time we rush through space without giving it a second thought. But every now and again the Universe reminds us that we are not alone.

On Saturday morning, 16 February, Earth will be buzzed by asteroid ‘2012 DA14’. Its closest approach at 6:25am, will bring it 34,000km from Earth. That’s just a little closer than the geosynchronous satellites – a ring of communication and weather satellites that orbit the Earth at 36,000km. Earlier predictions had the asteroid coming even closer, but Earth’s gravity keeps tugging on the asteroid and changing its predicted path, ever so slightly.

Flight path of asteroid 2012 DA14 The path of asteroid 2012 DA14, which approaches Earth from "below" and passes through the ring of geosychronous satellites. The times given are AEDT.
Source: NASA/JPL-Caltech
 

One thing is quite clear – there is no chance the asteroid will collide with Earth and that’s a good thing. At 45 metres across, it’s not particularly small and probably of similar size to the asteroid that exploded over Siberia in 1908. Known as the Tunguska event, it flattened 80 million trees across an area the size of Port Phillip Bay.

Path of asteroid 2012 DA14 from Melbourne The path of asteroid 2012 DA14 across the south-west sky as seen from Melbourne on the morning of Saturday 16 February 2013. The times indicated are in AEDT while the positions with relation to the horizon are calculated for 5:25am.
Source: Melbourne Planetarium
 

Asteroid 2012 DA14 won’t be bright enough for us to see, but experienced observers could catch a glimpse with a small telescope. It will appear in the south-west, just below the Southern Cross – the hard thing will be pin-pointing it while it’s zipping along at 28,000 km/hour.

The rock was discovered almost a year ago by the La Sagra Observatory in southern Spain. It’s one of a handful of observatories that hunt and monitor Near Earth Objects. Each day, about a hundred tons of interplanetary material falls onto Earth – mostly dust from comets or small fragments from asteroid collisions. But once every 100 years, we expect something larger, like 2012 DA14, to appear. It’s nice to know there are people out there looking and making sure our path is clear.

Trees felled by the Tunguska explosion. The Tunguska event was caused by a similar sized asteroid exploding over Siberia in 1908.
Source: the Leonid Kulik Expedition
 

Links:

A Ustream feed of the flyby from a telescope at NASA's Marshall Space Flight Center in Alabama, will be broadcast from 1pm to 4pm, 16 February (AEDT).

Animations and interviews by NASA scientists

Accounts of the Tunguska event from Science at NASA

MV scientists head back to Sulawesi

Author
by Kevin Rowe
Publish date
7 February 2013
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Kevin is our Senior Curator of Mammals. He investigates the systematics, evolution and conservation biology of mammals with a particular interest in rodents.

I'm about to depart on the next expedition to the high mountains of Sulawesi along with MV Ornithology Fellow Karen Rowe, and MV Collection Manager of Terrestrial Vertebrates Wayne Longmore. We'll be surveying birds, rodents, bats and shrews, in areas virtually unknown to science.

Anang Achmadi Kevin Rowe in montane forest on the island of Sulawesi.
Image: Kevin Rowe
Source: Museum Victoria

Karen Rowe Karen Rowe conducting fieldwork in lower montane forest on the island of Sulawesi.
Image: Peter Smissen
Source: Museum Victoria

Wayne Longmore N. Wayne Longmore with a Sulawesi Kingfisher (Ceyx fallax) in lowland rainforest.
Image: Kevin Rowe
Source: Museum Victoria
 

An evolutionary cross-roads between Australia and Asia, the Indonesian island of Sulawesi is home to mostly endemic species (those found nowhere else) and its mix of dense equatorial rainforest and mountain peaks of some 3,000 metres lends a profusion of life rarely seen worldwide.

Our primary target on the coming expedition is Mount Sojol on Sulawesi's northern peninsula. We know from observational bird surveys that vertebrate diversity is probably quite high, but there have been virtually no specimens collected from this part of Indonesia. Like many mountains on Sulawesi, only the local people really know what is there.

However, before we can start any surveys there's a lot to do. This week the team is packing equipment and supplies needed to collect and preserve specimens. On Saturday, I fly to Jakarta.

I'll spend my first week in Indonesia completing visa and permit paperwork with visits to several government offices. Between paperwork, I will prepare supplies and examine specimens with collaborators at Museum Zoologicum Bogoriense (the national zoological museum of Indonesia).

Once the paperwork is complete, I will fly to Palu, Sulawesi and will travel 200 km up the Trans-Sulawesi Highway to the village of Siboa. From Siboa, my collaborators and I will meet with local people including the village head, or kepala desa, to obtain their support and approval. With the help of local guides we will hike into the mountains where we will spend a week searching for suitable field camps. Karen, Wayne, and other collaborators from the USA will meet me in Palu after a week of completing their own paperwork in Jakarta. They will make the trek into the forest camp and begin the process of surveying the unique birds and mammals of Mount Sojol, Sulawesi.

In the sixth week, we will all return to Palu to share the results of the inventory with the Indonesian Department of Forestry before flying back to Jakarta. There we'll spend a final week packing specimens and obtaining permits to export the specimens to Australia where they will join the state collection at Museum Victoria.

The Sulawesi research trip is part of a multi-year project supported by the National Geographic Society, the Australian Pacific Science Foundation, the Ian Potter Foundation and the Hugh D T Williamson Foundation that includes key research partners Museum Victoria, the Museum Zoologicum Bogoriense (National Museum of Indonesia), the Field Museum of Natural History, the Museum of Vertebrate Zoology at the University of California, Berkeley, and McMaster University. The multi-national team comprises Canadian, American, Australian and Indonesian researchers.

The team's announcement that they had discovered a remarkable new rodent genus – an almost toothless, worm-eating rat, Paucidentomys vermidax – made international headlines last year.

Paucidentomys vermidax New genus and species, Paucidentomys vermidax
Image: Kevin Rowe
Source: Museum Victoria

Skull of P. vermidax Skull of new genus and species, Paucidentomys vermidax, the first rodent discovered with no molars.
Image: David Paul
Source: Museum Victoria
  

Bug of the Month - the mosquito

Author
by Tim Blackburn
Publish date
4 February 2013
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Mosquitoes are midge-like flies comprising the family Cucilidae. There are over 3,500 species of mosquito described worldwide and most of these require vertebrate blood as the principal portion of the female diet. The blood provides protein for egg development and maturation, and the lipids it contains are an energy source. Females possess elongated piercing and sucking mouthparts for obtaining their blood meals. Males obtain all their energy from sweet fluids such as nectar and honeydew. Since they don't lay eggs, male mosquitoes do not require a protein source and do not bite.

Close-up of female mosquito The elongated proboscis of this female mosquito enables it to obtain the protein it requires for egg development and maturation.
Image: sondebueu
Source: sondebueu via cc
 

Adult females lay eggs in or near water, commonly on vegetation, a few days after a blood meal. The life cycle includes four larval stages, or instars. Between each instar the larva moults in order to grow. The larvae, or 'wrigglers' (so-called due to their characteristic movement), typically inhabit stagnant water bodies, and must come to the surface periodically to breathe through spiracles or a siphon. The larvae of some species use their mouth bristles to filter water for microorganisms, while others scrape food particles off the surfaces of submerged objects. The pupa does not feed but must come to the surface to breathe through respiratory trumpets.

mosquito larva The mouth bristles, used in filter feeding, are clearly visible on this wriggler. Note also the three body segments and the segmented abdomen.
Image: Tim Blackburn
Source: Museum Victoria
 

Female mosquitoes inject saliva that contains an anticoagulant into their host to prevent blood-clotting. The saliva also contains components that cause vasodilation (to increase blood blow) and suppress the immune response of the host (to protect the mosquito). Once the feeding episode ends, the host produces antibodies which trigger a release of histamine. This in turn increases the permeability of adjacent blood vessels, thereby enabling a stronger immune response. The blood vessels swell and this causes the familiar, itchy lump—the 'mozzie bite'.

Female mosquito A female mosquito just after landing on my toe as it commences a blood meal. Note the thin abdomen at the start of the meal.
Image: Tim Blackburn
Source: Museum Victoria
 

Female mosquito feeding The same mosquito one minute later. Note the swollen abdomen which is red because it is full of my blood.
Image: Tim Blackburn
Source: Museum Victoria
 

Viruses and pathogens are easily transferred between mosquito and host via the saliva. Mosquitoes are serious agents in the transmission of diseases such as dengue and yellow fever, malaria and lymphatic filariasis. In 1996, the World Health Organisation estimated that several million people die each year from mosquito-borne diseases around the world. Each disease is spread by a specific type of mosquito; malaria is spread by Anopheles spp. and dengue fever is primarily spread by Aedes aegypti.

However, mosquito-borne diseases are rare in Victoria, and mosquitoes here are more likely to annoy rather than cause disease. You can prevent bites by wearing insect repellent and protective clothing, and removing breeding sites. Window mesh and mosquito nets also help exclude potentially harmful species, particularly in tropical and subtropical areas. Various plant species such as Citronella Grass, Rosemary, Catnip and Marigolds repel mosquitoes and may be especially useful if planted near doorways and windows. 

Links:

CDC: Mosquito-borne diseases

Vector-borne diseases in Victoria

Space Shuttle Columbia

Author
by Tanya
Publish date
1 February 2013
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It was 10 years ago today, 1 February 2003, that the Space Shuttle Columbia broke apart on its way back to Earth. The STS-107 crew had spent 16 days in orbit and were just 16 minutes from landing when the accident tragically occurred.

Crew of STS-107 This photograph survived on a roll of unprocessed film recovered from the accident. Bottom row (L to R): Kalpana Chawla, mission specialist; Rick D. Husband, mission commander; Laurel B. Clark, mission specialist, and Ilan Ramon, payload specialist. Top row (L to R): David M. Brown, mission specialist; William C. McCool, pilot, and Michael P. Anderson, payload commander.
Source: NASA
 

On a trip to the USA in 2002, I attended a talk by astronaut and astronomer, John Grunsfeld. He was asked “why fly into space when the risks are so high?” and his reply has always stuck with me. It was pretty much “because it’s the most amazing thing to do.

He went on to explain that while astronauts are fully aware of the risks involved – and they don't take them lightly – they are also certain that the benefits of what they are doing will lead to greater things for our future.

Today we remember the amazing men and women who have believed in the spirit of space exploration. I hope there will always be pioneers just like them, who are willing to push the limits of what’s possible and dream big for all of us.

Links:

Powerhouse Museum: "Sometimes, when we reach for the stars, we fall short..."

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