MV Blog


Dawn reaches Ceres

by Tanya Hill
Publish date
5 March 2015
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When NASA’s Dawn spacecraft is captured into orbit around the dwarf planet Ceres on Friday, March 6, there will be no fanfare in mission control. In fact, the spacecraft won’t even be in radio contact. There’s no need, because Dawn’s path is set – this is a spacecraft unlike any other.

What makes Dawn unique is its ion propulsion system, which gives the spacecraft incredible manoeuvrability. Instead of using large bursts of thrust to get where it’s going, Dawn takes the slow and steady approach. Its ion engine delivers a tiny but continuous thrust that can last for days or weeks at a time.

Over the last two-and-a-half years, Dawn has been slowly reshaping its trajectory to bring it near Ceres and, most importantly, to match the dwarf planet’s speed – Ceres travels around the sun at nearly 64,000 kilometres per hour.

For other planetary missions, entering orbit is make or break. It’s an intense moment that hopefully ends in jubilant celebration when all goes as planned and the spacecraft momentously falls into orbit. But Dawn’s slow approach means that it is now right on course to guarantee capture by Ceres’ gravity.

Dawn is captured by Ceres' gravity The spacecraft’s approach trajectory with the white circles spaced at intervals of one day. This indicates the spacecraft’s speed – the closer the circles, the more slowly Dawn is moving.
Source: NASA/JPL

Come Friday, if the spacecraft’s propulsion were to be switched off it would remain under Ceres’ influence but would travel around the dwarf planet in a highly elliptical orbit. So over the next few weeks, Dawn will use its ion thrusters, together with Ceres’ gravity, to slowly draw it into a circular orbit – the first of four such orbital positions around the dwarf planet.

Not for the first time

Ceres is the second object that Dawn has orbited. Between July 2011 and September 2012, Dawn was in orbit around Vesta, which, like Ceres, resides in the asteroid belt located between Mars and Jupiter.

This marks the first time that one spacecraft has been able to orbit two different planetary objects. And it’s only possible because of Dawn’s ion engine.

A spacecraft powered in the usual way, using chemical propellant, would require ridiculous amounts of fuel to carry out such a mission. And even if it was possible for a spacecraft to carry that much fuel on-board, the cost of the mission would be astronomical.

Dawn's path to Ceres Dawn was launched in September 2007 and has taken the slow and steady approach to visit Vesta and now Ceres.
Source: NASA/JPL

At Ceres, Dawn will eventually travel in a polar orbit, travelling above the north and south poles. As it moves from north to south it will travel over the daytime side of the planet, and then during the second half of its orbit it will fly above Ceres' night side.

In its first orbital position, at a height of 13,500km, it will take 15 days for Dawn to complete one orbit. Since the planet takes only nine hours to rotate on its axis, this will allow Dawn to make a good map of the dwarf planet’s surface.

Throughout its 15-month mission, Dawn will vary its orbit three times, each one descending closer to the planet at heights of 4,400 km, 1,470 km and 375 km. To change orbits it will move through a complex series of spiral trajectories.

The descent to its lowest orbit will take two months and, during that time, Dawn will complete 160 revolutions as it constantly reorientates itself to ensure that one of its ion beams is thrusting in the right direction to continue its slow spiral descent.

Dawn's spiral descent Two months of downward spirals are needed to move Dawn into its lowest orbit - from the High Altitude Mapping Orbit (HAMO) to the Low Altitude Mapping Orbit (LAMO).
Source: NASA/JPL

Better than Star Wars

Ion propulsion systems, like the one that powers the Dawn spacecraft, have long been considered the next big thing for space exploration. In fact, they seemed so futuristic that they appeared in the Star Wars movies, powering Darth Vader’s TIE fighters or Twin Ion Engine fighters.

Science fiction to science fact The TIE fighters in Star Wars had twin ion engines, but Dawn does one better, with three ion engines.
Source: NASA/JPL

Ion engines were first used by NASA on Deep Space 1, which flew past the asteroid 9969 Braille in 1999 and comet Borrelly in 2001.

The Japanese Aerospace Exploration Agency (JAXA) has successfully used ion engines on its Hayabusa asteroid missions, the second of which was launched in December last year.

The Dawn spacecraft is fitted with three ion engines, although only one engine is used at any one time. And true to what we expect from science fiction, the spacecraft does emit a blue-green glow. This is a result of its xenon fuel.

The inner workings of an ion propulsion system. The inner workings of an ion propulsion system.
Source: NASA

Positively-charged xenon ions pass through two electrically charged grids. This accelerates the tiny ions and they shoot out of the engine at 144,000 kilometres per hour, providing the thrust to propel the spacecraft in the opposite direction.

Ion engines are around ten times more efficient than chemical rockets because the ions are ejected at roughly ten times the speed that a propellant is expelled by a rocket. The acceleration, however, is much slower.

It would take Dawn around four days to accelerate from 0 to 100 kilometres per hour but the trade off is that in doing so, it would only use 450grams (or just one pound) of fuel.

Why Vesta and Ceres?

Of course, the reason the technology is so marvellous is because it enables such fantastic science – the exploration of the two most massive objects in the asteroid belt, Ceres and Vesta.

The dwarf planet Ceres New images of Ceres, taken February 19 at a distance of 46,000km, show a mysterious double bright spot.

Don’t let their location fool you – these are not space rocks like typical asteroids. They are big worlds and, like Earth and the other terrestrial planets, Ceres and Vesta have a layered structure.

Vesta has an iron-rich core, a silicate mantle and a crust made of basalt. While Ceres is thought to have a rocky core, an ice mantle and a dusty surface.

The ice mantle is particularly interesting. It’s thought that around 30% of Ceres’ mass may come from water and potentially some fraction of that could be liquid water. Just last year, the Herschel Space Observatory made detections of what appear to be plumes of water vapour escaping from slightly warmer regions on Ceres.

The Dawn mission will continue until June 2016 and the latest images will be regularly posted here, while the Dawn mission blog is a great way to keep up-to-date on everything that happens.

Dawn of the Solar System

The space mission was called Dawn because if we think of Ceres and Vesta as protoplanets, then by better understanding these objects, we will gain insight into the early history of our solar system.

Vesta and Ceres size comparisons Ceres and Vesta more closely reflect half-formed planets than space rocks like asteroids.
Source: NASA

The planets of our solar system formed by a method of accretion. Starting out as specks of dust that collided and stuck together, they then grew bigger and formed rocks until eventually they were large enough to draw in enough material to form planets.

Vesta and Ceres seemed to have halted mid-way through this process. This is most likely due to the formation of Jupiter. Its gravity may have prevented objects in the asteroid belt from coming together to finish off the planet building.

As a result, Vesta and Ceres provide a unique opportunity for understanding the early formation of the planets, because they came so close to becoming planets themselves.

The early solar system The early solar system was born out of a dusty disc encircling the sun.
Source: William Hartmann. Courtesy of UCLA

The ConversationThis article was originally published on The Conversation. Read the original article.

MV's new digital exhibits

by Nicole K
Publish date
5 March 2015
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On Tuesday 3 March, Museum Victoria joined 25 Australian cultural institutions at Parliament House to launch the Australian component of the Google Cultural Institute.

Google Cultural Institute launch, 3 March 2015, Parliament House, Canberra Google Cultural Institute launch, 3 March 2015, Parliament House, Canberra
Image: Nicole Kearney
Source: Museum Victoria

The Google Cultural Institute is an online collection of millions of cultural treasures from over 670 museums, art galleries and archives around the world. Visitors can explore millions of artworks and artefacts in extraordinary detail, create their own galleries and share their favourite works.

Museum Victoria has been involved in the Google Art project since 2011 and was among the first institutions to partner with Google to create what is now the world's largest online museum.

Featured content on the Google Cultural Institute Featured content on the Google Cultural Institute
Source: Google

Tuesday's launch welcomed 14 new Australian contributors, including the Australian War Memorial, the National Portrait Gallery and the Australian Centre for the Moving Image. Over 2000 of Australia's finest cultural works are now accessible online.

Among these treasures are 226 highlights from Museum Victoria's collection. These include Aboriginal bark paintings, photographs depicting early Victorian history, and scientific illustrations that trace the development of scientific art.

In order to tell the fascinating stories behind these collection items, we have created three digital exhibitions within the Google Cultural Institute:

The Art of Science: from Rumphius to Gould (1700-1850)

The Art of Science exhibit The Art of Science exhibit
Source: Museum Victoria

Scientific Art in Victoria (1850-1900)

Scientific Art in Victoria exhibit Scientific Art in Victoria exhibit
Source: Museum Victoria

A.J. Campbell (1880-1930)

A.J. Campbell exhibit A.J. Campbell exhibit
Source: Museum Victoria

These exhibits include stunning photographs and illustrations, curator-narrated videos and in-depth information.

Many of these illustrations come from rare books preserved in our library and, in many cases, accompany the first published descriptions of our unique Australian fauna. The books are available online in their entirety in the Biodiversity Heritage Library, a project funded in Australia by the Atlas of Living Australia.

Predator vs predator

by Patrick
Publish date
9 February 2015
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Museum Victoria Bioscans and other biodiversity surveys tend to focus on the bigger and more spectacular Victorian animals, such as Gippsland Water Dragons and Wedge-tailed Eagles, but some of the most interesting stories come from the little creatures. 

Spider wasp nest A partially opened nest of a spider wasp (Fabriogenia sp.). The spider prey in two of the cells have been replaced with wasp pupae.
Image: Patrick Honan
Source: Museum Victoria

One such highlight of the recent Gippsland Lakes Bioscan was a mud nest of a spider wasp (Fabriogenia sp.). The nest comprised six cells, each built to house a Mountain Huntsman (Isopeda montana). The cells are made from dried mud, probably mixed with eucalyptus resin to harden them. The female wasp takes about one day to construct each cell, then heads off to find a live huntsman and undertakes a life-or-death battle. Upon seeing an approaching spider wasp, a huntsman’s behaviour—excuse the anthropomorphism—is best described as a ‘mad panic’.

black wasp Adult female spider wasp, Fabriogenia sp.
Image: Patrick Honan
Source: Museum Victoria

The wasp is swift and deadly accurate, stinging the huntsman to immobilise it, then removing each of its legs at the first joint. She carries the spider back to her nest, lays an egg on its defenceless body, then seals it in. The egg hatches into a fat wasp grub, feeding on the internal juices of the spider until nothing but a shrivelled husk remains. The grub then forms a pupa and eventually emerges from its cell as an adult wasp, ready to continue the cycle.

Huntsman spider with no legs A dismembered huntsman removed from the mud nest. The pedipalps remain intact and the fangs are in working order.
Image: Patrick Honan
Source: Museum Victoria
Most members of this wasp family, the Pompilidae, leave the spider intact and paralyse it permanently. In this case, not only does the wasp cut off its prey’s legs, but the venom seems to immobilise the huntsman only temporarily and the spider wakes up after the cell is sealed. 


On a personal note, having handled spiders for more than 30 years and never being bitten, one of the spiders latched on to my finger while I was examining the nest. Like most huntsman bites there were no symptoms other than a sharp nip, and given its situation I couldn’t really blame it.

Spider wasp, spider, and spider-wasp mimicking beetle Left: Another member of the Pompilidae, the Zebra Spider Wasp (Turneromyia sp.) battles a huntsman on a gum tree in Royal Park, Melbourne. | Right: Wasp-mimicking Beetle (Trogodendron fasciculatum), also photographed in Royal Park, Melbourne.
Image: Patrick Honan
Source: Patrick Honan

And as a side note, spider wasps are ferocious enough to have their own mimics. The Wasp-mimicking Beetle (Trogodendron fasciculatum) looks roughly like a spider wasp, with its black and white body and orange antennae, but its behaviour is almost identical. Moving rapidly over tree trunks with twitching antennae it would, at least, be safe from roaming huntsmans.

Love is in the air

by Blaire Dobiecki
Publish date
2 February 2015
Comments (1)

Blaire is a Presenter at Melbourne Museum and self-professed dog enthusiast. She specialises in having fun and doing science, often simultaneously.

My opening question when presenting education programs to eager students is 'what’s the best thing you’ve seen today?' The range of answers always astounds me. From the Mamenchisaurus to the Marn Grook, sometimes kids name things that I didn’t even know we had. 

Museum love letter from Tui A love letter from visitor Tui reads 'Dear Dinosaurs, I love your big bones and srong teeth. You are soooo cool. Love Tui'
Source: Museum Victoria

Inspired by their answers, I’ve helped develop a weekend program called Museum Love Letters. From 31 January to 22 March, we invite everyone and anyone to write a love letter to their favourite museum object.

Museum love letter from Christine Love letter from Christine reads 'Dear pretty, groovy Luna Park roller coaster carriage, You make me happy just by still existing! Christine xo'
Source: Museum Victoria

Perhaps you’d like to tell Phar Lap that you remember visiting him as a child? Maybe you find the Federation Tapestry particularly touching? Is it time to tell the crystalline gypsum how beautiful it is? Now’s your chance!

Visit Melbourne Museum on a weekend to write your message on heart-shaped cards and post them in our special love letter mailbox. Otherwise, post your letter to:

Museum Love Letters
Melbourne Museum
GPO Box 666
Melbourne VIC 3001

Outpourings of love from staff are already rolling in. Here’s part of the letter from Caz in our Humanities department, to Phar Lap:

Love letter to Phar Lap Caz's letter reads, 'I remember the time I walked past your glass stable in the old Swanston Walk Museum, to discover that an anonymous fan had left you some crepe paper carrots on your birthday. Now that is true love!'
Source: Museum Victoria

Megan, one of our volunteers, has written to an entire exhibition!

Love letter to Bugs Alive Megan's Ode to Bugs Alive! reads, 'Oh Bugs Alive! I love you so, with your shiny wings + feet. With your hairy, shedding carapaces, you're a creepy, knobbly treat.'
Source: Museum Victoria

We will be keeping track of which objects receive letters of love and we’ll update you with the results throughout the program. Don’t forget to share your love letters with us on social media using the hashtag #MelbourneMuseum.

We look forward to reading your letters. There are rumours that the objects themselves may write back! 

Vale Bill Woodward

by Charlotte Smith
Publish date
23 January 2015
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Dr Charlotte Smith is MV's Senior Curator, Politics and Society.

This week, Museum Victoria volunteer Bill Woodward lost his fight with cancer. Bill was the quintessential quiet achiever; for almost 24 years he spent every Wednesday morning researching, cataloguing and filing documents relating to the history of the Royal Exhibition Building (REB).

Bill Woodward Bill Woodward next to Ivy Raadik. The photo was taken under the dome of the REB in 1996, at an REB Museum Volunteers dinner.
Source: Museum Victoria

It was around 1991 that Bill first began working on the ‘REB Museum’ project. At this time, the REB was managed by a government-appointed body of Trustees. While responsible for ensuring the financial viability of the REB’s event and conference business, the Trustees also recognised the need to document the building’s past. In 1988 the Trustees appointed museum professional Nina Stanton to develop a collection and archive. Nina’s call for volunteers in September 1990 attracted over 65 applicants. Not all made it through the intensive interview process!

Bill joined the team about a year later. Each team member had a role: some spent their days researching at the Public Record Office or State Library, another spent her time developing a chronological list of events, while others traced the history of pictures exhibited at Melbourne’s two International Exhibitions. Bill’s role at this time was to key all the information gathered by fellow volunteers into the computer. Other members of the team then filed the documents and images into filing cabinets.

In 1996, custodianship of the REB was transferred to Museum Victoria. As part of the transfer, the museum acquired a significant collection of objects, a growing archive, and a team of amazing volunteers.

Bill Woodward and woman Bill chatting with a fellow volunteer at a casual gathering in the REB, early 1990s.
Source: Museum Victoria

I joined the museum as Senior Curator responsible for the REB collections in 2007. At this time, the REB volunteer team had shrunk to two regulars: Deidre Barnett and Bill Woodward. Deidre retired at the end of 2008, so it was just Bill and I who used to get-together early on Wednesday mornings for a chat.

My first indication that Bill was not completely well was about four years ago, but in typical Bill style he refused to give in to his illness. Every Wednesday morning he would be at his desk, typing away with research he had done at the State Library. There were weeks when he’d go off for treatment, but he’d always return with enthusiasm and a wide smile.

Bill died surrounded by his family. His wife tells us he had a smile on his face; a wonderful and evocative image for those of us who knew Bill well. Many of us in the Humanities Department will miss Bill immensely; I will definitely miss my Wednesday morning chats, but find solace in the knowledge that Bill’s legacy will live on in the amazing archive he spent a quarter of a century developing.

Desperately Seeking Graham

by Nick Crotty
Publish date
19 January 2015
Comments (2)

Nick is a Collections Manager at Scienceworks. He likes piña coladas, walks in the rain, Star Wars and hiding away from the light.

This radio recently came off display in The Melbourne Story. I was returning it to storage when I noticed that a conservator had bagged a small piece of paper while cleaning the radio in 2008, and had suggested that it be kept with the object. 

Radio from 1933 Broadcast Receiver (radio) made by Astor. This is the Mickey Mouse, model circa 1933 (ST 028290).
Image: Nick Crotty
Source: Museum Victoria

This torn slip of paper was not originally part of the radio, but tightly rolled and inserted inside a small hole on the side.

Side of old radio The side of the radio showing the hole with a piece of paper rolled inside.
Image: Rebecca Dallwitz
Source: Museum Victoria

On one side of the paper was typed 'TAKE A PAIR OF SPARKLING EYE...' (the paper was torn here), and on the other, was beautifully handwritten in pen 'I put on the paper “Do you like Graham” and she said “Of course I do”!!!'

Detail of hand-written note The two sides of the note found inside the radio.
Image: Nick Crotty
Source: Museum Victoria

Well, this is interesting! Immediately I started wondering; who wrote the note? And why did they place it inside the radio? Were they trying to hide it, or save it for reading later? Or were they just using it to stop excess noise coming out of the radio (or bugs getting in?!). 

Who is the 'she'? Who was 'Graham'? His name was written with the H underlined three times. Was there another Graeme without an H? What made Graham special? Did it refer to Graham Kennedy? He was on the radio in the early 1950s and on In Melbourne Tonight from 1957 to 1970.

Graham Kennedy A signed photo of Melbourne television personality Graham Kennedy in 1957, sitting on the set of his live variety program In Melbourne Tonight which was filmed at the studios of GTV Channel 9 in Richmond, Victoria.
Image: Athol Shmith
Source: Museum Victoria

Was there meaning behind the typed piece of paper? A quick google search of the words brought up a Gilbert & Sullivan song called Take a Pair of Sparkling Eyes from the operetta The Gondoliers. It’s a song sung in Act 2 by Marco Palmieri, a Venetian Gondolier, and is described by one critic as 'the most saccharine and chauvinistic ditty' of the Gilbert & Sullivan canon.

Two men in costume Rutland Barrington and Courtice Pounds as Marco and Giuseppe from the 1889 original production of The Gondoliers.
Source: The Gilbert and Sullivan Archive

Then I thought, was this a note passed in class? I wonder if school kids still do, or do they just text each other now? Of course this note was about another note ('I put on the paper'). Is this an old fashioned version of forwarding? Has anyone done anthropological research into the act of childhood note-passing during class?

I thought perhaps the source of this object might provide some clues. It was bought for the collection on 25 February 1972 from the Salvation Army Op Shop in Abbotsford, presumably by a curator. Our collection database says that during early January and February 1972, eight electronic valves were also purchased from the same shop.

Normally the museum acquires objects with a good provenance or story as that helps form exhibitions and captures the imagination of visitors. Sometimes, particularly in the Technology collections, we collect objects because of the part they played in technological development, especially if they are in good condition. The famous Astor Mickey Mouse was the biggest-selling radio in Australia during the 1930s.

Unfortunately I have reached a dead end. It might just be one of those mysteries that will never be solved. Nevertheless, the story of what could have happened has piqued my interest for a few days.

If you or a family member donated an old radio to the Abbotsford Salvation Army Op Shop in the early 1970s and knew a friend that had a liaison with someone called Graham (with an H) please leave a comment. I’d love to hear the full tale, especially if there is a happily ever after.

About this blog

Updates on what's happening at Melbourne Museum, the Immigration Museum, Scienceworks, the Royal Exhibition Building, and beyond.