Where does our Galaxy get the fuel to keep forming stars? The answer may lie in thousands of gas clouds flying around the outskirts of our Galaxy.
Originally posted on Universe @ CSIRO:
“Food pills” were a staple of science fiction for decades. For our Galaxy, they may be real.
The Galaxy has been making stars for the last 8 billion years. What’s kept it going all that time?
Some exciting news from ‘The Dish’ today.
Originally posted on Universe @ CSIRO:
In the journal Science today, astronomers using our Parkes telescope have revealed signs of cataclysms in the distant Universe.
They’ve found four ‘bursts’ or ‘flashes’ of radio waves, the furthest one coming from about 11 billion light-years away. And, they say, if you had ‘radio eyes’ — eyes that could detect radio waves — you’d see one of these ‘bursts’ going off somewhere in the sky every ten seconds. It would be like a continuous show of distant fireworks.
If you thought ISS Commander Chris Hadfield’s micro gravity rendition of Space Oddity was the hit of the week, think again.
The latest album from electro music duo Daft Punk is being launched in Wee Waa this week and we’re ready to get down. It was reported that the French duo chose Wee Waa, in regional NSW, because of its proximity to our Australia Telescope. The global album launch will include a party at the Wee Waa show on Friday night.
The Australia Telescope Compact Array is so ready that it’s been getting down to Daft Punk’s Get Lucky.
Our researchers are getting into the swing of things too, giving a tour of the telescope operating room in signature Daft Punk helmets.
And finally, researchers dancing.
Meet Giovanna Zanardo: a PhD student at the International Centre for Radio Astronomy Research who’s using our telescopes to study the remains of a star that exploded in 1987.
Called Supernova 1987A, the explosion made astronomers super excited, because it was the first naked-eye supernova to occur since optical telescopes were invented four centuries ago.
Giovanna has been using the Australia Telescope Compact Array - a set of six dishes near Narrabri, NSW – to study the aftermath of the exploded star. And this month she’s going to be using our iconic Parkes telescope to look at it again.
While at Parkes, Giovanna and fellow scientists will be looking to see if a pulsar – a compact spinning star packed with neutrons – has been created after the collapse of the star’s core, which drove the stellar explosion.
“My PhD in astronomy has been a fantastic journey. I’ve got a front row seat to watch the evolution of a truly amazing object and the chance to use all of Australia’s radio telescopes.”
Giovanna began her career as a structural engineer in Western Australia, but after hearing plans to build the Square Kilometre Array (SKA), she saw this as an opportunity to get into radio astronomy.
From the moment she had a glimpse at the early radio images of Supernova 1987A, Giovanna was hooked. And she’s never looked back.
“I became an engineer because I love structures – but I’ve always loved physics and astronomy. My work allows me to combine the two by investigating large structures in space and seeing how they impact and interact with the surrounding environment,” says Giovanna.
To learn more about careers with us, head to our LinkedIn page.
Tomorrow is ANZAC Day, and some of you will be getting up to go to dawn services.
What is the dawn, anyway? Sure, it’s when the Sun comes up, but did you know there’s a difference between dawn and sunrise?
Sunrise: not what it seems
Sunrise is the moment when the edge of the Sun seems to peep over the horizon. “Seems”, because the Sun hasn’t actually reached the horizon yet: in fact, its image is refracted — the light rays are bent — by the Earth’s atmosphere. The average amount of refraction is 34 arcminutes (an arcminute is a sixtieth of a degree); however, it varies, depending on atmospheric conditions. (Thirty-four arcminutes is quite a lot: if you stand 100 m away from a target, 34 arcminutes is the angular distance between the bullseye and a point one metre off to the side of it.)
On top of that, the Sun isn’t just a point of light, but an extended source, a disk about 16 arcminutes in radius.
The combination of these two factors means that sunrise actually occurs when the Sun’s centre is 50 arcminutes, or almost one degree, below the horizon.
Dawn, on the other hand, is the beginning of morning twilight — the time when the sky begins to lighten, well before the Sun shows its face.
Astronomers, sailors and ordinary folk have different kinds of dawn.
Astronomers — optical astronomers, anyway — like things to be really dark. For them, dawn occurs when the middle of the Sun’s disk lies 18 degrees below the horizon in the morning.
Nautical dawn takes place when the Sun is 12 degrees below the horizon, while civil dawn occurs when it is just six degrees below the horizon.
The Earth’s shadow
Shortly before sunrise, if you look in the opposite direction to the Sun (i.e. to the west), you may see a dark blue or greyish-blue band in the sky. This is the shadow that the Earth itself casts on its lower atmosphere. The pink band that appears above it is called the Belt of Venus: it is the Earth’s upper atmosphere, illuminated by the Sun’s rays. Both the shadow and the Belt can be seen at sunrise or sunset.
“And tomorrow the sun will shine again”*
Dawn is synonymous with hope. For Christians, Easter morning marks the resurrection of Christ. At the Neolithic tomb of Newgrange in Ireland, when the Sun rises on the winter solstice its rays pass straight into the heart of the mound: we cannot know exactly what this meant to the tomb’s builders, but they went to a great deal of trouble to make it happen.
If you’re never up early enough to see the dawn, don’t despair: here’s a nice video of sunrises in South Australia to remind you of what it’s all about.
Source: YouTube . Posted by VK5SW.
* The English translation of the first line of a beautiful song, “Morgen”, by German composer Richard Strauss.
By John Sarkissian
About the author
John is an Operations Scientist at the CSIRO Parkes Radio Observatory. His main responsibilities are operations and systems development, and the support of visiting astronomers with their observations. John is a member of the Parkes Pulsar Timing Array team that is endeavouring to use precision pulsar timing to make the first direct detection of gravitational waves. In 1998–99 he acted as a technical advisor for the film The Dish. John has received two NASA Group Achievement Awards and, in 2010, received an official NASA commendation for his search for the missing Apollo 11 tapes.
UPDATE: They have found the engines. How hard can it be to find some video tapes!
It was one giant leap for mankind and it was taken at 12:56 PM (AEST) on 21 July 1969. Six hundred million people, one sixth of mankind at the time, witnessed the Apollo 11 moonwalk live on television.
As a six-year-old school boy, I was one of those millions. Sitting cross-legged on the floor of the school assembly room with my fellow first graders, we watched the events unfold on a small black and white television screen perched at the front of the assembly room. We were spellbound by the dark, fuzzy images flickering on the screen. How did they do it? How did those pictures get from the Moon to my Sydney school? Why were the pictures so dark and ghostly looking?
Little did I know then, but three decades later I would find myself working at the CSIRO Parkes Observatory, at the very place those images were received and that I would have the opportunity to answer those childhood questions. This article is a personal account of my research into the Parkes support of Apollo 11 and how it eventually morphed into a search for the missing Apollo 11 tapes. It’s been a roller-coaster ride, with many highs and lows plus a few twists and turns to make it interesting. Along the way, I’ve met many fine and dedicated people, some of whom are now close friends. This is our story.
At 12:54 PM (AEST) Buzz Aldrin switched on the lunar module camera that would transmit the TV pictures of Armstrong descending the lunar module ladder. Three tracking stations received the signals simultaneously. They were the 64-metre Goldstone antenna in California, the 26-metre antenna at Honeysuckle Creek near Canberra and the CSIRO 64-metre dish at Parkes. The signals were relayed to Houston, where a controller selected what he thought were the best pictures for release to the US television networks and distribution to a worldwide audience.
In the first few minutes of the broadcast, Houston alternated between its two stations at Goldstone and Honeysuckle Creek, searching for the best quality pictures. When they finally switched to Parkes, the pictures were so much better that they stayed with Parkes for the remainder of the 2½ hour moonwalk. From an analysis of the videotapes of the Extra Vehicular Activity (EVA) and of a recording of the NASA NET 2 communications loop (which controlled the TV reception), the timings for the TV switches are shown below.
Time (mm:ss) Video Transmission
00:00 TV on (upside down) Picture is from Goldstone (GDS). Time is 02:54:00 (GMT)
00:27 Picture is inverted and is now the right way up. Very dark, high contrast image
01:39 Houston TV switches to Honeysuckle Creek (HSK)
02:20 Armstrong steps onto the Moon. The time is 02:56:20 (GMT)
04:42 Houston TV switches back to GDS. Picture is negative
05:36 Houston TV switches back to HSK
06:49 Houston TV switched back to GDS. Picture is positive again but still dark
08:51 Houston TV switches to Parkes (PKS). Remains with Parkes for the remainder of the 2½ hour lunar EVA
From these timings, and other evidence, it is clear that at the start of the EVA, Goldstone was experiencing problems with its TV, resulting in high contrast, dark images. The Honeysuckle Creek pictures were better but they suffered from a lower signal- to-noise ratio, thus resulting in grainier images. The pictures from Parkes were the best of the three and it was these that NASA broadcast for the majority of the lunar EVA.
Television from the Moon
The Apollo Lunar Surface Camera was developed by Westinghouse and was a technological marvel of its time. The lunar module was power and bandwidth limited, so it was not possible to transmit commercial standard TV directly from the Moon. Instead, a slow-scan TV (SSTV) system was used that required less power and bandwidth. The SSTV system transmitted b/w pictures at 10 frames-per-second with only 320 lines-per-frame. In order to broadcast this to the watching world, it had to be scan-converted on Earth to commercial TV standards. An RCA scan-converter was used that operated on an optical conversion principle. It was a simple system that worked well on previous Apollo missions. Essentially, as each single SSTV frame was received on Earth, it was displayed on a small 10-inch b/w slowscan monitor. A Vidicon camera was pointed at the screen and imaged the frame at the standard commercial TV frame rate. It was the output of this camera that was broadcast to the world. In this way, a 30 frames-per-second, 525 lines-per-frame, TV picture was achieved. As you can imagine, it’s not an ideal method of scan-converting the pictures but it seemed adequate at the time.
The Goldstone TV was scan-converted on site and relayed directly to Houston via microwave relays and landline. The Honeysuckle Creek TV was scan-converted on site also, and relayed to the Overseas Telecommunications Commission (OTC) Paddington terminal in Sydney, referred to as ‘Sydney Video’. Meanwhile, the Parkes baseband signals were relayed to Sydney Video, where the TV was separated from the telemetry stream and scan-converted there.
At Sydney Video, a NASA controller would select the best of the Honeysuckle Creek or Parkes pictures, and pass that selection on to Houston. His selection would simultaneously be recorded on to 2-inch videotape on an Ampex VR660 recorder. The selected TV would be sent via microwave relays to the Moree Earth Station in northern NSW, then via the Intelsat III geostationary satellite to the United States and then finally along the AT&T landlines to Houston. At Houston, the controller would select the best of the Goldstone or Australian feeds for worldwide distribution. In a further twist, the Australian selection at Paddington was split and sent to the ABC Gore Hill studios for distribution to Australian networks. Consequently, the Australian TV did not have to travel via satellite to the US and back again. This meant that a transmission delay was not present, so Australian audiences watched the moonwalk 300 milliseconds before the rest of the world!
It is clear that scan-converting the SSTV and relaying it to the world was not an ideal situation. Firstly, the picture being displayed on the scan-converter monitor had to be adjusted manually. This was a subjective exercise, as the scan-converter operator had to adjust the brightness and contrast settings to what he thought produced the best looking picture. Unfortunately, the operator at Goldstone was inexperienced, and with the pressure of the moment, he got it wrong. At Sydney Video, the operator, Elmer Fredd, was vastly more experienced. He had helped design the scan-converter and knew it well. In December 1968, he had converted the TV pictures from Apollo 8 at Goldstone. It was no accident therefore, that the Parkes pictures looked the best. In addition, the slow-scan monitors in the scan-converters used high persistence phosphor screens so that the pictures could persist long enough for the Vidicon camera to image them. Unfortunately, a side effect of this was that the images, especially of bright, moving objects (like astronauts), persisted between frames, resulting in the ghosting of the images. Another problem was that the scan-conversion process, introduced additional signal noise and a lower resolution picture.
To make matters worse, relaying the signals via microwave relays, landlines and geostationary satellite added even more signal noise and transmission errors. The result of all these systematic problems was that the TV that the world saw was severely degraded and compromised. We could do much better today. As the video and telemetry downlink was being received at the stations, it was recorded onto 1-inch magnetic data tapes at a rate of 120 inches-per-second. These tapes had to be changed every 15 minutes for the entire duration of the moonwalk. Clearly, if we could find these tapes, we could replay them and recover the original SSTV pictures. With modern image processing techniques, we could enhance them even further and release them to the public.
The tape search begins
Soon after arriving at Parkes in 1996, I learned of a minor controversy about the exact time that the first TV from the Moon was received at Parkes. The Director of the Parkes Observatory at the time, John Bolton, had always insisted that he had received the TV signal from the very beginning when the camera was switched on at 12:54 PM (AEST).
The Moon was not scheduled to come into view at Parkes until 1:02 PM – a full eight minutes later, so there was some doubt. However, I soon learnt that there were two feeds installed in the focus cabin on the day. Realising that the moonwalk was imminent, Bolton was able to receive the signals with the less sensitive off-axis receiver. He carefully aligned the off-axis beam on the Moon and was able to track it until it reached the telescope’s 30-degree elevation horizon at 1:02 PM, after which he could track it normally with the main beam. My calculations showed that this was indeed possible, but I wanted to know for certain. Also, the signal being received by the off-axis feed would have been unstable and probably of a much lower quality, so I wanted to know by how much. I thought that if I could find the original data tapes that contained the signals recorded at Parkes, I could replay them and confirm my conclusions. At this time also, there was still some doubt about the sequence of switches in the broadcast of the TV, so by finding the tapes from the other stations, I could compare their picture quality with the existing video recordings and determine the sequence for certain. A bonus was that we could also recover the original SSTV, which I knew by then was of a much higher quality.
Beginning in the late 1990s I contacted various NASA centres requesting the whereabouts of the data tape recordings. I made countless phone calls, wrote emails and letters to whomever I thought might know where the tapes were located. But, it was all to no avail. No one seemed to know where the tapes were. In fact, many had trouble understanding what exactly I was after. I was convinced that the tapes must still exist somewhere, but where? In 2001 I obtained a Polaroid picture taken directly off a slow-scan monitor at Sydney Video. When compared to the existing scan-converted video image of the same scene, it clearly showed how much better the original SSTV was to the scan-converted videos. So, I persisted.
Also in 2001, the film The Dish premiered in the US and this prompted several past and present NASA personnel to contact me. Three in particular became good friends and search team members. Stan Lebar was the retired Westinghouse engineer who, in 1969, was the program manager for the Apollo Lunar Surface Camera. Dick Nafzger was the Goddard Space Flight Center (GSFC) engineer responsible for all ground systems hardware in support of Apollo TV in 1969, and was still with NASA. Bill Wood was a retired communications engineer who was based at Goldstone in 1969. The search team was completed when, in 2002, I was contacted by Colin Mackellar, who is an amateur historian and the webmaster of the Honeysuckle Creek website. He is a trained geologist and an Anglican minister in Sydney. Together, we joined forces to search for, and recover, the SSTV recordings.
A breakthrough occurred in 2002 when a former technician from Honeysuckle Creek contacted his former colleagues and Colin Mackellar. He admitted that, in 1969, he had made an unauthorised copy of a data tape that he believed contained telemetry from the Apollo 11 lunar EVA. This caused great excitement. The tape had been stored in his garage for 33 years in less than ideal conditions. If it still contained data, the possibility existed that the SSTV could be recovered from it.
Former Honeysuckle Creek personnel, Mike Dinn and John Saxon organised to have the tape transported to the Data Evaluation Lab (DEL) at the GSFC by the NASA representative in Australia, Neal Newman. The DEL contained the only machines in the world that could play and decode the Apollo data tapes. At the DEL, Dick Nafzger replayed the tape with his team. Unfortunately, they discovered that the tape only contained data from a 1967 simulation. The technician had copied the wrong tape. As heartbreaking as this was, it had a positive effect. People suddenly understood what we were after and why we were looking for it. We confirmed that the equipment to replay the data tapes still existed and, most importantly, that even after 34 years the tapes could still retain data.
In 2005, spurred on by this and by new Polaroids from Honeysuckle Creek, Stan and Dick visited the US National Archives in Washington, where all the data tapes from the Apollo era were deposited in the early 1970s – all 250,000 plus tapes. Unfortunately, their search only uncovered a single box of tapes containing Apollo 9 telemetry. The label on the box had details that allowed us to continue the search. Soon after this discovery, we received the alarming news that the DEL was slated for closure in 2006. This would be a disaster because, without the DEL, there would be no way to replay the tapes, and recover the SSTV, if they were ever found. Something had to be done.
The formal search
In February 2006 I visited the DEL and also gave a series of talks at various NASA centres to explain our search. On my return, I compiled a report which slowly began to stir people’s attention. Two months later in July, Stan and Dick were interviewed on national radio on the anniversary of the Apollo 11 mission.
Finally in early August, The Sydney Morning Herald posted a front-page story with the provocative headline ‘One giant blunder for mankind: how NASA lost moon pictures’. This caused a major stir with the story going viral on the internet and news reports appearing on the American TV networks and other news organisations worldwide. Interest became so intense that in August 2006 the NASA Administrator, Michael Griffin, formalised the search and appointed the GSFC deputy director, Dorothy Perkins, to head the search. Dick was the technical lead. The first decision made was to not close the DEL.
With the full resources of NASA brought to bear on our search, we were confident that we would now finally locate the tapes and release the SSTV to the public by Christmas. But it was not to be. Soon after the formal search began, documents were found that suggested that the tapes may have been erased in the early 1980s. This was disturbing news. We were searching for just 45 tapes from over 250,000 tapes of the Apollo era. Surely, these few would have been put aside for historical reasons. Meanwhile, Colin and I followed up leads from the Australian end and provided advice. In the US, our colleagues Stan, Dick and Bill became first-class sleuths. They tracked down long retired personnel and uncovered dusty documents from NASA archives, people’s attics and basements.
Slowly and surely, the evidence mounted. We discovered that in the late 1970s and early 1980s NASA had withdrawn all the Apollo era data tapes from the National Archives and erased and recertified them for later use. But why? Apparently, these tapes were manufactured using whale oil to adhere the oxide to the backing. However, in the mid-1970s, the use of whale oil was banned and manufacturers switched to using synthetic oils. The drawback was that if the synthetic oil-based tapes were not stored correctly, they would absorb moisture from the air which made them sticky. Played back at high speed, they would stick to the recording heads and be shredded to pieces. The older Apollo era tapes didn’t suffer from this drawback.
As NASA’s budget was cut back severely in the late 1970s, the need for more tapes to record the increasing volume of data from satellite programs became acute. The enormous number of tapes in the National Archives was now seen as valuable assets. Over a period of several years, they were all removed, erased and recertified. The labels on the tape canisters were cryptic and there was little way of knowing what each of the tapes contained. Our team didn’t find any evidence that the tapes containing the Apollo 11 lunar EVA data were treated differently to the others. We reluctantly concluded that the tapes were, in all likelihood, erased and reused with the rest.
You can imagine how we felt. To understand why the tapes were treated this way, it’s important to realise that they were never intended to be the primary archival media. In fact, there was never any expectation that the magnetic data would survive more than a few decades. They were only meant to act as backups for the real-time communications relays and other data. If there was a failure during a mission, the tapes could be used to recover the information. If however, all went well, then the tapes were no longer necessary. All the vital information was extracted in real-time and archived for analysis at the relevant NASA centres. The TV was successfully seen by the world and the scan-converted video was properly recorded onto archival b/w film that would last for centuries. Few people outside of the tracking stations were even aware of the SSTV or how much better it was. As far as everyone was concerned, all the data was believed to be properly archived – at least until we came along.
The NASA report HERE
What to do next? In late 2006 Colin noticed a video clip on Eric Jones’ Apollo Lunar Surface Journal website. It showed Armstrong descending the lunar module ladder that was much clearer than anything we’d seen before. We learnt that the clip was sourced from someone who had previously worked at the GSFC. It appears that he found an old 2-inch videotape of the lunar EVA and made a crude VHS video copy of it. We obtained a copy of this videotape and found that it was most likely a copy of the video recording made at Sydney Video of the Australian selection.
It contained the clearest pictures of Armstrong descending the ladder sourced from Honeysuckle. It also showed the switch to Parkes earlier than in any other known recording. Unfortunately, when the original copy was made, the Ampex recorder was not setup properly and this produced a jittery image with many defects. We spent the next few months searching for the original 2-inch tape, but it has mysteriously gone missing. Early in the search Colin was contacted by Ed von Renouard, the former scan-converter operator from Honeysuckle. On the day of the lunar EVA, Ed had brought his home movie camera to work and recorded footage directly off the screens of his console. One of those scenes was the dumping of the astronauts’ portable life support systems, or backpacks. This occurred several hours after the astronauts had re-entered the lunar module and the TV networks had by then ended their broadcasts. Consequently, as far as we could determine, no other footage existed of the dumping. During the search, we came across many archived copies of the scan-converted TV. We decided to switch our search to finding the best of these scan-converted videos and have them archived properly. We also decided to digitise them along with the Sydney Video and Honeysuckle footage. We would take the best parts of each and compile and restore them into a single video of the lunar EVA.
In 2008 we had a demo restoration produced of selected scenes, which we used to convince NASA to underwrite the $245,000 cost of the full restoration. A week later, Neil Armstrong visited Sydney to address the CPA Australia 125th anniversary celebrations. During his address, Neil Armstrong paid a glowing tribute to the many Australians who worked at the tracking stations and helped to ensure the success of the Apollo 11 mission. Some were present in the audience and were individually acknowledged by him. In a brief ceremony following the event, Armstrong symbolically handed over the Australian disks to Dr Phil Diamond, the then-Director of CSIRO Astronomy and Space Science (CASS) – the custodian of the disks in Australia. He noted that ‘”the restored video is a valuable contribution to space exploration and space communication history”.
This ceremony effectively brought the restoration effort to a close. The Australian disks will eventually be deposited in permanent archival storage, most likely with the National Film and Sound Archive in Canberra. The restored Apollo 11 video can now be purchased online from www.apollo11video.com
The proceeds will go toward the continued search and restoration of the other Apollo mission videos.
In early September 2006, soon after we first received news that the tapes may have been erased, I received a phone call from Peter Robertson, the editor of Australian Physics magazine. He had seen the news items regarding the missing Apollo 11 tapes. He phoned to tell me of a letter he had received from John Bolton in the early 1990s. Bolton had mentioned some videotape players that were in the Parkes control room during the Apollo 11 mission. I informed Peter, that we weren’t looking for videotapes but rather magnetic data tapes containing telemetry of the mission. I asked him to send me a copy of the letter anyway.
For many years, I had photographs from the CASS Photo Archive of scenes taken inside the Parkes control room during Apollo 11. Several photos showed a man standing beside Ampex VR660 2-inch videotape players. The Ampex players could only record standard television pictures, so I had no idea what they were doing at Parkes. I also didn’t know who the man standing beside them was, or what he was doing there.
A few days after Peter phoned, the Bolton letter arrived and I was stunned. The letter did indeed describe the Ampex video recorders and, more importantly, Bolton mentioned that they came with their own engineer from Johns Hopkins University in Baltimore. Could this engineer be the mystery man? I knew that Johns Hopkins was the home of the Applied Physics Laboratory (APL), a regular NASA contractor.
In late November 2006, we received definitive evidence that the tapes had been erased. It was then that I sent the information on the possible identity of the engineer to my US colleagues. They immediately set out to find him. Within a few weeks, they found old newsletters from APL that positively identified him. He was contacted and interviewed by Bill and Stan. What he told them lifted our spirits. According to the engineer, in April 1969, the APL was contracted by the GSFC to modify existing Ampex VR660 video recorders to record the non-standard SSTV at Parkes. He was put in charge of this crash program. It was to be an experimental backup recording in case the TV could not be relayed to Houston. This secondary recording was only made at Parkes and if it worked, it could be used on future missions. He reported that the recording succeeded and that he returned to the US with two reels of 2-inch videotape containing the SSTV.
The whereabouts of this videotape was now a mystery. An extensive search was conducted at APL that turned up two tapes that seemed to match the description. Dick organised the loan of an Ampex VR660 video player and a slow-scan monitor from two museums. His team played back the tapes at DEL and found that they were all blank. Again, we were disappointed. Importantly, there was no documentation to suggest the tapes were erased or destroyed. We are working on the assumption that they still exist somewhere, so our search for them continues.
The most striking thing for me was how, just as we were at our lowest ebb, John Bolton appeared, from beyond the grave, to direct us in our search. It was like he was saying, “Hey, look over there. That’s where you’ll find what you’re looking for.” Hope remains.
More information on the Parkes Apollo 11 support and the search for the tapes can be found here:
This is the official NASA search report release in 2009:
This is the page setup in 2009 to publicise the Parkes Apollo 11 40th Anniversary:
This is the site for purchasing the Apollo 11 restored video DVD:
I wish to express my gratitude to Professor Marcus Price, officer-in-charge of the Parkes Observatory in 1997, for asking me to research the Observatory’s support of the Apollo 11 mission, and to Dr John Reynolds, officer-in-charge from 1999–2008, for his continued support throughout. I also thank Marshall Cloyd for giving me the opportunity to search for the tapes a little closer to the source in the United States. Finally, to my friends Bill, Dick, Colin and Stan – thank you.
By Bruce Tabor
On 15 February, the sky over Russia was lit up by a great ball of fire – the Chelyabinsk meteor. NASA’s infrasound data can tell us a lot about it. But amazingly, so can amateur sleuths using YouTube, Google Earth, and some trigonometry.
The Chelyabinsk meteor entered the atmosphere, and exploded at high altitude near the Russian city of Chelyabinsk at 9:20 am local time Friday 15 February. Normally we rely on national space-science agencies to reconstruct these events but with some data from the web and some high school physics, you too could try your hand.
Stefan Geens of Ogle Earth was inspired to use maths to find out about the meteor using footage from car dash-board and building security cameras in Russia, which have proliferated as a way of fighting crime.
He made some assumptions about straight lines and constant speeds, and got some videos of the meteor over Revolution Square, Chelyabinsk. Then he used the distance between light posts to do some trigonometry.
To use this method you need some information. The explosion occurred at an elevation of 40 degrees almost due south of Chelyabinsk’s Revolution Square. The meteor was travelling a little south of due west.
You can get more information about distances using the gap between the flash of light and the sound of the explosion in the security camera footage. Time-stamped surveillance suggests a delay about 2.5 minutes until the shock wave reached the city. Assuming an average speed of sound of say 300 metres per second, you can calculate a distance.
Using two sides and one angle, you’re ready to do some trigonometry. The meteor exploded 45 km away at a height of about 35,000 metres. That’s three times higher than commercial airlines fly.
Most meteors start out their lives as asteroids, but when these rocks enter the atmosphere at high speed they change their name to meteor. Asteroids move through space on their own paths, but if they pass very close to us they can be effected by Earth’s gravity. Some of them enter our atmosphere and become meteors.
It’s friction with the atmosphere that makes them burn up as their kinetic energy gets converted to other forms like heat, light and sound (great balls of fire!).
So how much kinetic energy did the Chelyabinsk meteor have? NASA used infrasound data to find out. They estimate that the meteor had a diameter of 17 metres, a mass of 10 000 tonnes and entered the Earth’s atmosphere at nearly 18 kilometres per second.
Kinetic energy increases with the square of speed, so the astronomical velocity of the meteor meant that it had a lot of energy. And within a fraction of a second this energy of about 2 petajoules – that is 2 with 15 zeros – was converted into heat, light, and a blast wave.
There was 50 times more energy released by the Chelyabinsk meteor than would be released by an explosion of the same mass of TNT. That’s 30 times the Hiroshima blast and the largest energy release from a meteor since 1908 (when the Tunguska event released the equivalent of 10-15 megatons of TNT). Fortunately this blast occurred high in the atmosphere, which is why the damage on the ground was mostly limited to shattered windows.
All I can say is – goodness, gracious, great balls of fire!
This article celebrates 2013, the year of Maths of Planet Earth. The article was written by Bruce Tabor and edited by Arwen Cross. Thanks to John Sarkissian for proofreading for us.
Astronomers using a CSIRO radio telescope have taken the Universe’s temperature, and have found that it has cooled down just the way the Big Bang theory predicts.
Using the CSIRO Australia Telescope Compact Array near Narrabri, NSW, an international team from Sweden, France, Germany and Australia has measured how warm the Universe was when it was half its current age.
“This is the most precise measurement ever made of how the Universe has cooled down during its 13.77 billion year history,” said Dr Robert Braun, Chief Scientist at CSIRO Astronomy and Space Science.
Because light takes time to travel, when we look out into space we see the Universe as it was in the past — as it was when light left the galaxies we are looking at. So to look back half-way into the Universe’s history, we need to look half-way across the Universe.
How can we measure a temperature at such a great distance?
The astronomers studied gas in an unnamed galaxy 7.2 billion light-years away [a redshift of 0.89].
The only thing keeping this gas warm is the cosmic background radiation — the glow left over from the Big Bang.
By chance, there is another powerful galaxy, a quasar (called PKS 1830-211), lying behind the unnamed galaxy.
Radio waves from this quasar come through the gas of the foreground galaxy. As they do so, the gas molecules absorb some of the energy of the radio waves. This leaves a distinctive “fingerprint” on the radio waves.
From this “fingerprint” the astronomers calculated the gas’s temperature. They found it to be 5.08 Kelvin (-268.07 degrees Celsius): extremely cold, but still warmer than today’s Universe, which is at 2.73 Kelvin (-270.42 degrees Celsius).
According to the Big Bang theory, the temperature of the cosmic background radiation drops smoothly as the Universe expands. “That’s just what we see in our measurements. The Universe of a few billion years ago was a few degrees warmer than it is now, exactly as the Big Bang Theory predicts,” said research team leader Dr Sebastien Muller of Onsala Space Observatory at Chalmers University of Technology in Sweden.
“A precise and accurate determination of the cosmic microwave background temperature at z=0.89″, by S. Muller et al. Accepted for publication in the journal Astronomy & Astrophysics; online at http://arxiv.org/abs/1212.5456
MEDIA: Helen Sim Ph: +61 2 9372 4251 E: firstname.lastname@example.org
They’re big, powerful and fast. Top to bottom, they measure about half the Galaxy’s diameter. They contain as much energy as a million exploding stars. And they are roaring along at 1000 kilometres a second (yes, a second).
Revealed by our Parkes radio telescope (aka The Dish): they are giant geysers of charged particles shooting out from the centre of our Galaxy.
The finding is reported in today’s issue of Nature.
“These outflows contain an extraordinary amount of energy — about a million times the energy of an exploding star,” said the research team’s leader, CSIRO’s Dr Ettore Carretti.
But the outflows pose no danger to Earth or the Solar System.
The speed of the outflow is supersonic, about 1000 kilometres a second. “That’s fast, even for astronomers,” Dr Carretti said.
“They are not coming in our direction, but go up and down from the Galactic Plane. We are 30,000 light-years away from the Galactic Centre, in the Plane. They are no danger to us.”
From top to bottom the outflows extend 50,000 light-years [five hundred thousand million million kilometres] out of the Galactic Plane.
That’s equal to half the diameter of our Galaxy (which is 100,000 light-years — a million million million kilometres — across).
Seen from Earth, the outflows stretch about two-thirds across the sky from horizon to horizon.
So how could we have missed them before?
A couple of reasons. The particles are glowing with radio waves, rather than visible light, so seeing the geysers depends on having a telescope tuned to the right frequency (which happens to be 2.3 GHz). And the Galactic Centre is a messy, confusing place where a lot is going on.
VIDEO: Ettore Carretti talks about how the telescope makes maps of the sky.
Our Galaxy has a black hole at its centre, but it’s not that which is powering the geysers. Instead it’s star-power: “winds” from young stars, and massive stars exploding.
About half of all the star-formation that goes on in our Galaxy happens in and near the Galactic Centre. That’s a lot of stars, and a lot of energy.
VIDEO: The Parkes telescope observing as night falls and stars come out and the Milky Way appears overhead. Credit: Alex Cherney / terrastro.com
MEDIA: Helen Sim. Mb: 0419 635 905. E: email@example.com
‘An eclipse adventure in Far North Queensland’, by Robert Hollow
I’ve just experienced a long-held desire to observe one of the most stunning events in astronomy, a total solar eclipse. Yesterday’s eclipse was only visible as a total eclipse in Far North Queensland, with most spectators lining the coast from Cairns to Port Douglas. Not for me the delights of the beach, though, as I was well inland, west of the divide on Maitland Downs cattle station.
What made the event even more special was that I was able to share it with a fantastic, keen bunch of school students from across the region taking part in “Under a Darkened Star” Student Astronomy Conference. Organised by the irrepressible David Platz, teacher and astronomy educator at Atherton State High School and supported by a cast of astronomers, amateur and professional from across Australia, the US and France, the four-day conference took us to the most likely spot along the centre line of the eclipse to have clear skies.
We arrived late Tuesday afternoon and within a short time had an impressive line of canopies erected for the students to sleep under whilst a dedicated team of parent volunteers had the barbecue underway. With dinner out the way, we spent a few hours exploring the dark night skies with a range of telescopes. It was lovely change to be observing without the need to rug up against the cold or battle mosquitoes.
Up before 5am for a final setup a check of our telescopes and cameras, a bright Venus greeted us in the pre-dawn sky. As the sky lightened the anticipation grew. The Sun would already be in the early stages of the eclipse as it rose above the ridgeline opposite our viewing site. At last it was visible! Silhouetting the trees the top left edge of the Sun appeared eclipsed by the Moon.
As the Sun rose the Moon continued its trek across the face. Four sunspot groups added to the spectacle. The students were able to view the eclipse through a variety of telescopes and experimented photographing it with their cameras and smartphones held up to the eyepieces. A video camera connected to a projector allowed us to project a large image on a screen too.
With totality approaching at 6.38am we could feel the temperature drop, the lighting change and the birds stopped singing. Things started happening quickly. The students assembled in a group with instructions to remove their eclipse glasses and view the total eclipse on a whistle blast.
There was a collective gasp on seeing the Sun’s corona and the total eclipse. A truly memorable moment. We had a fraction over two minutes of totality. Never enough, but we made the most of the time. Venus and stars came out and we could see red solar prominences through an unfiltered telescope.
I was able to get a few photos before having to replace the solar filter on my telescope and camera lens. Fortunately, my last photo captured the moment known as the “diamond ring”, a stunning effect.
With another whistle blast the glasses went back on, leaving us another hour to follow the passage of the Moon across the Sun.
By the time it ended it already felt like a much longer day, though in fact we were yet to have breakfast. Fortified with some bacon and eggs and a cup of tea the camp was soon packed up, telescopes disassembled and the students were all back on the buses. It was a sleepy but happy ride back to our base at Lake Tinaroo for the rest of the conference.
I’m no longer an eclipse novice but I think I may have caught the bug.
Robert Hollow would like to thank David Platz, Atherton State High School and the “Under the Darkened Star” Student Astronomy Conference for the opportunity to view the eclipse.
By Helen Sim
Got your ticket to Cairns? Camera gear ready?
No, me neither. But lots of people have, and they’ll all be in Far North Queensland on November 14 (local time), waiting for the Sun and Moon to tango.
The thing is, how can they be so sure this eclipse is going to happen, where and when as advertised? OK, so they have the phone app. But someone has to write the app.
The ancients were app-less. But they spent more time looking at the sky than most of us do now, and some recorded what they saw.
Ancient reports of solar eclipses can be a bit dodgy. However, a credible record on a Babylonian clay tablet mentions one happening on what we’d now call May 3, 1375 BC. Surviving Chinese records of eclipses begin at about 709 BC.
By 273 BC the Babylonians had noticed that the periodicity of eclipses is governed by the “Saros cycle”—a period of 6585.3213 days (18 years, 11 days and 8 hours). This is easiest to observe with lunar eclipses (when the Moon is shadowed by the Earth), but it also applies to solar eclipses.
There’s a nice illustration of Saros cycles here. You’ll notice that although there’s a pattern, it doesn’t repeat exactly. And although the Babylonians knew of the Saros, it’s debated whether they used them to predict solar eclipses.
Successive eclipses aren’t visible from the same part of the Earth (as any eclipse chaser will tell you). Although a total solar eclipse occurs somewhere on Earth about every 18 months on average, at any given place they recur only once every 410 years: 330 years if you’re in the northern hemisphere, and 540 if you’re in the south (again, all those numbers are averages).
The most recent total solar eclipse visible from Australia occurred on December 4, 2002.
The next one, after this 2012 event, will be on July 22, 2028. (It will track across much of Australia, including Sydney.)
There is no simple formula to predict the dates of solar eclipses. In fact, to predict them with a fair degree of certainty, you need a good understanding of the Moon’s orbit and apparent speed of travel (which isn’t constant).
By about 206 AD Chinese astrologers could predict solar eclipses from the motion of the Moon.
The ancient Greeks, building on astronomical knowledge from the Babylonians, could do it too. The amazing Antikythera mechanism, dated to 150-100 BC, was used to calculate positions of the Sun, Moon and planets, and events such as eclipses. It even incorporates the variable speed of the Moon.
Cut to the 17th century. Isaac Newton published his new-fangled equations for gravity in 1687. Now astronomers could (and did) calculate the movements of the Moon better, and thus improve predictions for eclipses.
The calculations weren’t perfect, though. Newton’s colleague Edmond Halley rediscovered Saros cycles (remember those?) and used them to correct calculations made with Newton’s equations. Halley confidently predicted the solar eclipse of May 3, 1715 [April 22 on the old calendar], which was to pass over Britain.
Halley created a map of the eclipse path—he was the first person to do so—and sent it out around the country, asking for people to record the time when total darkness reached them. His own predictions were pretty good: he was out by just four minutes.
By the late 19th century there was a complete mathematical treatment—a mathematical model—of the Moon’s orbit: it required 1500 separate terms and covered several pages of print.
Solar eclipses have been used for science. Most famously, in 1919 British astronomer Arthur Eddington made use of one to test Einstein’s newly published theory of general relativity. In the eclipse coming up, some groups will be using the eclipse to study the Sun’s corona (outer atmosphere), looking for information about how its temperature changes over the 11-year sunspot cycle.
But eclipses are now mostly just a damned good excuse for a party. I’m looking forward to 2028!
J. Marchant, “Mechanical Inspiration”. Nature 468, pp. 496-498 (2010)
D. Steel, “Eclipse: The celestial phenomenon that changed the course of history”. (Joseph Henry Press, 2001)
F.R. Stephenson, “Historical Eclipses”. Sci Am 247 no.10, pp. 154-163 (1982)
By Lisa Harvey-Smith, CSIRO
Today, after several years of design and construction, CSIRO’s Australian Square Kilometre Array Pathfinder (ASKAP) is officially open.
The A$140m facility, built in the remote Murchison Shire of Western Australia, has a dual role as a cutting-edge radio telescope to study the universe and as a technology demonstrator for the planned A$2 billion Square Kilometre Array (SKA).
ASKAP comprises 36 radio dishes, each with a diameter of 12 metres, making the telescope sensitive to faint radiation from the Milky Way and giving it the ability to detect very distant galaxies. It is also a remarkably complex telescope.
A new receiver technology called a phased array feed, developed in Australia by CSIRO, gives ASKAP an unrivalled capability to survey large volumes of the cosmos.
These special cameras increase the area of sky visible to the telescope at any one time by a factor of 30 over existing technology. This increases the scale of the resulting photographs of the radio sky from the size of the full moon to an area larger than the Southern Cross.
The addition of this wide-angle camera boosts the survey speed of ASKAP, allowing astronomers to carry out large “drift-net” surveys, to trawl the sky and gather information on hundreds of millions of galaxies.
By working in this way, the telescope is able to tackle big-ticket research areas such as cosmology and dark energy and gather enough statistical information to study the fascinating life stories of galaxies.
Researchers from around the world are already lining up to use the facility with ten ASKAP science survey teams, totalling more than 700 astronomers, ready and waiting.
These teams are working with CSIRO to design and maximise the scientific value of the surveys, some of which will take around two years to complete. Science verification has begun and some science projects are expected to be underway by the end of 2013.
CSIRO and the science teams are also tackling head-on the challenges involved in extracting – in real-time – scientific knowledge from an extremely large (72 Terabit per second) raw data stream. That’s enough to fill 120 million Blu-ray discs per day.
Dealing with such data volumes is something radio astronomers will have to get used to. In the era of the SKA we will find ourselves interacting less with real telescopes and more often mining online data stores and “virtual observatories”. Not only is the technology changing, the way in which we do our science is also being transformed.
One of the aims of the SKA Pathfinders (the others being the MeerKAT facility in South Africa and the Murchison Widefield Array) is to ensure the next generation of astronomers is ready for this new challenge.
The official opening of ASKAP and the Murchison Radio-astronomy Observatory (MRO) marks the beginning of a new chapter for radio astronomy in Australia. Following the announcement earlier this year of a dual-site arrangement for the SKA, we now know the MRO will host two complementary astronomical instruments during Phase 1 of the project.
One will study low-frequency radio waves emanating from cold gas in the early universe and will build on the scientific and technical expertise gained from the Murchison Widefield Array project. The other will be an array of almost 100 dishes built on the capabilities of ASKAP. This instrument will be used to survey unprecedented volumes of our universe and delve even deeper into it’s secrets.
Over the coming decade the number and capabilities of telescopes available to radio astronomers will grow enormously. Along with the Murchison Widefield Array, ASKAP is leading the way in prototyping cutting-edge SKA technologies at the most radio-quiet observatory on Earth.
It truly is an exciting time to be a radio astronomer!
CSIRO acknowledges the Wajarri Yamatji people as the traditional owners of the land on which the observatory was built.
Lisa Harvey-Smith works for CSIRO and is project scientist for ASKAP.
We’re busily preparing to show off our shiny new telescope, the Australian SKA Pathfinder, to the world. To mark the end of its construction, the telescope will be formally opened next Friday, 5 October. This time-lapse video shows the telescope’s 36 antennas standing tall in the breathtaking Western Australian landscape.
The antennas will begin making detailed pictures of distant galaxies in 2013. ASKAP has been designed to be able to survey the whole sky extremely quickly, providing the opportunity for astronomy projects never done before. Check out the ASKAP webcam or homepage for more information.
Next Friday also marks the official opening of the Murchison Radio-astronomy Observatory (MRO), where ASKAP is located.
CSIRO acknowledges the Wajarri Yamatji people as the traditional owners of the MRO site.