Category Archives: Physics

Know Your Rights – Satellites Crashing Onto Your Property

Posted on by

After a bit of stochastic web-enabled research (( i.e. random searching looking for the conclusion of this case triggered by catching up on a story of Rich’s. )) I found this little piece of information from the UNSW Law Journal that everyone should bookmark away just in case they need it..

There’s A Satellite In My Backyard! – Mir And The Convention On International Liability For Damage Caused By Space Objects.

But what is the legal position in relation to damage caused by the return to Earth of a space object such as Mir? Are there any rules in place to cover such an eventuality? Under what circumstances would Russia have been responsible at international law for any such damage? What would be the extent of its liability? How is damage to be measured and what procedures (if any) are in place to facilitate compensation claims and to arrive at a determination of responsibility and its consequences? Once a determination is made, is it a legally binding and enforceable decision?

Just remember where you read it when you need it.. 😎

China Destroys Satellite in Weapons Test ? (Updated)

Posted on by

An interesting news article from the BBC, it is believed that the Chinese military did an anti-satellite weapons test against an old weather satellite of theirs and successfully destroyed it with a surface launched ballistic missile.

The report said that a Chinese Feng Yun 1C polar orbit weather satellite, launched in 1999, was destroyed by an anti-satellite system launched from or near China’s Xichang Space Centre on 11 January.

There is the usual outrage over the test, but I do wonder whether they would have said anything if it was the US who had done the same..

Update: China has confirmed that this test took place.

Quenamari Ice Plateau

Posted on by

Dear Lazyweb,

Reading New Scientist for 2nd December 2006 I came across an article about the Quenamari ice plateau in their “This Week 50 Years Ago” section:

The strange feature of this ice formation is that it exists apparently without fresh supplies of moisture in the middle of a region which is entirely free from ice and snow for most of the year despite its altitude of about 18,000 feet above sea level. No glacier feeds this ice; no high mountain peaks are near enough to snatch rain from the clouds to water it. It is unique – so glaciologists say – and its existence remains a mystery.

Problem is that when you search for what’s known about it now there’s very little information, either how it formed or even whether it still exists given the current episode of global warming that’s going on.

Anyone got any clues ?

How Big Was North Korea’s Bomb ?

Posted on by

My good friend Alec wrote on hearing about the DPRK nuclear test:

One presumes that there is a small chance it’ll have been staged with conventionals;

That got me thinking – how large a bomb was it ? We know the USGS detected a mag 4.2 shock so I went hunting around to see if there was an algorithm for converting magnitudes on the Richter Scale into energy, and, hopefully, into kilotons or megatons. It turns out J.C. Lahr wrote up a method for the “Comparison of earthquake energy to nuclear explosion energy” and helpfully included a piece of Fortran code to create a table of comparisons.

A quick “apt-get install gfortran” and a bit of mucking around with the code and I had an approximate answer:

Mag.   Energy      Energy      TNT         TNT         TNT         Hiroshima
       Joules      ft-lbs      tons        megatons   equiv. tons  bombs
4.2   0.126E+12   0.929E+11   0.301E+02   0.301E-04   0.201E+04   0.134E+00

So a magnitude 4.2 earthquake is (roughly) equivalent to a 2 kiloton device, less than one fifth of the size of Hiroshima bomb. This means it’s probably unlikely to have been a conventional device.

So what North Korea tested was fairly small in these days of megaton devices but certainly nothing you’d want to be anywhere near..

Mars Reconnaissance Orbiter HiRISE Camera Returns First Low-Level Image

Posted on by

Yay! After months of waiting NASA’s MRO has reached its science orbit and taken its first snap with its HiRISE camera. NASA has a press release with a link to the gallery page of the image which has a scale of about 1 foot per pixel. They also have an 8MB TIFF “sub-image” available for download from the MRO’s calibration gallery.

But for the very latest you’ve got to check out the HiRISE team blog where they already have the fact that the second image is down, of layered deposits at the Martian North Pole.

Below is the first image!

First MRO HiRISE Image (NASA)

Update: the page with the full image from which the above sub-image was taken is also available, but be warned, the full size JPEG is 23444 x 23377 pixels and ways in at a hefty 111.8 MBytes!

Research Challenges in Astronomy

Posted on by

I’ve been at the first APAC All Hands Meeting this week, generally hearing what all the other people in the APAC Grid project are up to and meeting folks from around the country that I only otherwise get to see via Access Grid.

Today was the turn of some of the science areas to tell us what they are up to and what they see their big challenges being, and the most scariest (from an HPC perspective) was the session on Astronomy and Astrophysics by Peter Quinn (formerly of the ESO and now a Premier’s Fellow at UWA).

The most intimidating points I picked up from his presentation were:

  • Data explosion – doubling time T2 was < 12 months, with new big survey projects such as VST and VISTA that will become T2 < 6 months!
  • Disk technology T2 is 10 years at present (according to Peter), and slowing.
  • The Large Synoptic Survey Telescope is reckoned to capable of producing 7 PetaBytes per annum of data.
  • The ESO’s data archive is currently (2006) 100TB in 10 racks and using 70kW of power. By 2012 it is forecast to be 10PB in 100 racks and consuming 1MW of electricity.
  • A recent Epoch of Reionisation simulation of 5,0003 particles on a 1,000 CPU Opteron cluster used 2 months of CPU time and 10TB physical RAM (about 10GB per core) and produced about 100TB of output data.
  • Catalogue sizes are exploding, in 2000 there were about 100,000 galaxies in a catalogue, by 2010 that will be 1 billion.
  • Algorithms are not scaling with these data sizes – an algorithm that took 1 second in 2000 will take 3 years in 2010!

But these problems pale into insignificance when you consider the massive Square Kilometre Array (SKA) radio telescope, it is forecast to produce 100 ExaBytes (that’s one hundred million TeraBytes) of data annually!

This raises a number of very fundamental issues:

  • The terabit speed network technologies needed to get the data off the detectors does not exist (yet).
  • There is no storage technology to cope with the volumes of data.
  • This means they will need to process the data on the fly in a highly parallel manner.
  • This is a radio telescope, so there is no time when it cannot take data, unlike an optical ‘scope. This means you cannot somehow buffer the night time data and then process it during the day.
  • If the ESO estimate of 1 megawatt of power for 7 PB is correct, and assuming that power per PB stays roughly and they do store all 100 EB of data, then the storage of one years data will need about 14GW of generating capacity.

Fortunately construction of the SKA isn’t due to start until 2013, so we’ve got a bit of time to solve all these.. 🙂