Thursday 27 October 2016

Sports-Themed Gothic Literature, Two Stories, Free for Halloween



Two Stories, Free for Halloween

For the Halloween weekend, we have two NEW unsettling stories (as Halloween stories should be), both with a sporting theme.  October 28 to November 1, 2016.

Take Me Out to the Ballpark

Murder and Baseball are as American as Apple Pie.  This story is quite a departure for writer Helena Puumala, who usually tells much sunnier tales.


  

A Dark Horse

Horse-racing is known as the Sport of Kings, or is it the Sport of Devils?  A gambler can’t quite be sure, in this mash-up of Damon Runyon and Christopher Marlowe story-telling styles.  Has he sold his soul for a winning streak or not?






Tuesday 18 October 2016

The ESA Rosetta Mission to a Comet – A Talk at University of Alberta by Matt Taylor (Part 2)



The ESA Rosetta Mission to a Comet – A Talk at University of Alberta by Matt Taylor (Part 2)
On Tuesday Oct 4, 2016, Dr. Matt Taylor, the Project Scientist of ESA’s Rosetta Comet probe did a talk at the University of Alberta.  This, of course, is the fascinating mission to comet 67-P/Churyumov-Gerasimenko, which was launched in 2004 and rendezvoused with 67-P in 2014.  It has just recently (late Sept 2016) been decommissioned, via flying it into the comet. For simplicity, I will generally refer to it as 67-P or “the comet”, much as Matt Taylor did during the lecture.

The talk was enormously well attended and well received.  Here are some of my notes from the presentation, in point form.
I have broken the blog into two parts, since there is a lot of information.  Part 1, published last week described  an overview of the mission and the trip to the comet.  Part 2 focuses on the mission once the craft had caught up with the comet.

 

The Speaker

·         Dr. Matt Taylor has a PhD in space physics from the Imperial College of London.  His undergrad was in physics, from the University of Liverpool.
·         He has been with the ESA (European Space Agency) since 2005, working on the Cluster project and the ESA-China Double Star mission.
·         The Cluster mission is based on a set of 4 satellites flying in formation around the Earth, measuring the solar wind and its effect on the Earth.
·         He became involved with the Rosetta mission in 2013 and has been with it since then.  As he noted on several occasions, he was just one part of a large team of professionals of all sorts, that were jointly responsible for the success of the mission.
·         As he noted, the Rosetta mission has been quite different from the Cluster mission.  For one thing, it is easier to explain to his mother (and most of the public) – after all, flying a spacecraft around a comet, then landing a probe on it, is more intuitive for the average person than mapping the solar wind and its interactions with the Earth.
·         He is an excellent speaker, and livened up the talk with some comments about: 
o   The various conspiracy theories generated by the mission.
o   Rock band Queen’s member Brian May’s (who is also an astrophysics PhD) following of the mission.
o   The metal band Napalm Death has also given shout-outs to the Rosetta mission.
o   He also made many amusing allusions to SF pop culture’s intersection with Rosetta, particularly the Star Wars saga (but others, such as Star Trek, Battlestar Gallactica and Blade Runner got some mentions too) .



Part 2

The Journey with the Comet


From ESA website and Matt Taylor’s talk

  • Rosetta’s target was first discovered in 1969.  It has visited the inner solar system several times since then (every 6.5 years).
  • The idea of the mission was to rendezvous in the colder regions of the solar system so that mapping could go forward, and the lander could look at the surface up close.
  • As the spacecraft caught up with the comet (Jan to May 2014), more details about its shape and surface were revealed.  It became clear that the comet is very un-smooth, for example.
  •  


·        

  • The detailed structure of the comet was then mapped and named (summer of 2014), with features names being drawn primarily from Egyptian mythology).
  • It is now mostly a left-over nucleus, though there was still substantial off-gassing of the comet during the mission, especially during the latter stages.
  • After catching up with the comet (August 2014), mission scientists and planners only had a few months to determine where to put down the lander Philae.
  • ·        



  • As noted above, Philae had several docking mechanisms, to enable it to stick to the comet.
  • Touchdown was successful (November 2014), but the harpoons didn’t work, and thus the lander “bounced” to a different location on the surface.
  • The touchdown speed was about 1 km per second, a walking pace.  However, due to the low surface gravity, the “bounce” was over a kilometer.
  • Matt Taylor thought that this might have been a bit of luck, as it ended up in a more interesting spot than its target locations was, so much was learned, even though the time was shorter.
  • The lander took measurements for about 60 hours, then went to sleep.  Contact with the lander was lost in July 2015.
  • The orbiter made several close approaches to the comet after that, through 2015 and into 2016.  However, it couldn’t stay very close for very long, as the dust coming off of the comet interfered with the star-tracker mechanism that lets the spacecraft know where it is in space.
  • The dust is also highly electrically charged.  The spacecraft had the same (negative) charge, as a result of its interaction with the space environment (plasma, solar particles), so this effectively slowed the dust down when it collided with Rosetta.  Thus, the collisions were low speed and not very dangerous (averaging about 1 to 3 km per second).

·        


  • There was both compact dust and “fluffy” dust. The fluffy dust is thought to be primordial, similar to interstellar dust, that was accreted by the comet in deep space.
  • In addition, boulders as large as one meter across were observed being emitted by the comet.  Matt Taylor informed us that conspiracy theorists had fun with that, comparing it to a Battlestar Gallactica Ceylon fighter.
  • The lander seemed to go into shadow, so further contact was lost.  It couldn’t recharge its batteries, as the solar cells were not getting sunlight.
  • Signals from the lander were regained for a short time in June, though they were lost again.  We don’t know why contact wasn’t re-established after that short contact though, as the orbiter was in a position to receive another signal.
  • In August 2016, the lander was located.  We got a very nice shot of the lander then.
  •  

  •  
  • The orbiter was “landed” (or crashed, if you like) on the duck’s head on September 29, 2016.  It went down into a pit in the region known as “Ma’at”, which is an Egyptian reference, but also suspiciously like the name of the project scientist.  Here’s an image from about 1.2 km.

·         



  • ·         The last image received was from about 20 meters above the surface.

·        


  • The decision to crash the craft into the orbit was based on several lines of reasoning:
  •      o   Power was running out, and the situation wouldn’t improve, due to the orbit of the comet moving away from the sun.
  •      o   The spacecraft was old now, and had some mechanical issues.  It seemed unlikely that it would last through another hibernation period.
  •      o   It was getting difficult to control the craft’s orientation in space, so contact with Earth might well have been lost, even if the craft was still operative.
  •      o   Costs were no doubt a factor, though Matt Taylor didn’t explicitly mention this, as far as I can recall.



The Science of the Comet

·         Some highlights of the analysis of the data:

o   It became clear that the comet has “seasons”, as different aspects of it are sunlit or in shadow, due to the comets rotation access remaining fairly constant.

o   The north (the duck’s head) tends to be more dusty.

o   The surface is quite fractured, probably due to thermal stresses as the comet rotates.  This causes heating and cooling cycles, whereby the temperature can vary in a range of about 100 degrees Celsius, over 3 to 4 hours. 



o   There are also smooth areas, which can include “sand dunes”, though there is no wind to generate them, as there is on Earth.  That seems to be due to sublimation of gasses.



o   There a pits and voids, somewhat like Karst topography on Earth, though obviously not caused by the same processes.

o   Surface ice is visible.  When it melts, it can cause the collapse of cliffs.

o   The off-gassing includes a lot of gases that wouldn’t be pleasant to smell.  That helps to tell what the comet was originally made of though.

o   A very significant finding was that of molecular oxygen, along with molecular nitrogen and noble gases.  Molecular oxygen was unexpected.

o   These findings lend support to the idea that the comet was born in a very cold region of the protoplanetary nebula.  It also appears to have formed quite slowly.

o   The deuterium level in the hydrogen indicates that the comet’s water is not chemically the same as Earth’s water.  So, the Earth’s water doesn’t seem to have come from comets.

o   About one million tons of water per day are lost.

o   At perihelion, it appears that about one percent of the comet’s mass is lost.

o   So, the comet will get smaller and smaller over time.  There will probably be very little left of it within 5000 years or so.

o   It is thought that the comet was not that big (maybe 10 km or so in diameter) when it formed.  However it spent most of its existence in the outer solar system, before some passing object perturbed it gravitationally, and it got kicked into the inner solar system.

o  Recent orbital modelling work by researchers at Western University (in Canada) suggests that the comet probably migrated into the inner solar system about ten thousand years ago, probably from the Kuiper Belt, beyond Neptune.

o   At least one amino acid was discovered, along with some other organic chemistry compounds.

o   What causes the duck shape?  It is probably because of two objects colliding at low speed and being jammed together.

o   The two halves of the comet seem different.  There may be a density difference, but there is recirculation of dust between the north and south, which makes it difficult to be sure about these differences.

o   The nucleus is very porous.  It may be as much as 80% void space.

o   The pits have considerable structure, as does the comet overall.  Some features seem to replicate at various scales (i.e. the structures look similar at long distances as they do when you get closer).

o   The boundary where the magnetic field of the sun is screened by the outflowing gas of the comet was substantially larger than was expected, and existed farther from the sun than was expected.

And here is where Rosetta was at the end of Sept 2016 (on the comet's surface). By year's end it will be closer to Jupiter, as both the comet and the planet are heading in the same general direction:


Sources


·         Notes from Matt Taylor’s talk at the University of Alberta, Oct 4, 2016.

 =================================================================

Science Fiction to Read

Now that you have read some real science (astronomy and astrophysics), you should read some science fiction.

Kati of Terra

How about trying Kati of Terra, the 3-novel story of a feisty young Earth woman, making her way in that big, bad, beautiful universe out there.


The Witches’ Stones

Or, you might prefer, the trilogy of the Witches’ Stones (they’re psychic aliens, not actual witches), which follows the interactions of a future Earth confederation, an opposing galactic power, and the Witches of Kordea.  It features Sarah Mackenzie, another feisty young Earth woman (they’re the most interesting type – the novelist who wrote the books is pretty feisty, too).





Wednesday 12 October 2016

The ESA Rosetta Mission to a Comet - Part 1



The ESA Rosetta Mission to a Comet – A Talk at University of Alberta by Matt Taylor (Part 1)
On Tuesday Oct 4, 2016, Dr. Matt Taylor, the Project Scientist of ESA’s Rosetta Comet probe did a talk at the University of Alberta.  This, of course, is the fascinating mission to comet 67-P/Churyumov-Gerasimenko, which was launched in 2004 and rendezvoused with 67-P in 2014.  It has just recently (late Sept 2016) been decommissioned, via flying it into the comet. For simplicity, I will generally refer to it as 67-P or “the comet”, much as Matt Taylor did during the lecture.

The talk was enormously well attended and well received.  Here are some of my notes from the presentation, in point form.
I have broken the blog into two parts, since there is a lot of information.  This is Part 1, which describes  an overview of the mission and the trip to the comet.  Part 2 will focus on the mission once the craft had caught up with the comet, and will be published next week.

The Speaker


  • Dr. Matt Taylor has a PhD in space physics from the Imperial College of London.  His undergrad was in physics, from the University of Liverpool.
  • He has been with the ESA (European Space Agency) since 2005, working on the Cluster project and the ESA-China Double Star mission.
  • The Cluster mission is based on a set of 4 satellites flying in formation around the Earth, measuring the solar wind and its effect on the Earth.
  • He became involved with the Rosetta mission in 2013 and has been with it since then.  As he noted on several occasions, he was just one part of a large team of professionals of all sorts, that were jointly responsible for the success of the mission.
  • As he noted, the Rosetta mission has been quite different from the Cluster mission.  For one thing, it is easier to explain to his mother (and most of the public) – after all, flying a spacecraft around a comet, then landing a probe on it, is more intuitive for the average person than mapping the solar wind and its interactions with the Earth.
  • He is an excellent speaker, and livened up the talk with some comments about:
  •        o The various conspiracy theories generated by the mission.
  •    o   Rock band Queen’s member Brian May’s (who is also an astrophysics PhD) following of the mission.
  •    o   The metal band Napalm Death has also given shout-outs to the Rosetta mission.
  •    o   He also made many amusing allusions to SF pop culture’s intersection with Rosetta, particularly the Star Wars saga (but others, such as Star Trek, Battlestar Gallactica and Blade Runner got some mentions too) .



An Overview of the Rosetta Mission’s Purpose


  • The purpose, of course, was to visit a comet and gain close-in scientific data on its composition and other features of interest.
  • Comets are assumed to contain relatively pristine material, from around the time that the solar nebula first formed the sun and planets.  So, examining a comet gives us information about how the solar system, our home, came about.
  • Comets are thought to be short term visitors to the inner solar system, for the most part.  They have spent most of their existence in the far, outer solar system, before their orbits are perturbed enough to send them into our part of the solar system.  Thus, their material should be mostly unchanged, since the solar system’s formation, billions of years ago.
  • There have been theories that most of the water in the Earth’s oceans came from comets and asteroids during the early stages of the solar system.  So, one of Rosetta’s purposes was to get some close-in data, to support or refute that.
  •  Likewise with the elements needed for life – the so-called “organic” elements, primarily carbon (as Earth life is carbon-based).  Were these brought to the Earth by asteroids and comets, in the early days of the solar system?
  • Of course, comets have just flat-out fascinated humanity for as long as we have records.  Some cave art might depict comets .
  • Certainly there are many famous depictions of comets in historical art, such as the Bayeux Tapestry, which depicts Halley’s comet.






  • Thus, a comet mission is a natural.  In fact, the precursor of Rosetta was to be a sample return mission, though that never happened.  Instead, the lab (the Philae lander) was brought to the comet.
  • Note that there have been flyby missions to comets in the past (the NASA Deep Impact mission for example), but Rosetta was the first tourist to visit, orbit and ultimately settle down, so to speak.
  • The comet chosen for the Rosetta mission is known as 67-P/Churyumov-Gerasimenko.   For simplicity, I will generally refer to it as 67-P or “the comet”, much as Matt Taylor did during the lecture.
  • Note that the designation 67-P stands for the 67th periodic comet discovered.  Halley’s comet was the first, so it is officially called 1P/Halley.
  • Before the mission, 67-P was thought to be a 4 km potato shaped object (from the best Earth-based photos).  Now, we know that is actually 4100 meters long and shaped like a rubber duck.  That’s progress.
  • This photo reminds me more of the head of a Tyrannosaur, though.  Jurassic Park, Jupiter Division. 


·       
 
·          


 

The Spacecraft

  
from Matt Taylor’s comments and the ESA website

  • The Rosetta orbiter was about 32 meters long, about the size of a bus.  Most of that is the array of solar panels, though.  The main structure of the spacecraft was about 3 meters by 2 meters by 2 meters.
  • The total mass was about 3000 kg, and about half of that was propellant.
  • The solar panels put out about 850 watts at 3.4 AU, about 400 watts at 5.25 AU.
  • For comparison, at the Earth’s surface, 4 “largish” standard residential solar panels would probably put out about 850 watts, on a nice summer’s day, at around noon (well, mine do about 250 watts per panel at that time, anyway).  Of course, Rosetta’s solar panels were only very rarely in shadow, so they operated 24/7.
  • The orbiter had 11 scientific instruments, among them, cameras, mass spectrometers, dust analysers, radar, and other imaging instruments.
  • The Philae lander weighed about 100 km, and was about the size of a washing machine (North American variety).  It had various devices, that were intended to make it “stick” to the comet upon landing, such as harpoons that could be fired into the surface.  As we now know, they didn’t work well enough, so the lander bounced about a km.

·        


  • The lander also carried a spectrometer, cameras, radio-wave probes, gas analysers, a magnetometer, even a drill and an oven to examine samples.
  • The name Rosetta refers to the “Rosetta Stone”, the ancient Egyptian artifact that was instrumental in translating ancient Egyptian hieroglyphics, so that modern people could understand their language.  This was meant to reflect the hope that the findings of the Rosetta space mission could help us understand the composition and formation of the early solar system.


The Trip to 67-P/Churyumov-Gerasimenko

From ESA website and Matt Taylor’s talk

  • In March 2004, the spacecraft was launched with an Ariane 5 rocket.
  • Even this powerful rocket couldn’t launch the probe directly to the comet – that  just takes too much energy.
  •  

·        


  • So, the spacecraft took advantage of several “slingshot” manoeuvres, whereby the rocket picks up momentum (and thus velocity) from the inner planets (Earth and Mars, which are “inner” relative to the comet’s location), as it passes by them.
  • There’s a really nice animation of the trip on the ESA site.  Here’s a screen capture and a link (at the end of the blog). 

 

  • There were 4 flyby “kicks”, three from Earth (2005, 2007 and 2009) and one from Mars (2007).
  • It got some nice photos during those approaches.  Matt Taylor showed an especially dramatic shot of Mars, taken during that flyby.  The spacecraft itself is in the foreground, of course.
  •  
  •  

·        
·          


  • Here’s a nice Feb 24, 2007 shot of Mars, taken as Rosetta approached the planet, from the Planetary Society’s website.

·          
·        

  • There was a short communications blackout after passing Mars, when Earth was eclipsed.  Then it did a couple more Earth flybys to pick up more speed, before heading for the comet, out around Jupiter.
  •  Here’s a shot of Jupiter, taken by Rosetta when it was near Mars.  The photo is nothing special, it’s just the idea of taking a picture of Jupiter from a spacecraft near Mars that’s is pretty cool, when you think about it.

·        


  • On the way, though, it observed some asteroids, from fairly close distances (a few thousand km).
  • Then it went into hibernation for a few years (May 2011 to Jan 2014), switching off most systems.  That helps to minimize power and fuel consumption (and costs) while the craft is in a fairly uninteresting region of space.
  • It came out of hibernation in Jan 2014 and arrived at the comet in August 2014 (after some braking manoeuvres, to match the comet’s speed).

End of Part 1 (Part 2 to come next blog)


Sources

·         Notes from Matt Taylor’s talk at the University of Alberta, Oct 4, 2016.


 ----------------------------------------------------------------------------------------------------

Science Fiction for you to Read

Now that you have read some real science (astronomy and astrophysics), you should read some science fiction.

Kati of Terra

How about trying Kati of Terra, the 3-novel story of a feisty young Earth woman, making her way in that big, bad, beautiful universe out there.


The Witches’ Stones

Or, you might prefer, the trilogy of the Witches’ Stones (they’re psychic aliens, not actual witches), which follows the interactions of a future Earth confederation, an opposing galactic power, and the Witches of Kordea.  It features Sarah Mackenzie, another feisty young Earth woman (they’re the most interesting type – the novelist who wrote the books is pretty feisty, too).