Show notes for June 3rd, 2013
Hosts: Jesse, Lianne, Jen
Title: Cruising with The QEII
It was a busy week for space exploration as three new astronauts joined the ISS crew, ESA launched their ATV4 ‘Albert Einstein,’ and China prepares to launch to their own Space Station. Jen talked about mass concentrations on the Moon, Jesse chatted about our place in the Milky Way, and Lianne told us why going to mars will make you radiant. Show notes and podcast are below. Thanks for listening!
This week in space/astronomy history:
1. June 3, 1948 – the 5 meter (200 inch) reflecting telescope at Mt. Palomar Observatory is dedicated in honour of George Hale. York Universe host Jesse Rogerson performed observations with the telescope in the fall of 2012; see his blog for details.
2. June 3, 1965 – Gemini 4 launched, Ed White takes America’s first space walk. Lianne found a cool photo of this the other day! http://i.imgur.com/DejtU.jpg (‘This is the saddest moment of my life.’)
3. June 8, 1625 – Giovanni Domenico Cassini born. Discovered 4 of Saturn’s moons: Tethys, Dione, Rhea, and Iapetus. Discovered the ‘Cassini Divisions’ in Saturn’s Rings. Also credited with the discovery of the Great Red Spot on Jupiter.
1. Asteroid 1998 QE2 buzzes Earth. The asteroid made its closest approach, 5.86 million kilometers (15 lunar distances), to Earth on Friday, May 31st 2013 at 20:59 Universal Time. At approximately 2.7 kilometers in diameter (or 9 QEII cruise ships!), this asteroid is roughly the same size as the one that produced a mass extinction event 65 million years ago on Earth. As the QE2 got closer to Earth it was found that it had its own moon, sized roughly 600 meters in diameter. NASA said that about 16 percent of asteroids that are 200m or larger are binary or even triple systems. Suggested Reading: Universe Today QE2’s Size, Moon; NASA on QE2’s moon; ASC-CSA’s NEOSSat
2. Proxima Centauri to eclipse background stars. It may seem like stars are fixed in their spots on the sky, however, every star in the Milky Way has some motion, which astronomers call ‘proper motion.’ The change in a star’s position on the sky as a result of proper motion is too small for us to discern over a human lifetime. Astronomers can, however, measure a star’s speed and trajectory in space and therefore predict the future path of a star. The closest star to the Sun, Proxima Centauri, has one of the largest proper motion (this makes sense, the closer something is to us, the faster it will appear to be moving). It is predicted that in 2014 and 2016 Proxima Centauri will move into a position that eclipses, or nearly eclipses, two background stars. As a result, astronomers will be able to measure the mass of the star independently, and even look for exosolar planets. Suggested Reading: Hubble Space Telescope Press Release.
3. Three new astronauts join the ISS. American Karen Nyberg, Russian Fyodor Yurchikhin, and Italian Luca Parmitano joined the crew of Expedition 36 on May 29, 2013. Check out the mission page for more details. Major details: the crew will perform science experiments, most notably from Japan (Aniso Tubule) and ESA’s SOLAR experiment; 5 spacewalks are schedules for the duration of the mission.
ISS related info: ESA is launching up ATV4 supply mission going up on the June 7th, dubbed Albert Einstein. Can Carry a london double bus inside. China is getting set for its next crew launch. The launch window starts this week and goes through June/July.
4. The GRAIL mission found locations of large, dense regions called mass concentrations (mascons) which are characterized by strong gravitational pull. The data confirms that lunar mascons were created when large asteroids or comets impacted the ancient Moon, when its interior was much hotter than it is now. It is believed that the data from GRAIL shows how the Moon’s light crust and dense mantle combined with the shock of a large impact to create the distinctive pattern of density anomalies. These massive invisible regions make the Moon’s gravity uneven, which affects the operations of lunar-orbiting spacecrafts. Suggested Reading: NASA press release
5. Curiosity Corner with Ryan-Marciniak-stand-in, Lianne Manzer. Initial reports of Gale crater being the location of an ancient river bed have been confirmed through more analysis of the data taken during the first 40 days of Curiosity on Mars. Suggested Reading: NASA press release.
Major Topics Discussed:
1. The Local Arm
The Milky Way, the galaxy in which we live, is a spiral type galaxy. Its shape would best be described as pancake-like: it’s flat, it’s round, and has very prominent spiral arms. The 100-billion (or so) stars in our galaxy orbit the centre of the Milky Way much like the planets in our solar system orbit the Sun. As an aside, the other major type of galaxies are Ellipticals, which are shaped more like rugby balls.
When we look out into the universe at other spiral galaxies, like M51, M101, or this beauty for example, it is fairly easy to discern the internal structure. We can see the large central bulge, count the number of spiral arms, and/or determine the presence of a bar. It is much harder to find and analyze the internal structure of the Milky Way, because we are looking at it from within. Nevertheless, great progress has been made in the understanding of the structure of the Milky Way.
Our Sun is located in what’s known as the ‘Local Arm,’ or ‘Orion Arm.’ This spiral arm is located between two very large arms: the Sagittarius Arm (closer to centre of MW) and the Perseus Arm (closer to the edge of the MW). Originally, the Local Arm was thought to be a small spur between the two other mighty arms of the Milky Way, but recent research is showing that our Local Arm is a lot bigger than we thought.
To determine this, researchers from a variety of institutions including Harvard-Smithsonian Centre for Astrophysics and the Max-Plank Institute for Radio Astronomy, set out to use the National Radio Astronomy Observatory to measure the distances to stars. The astronomers used data from the BeSSel Survey (Bar and Spiral Structure Legacy Survey), which is a survey to study the internal structure and kinematics of the Milky Way by measuring the parallax distances and proper motions to star forming regions. The 10 radio dishes being used are specifically looking for methanol and water maser emission that are associated with young massive stars and compact HII regions that are known to trace spiral structure.
The resulting measurements showed our Orion Arm is much bigger than once thought. They determined the length to be approximately 5 kiloparsecs, and its angle to be more similar to that of the other two major arms.
The PrePrint Paper: http://arxiv.org/abs/1304.0526
UniverseToday.com: Our Place in the Galactic Neighborhood Just got an Upgrade
The BeSSel Survey: https://science.nrao.edu/science/key-science-projects/ksp_bessel
2. Radiation measured by Curiosity on voyage to Mars has implications for future human missions
Curiosity’s Radiation Assessment Detector (RAD)
560-million- kilometer journey
NASA wants to send astronauts to Mars in the 2030’s,
Two types of radiation pose potential health risks to astronauts in deep space:1. Galactic cosmic rays (GCRs): particles caused by supernova explosions and other high-energy events outside the solar system 2. Solar energetic particles (SEPs): associated with solar flares and coronal mass ejections from the Sun.
Radiation exposure is measured in units of Sievert (Sv). Studies have shown exposure to radiation increases a person’s lifetime cancer risk . Exposure to a dose of 1 Sv, accumulated over time, is associated with a 5 percent increase in risk for developing fatal cancer.
Time to get to Mars: Curiosity was 253 days (8.4 months)
Radiation per day: 1.8 milliSieverts (Only about 5 % was from SEPs due to the shielding of the spacecraft.)
Total Radiation: 253 * 1.8 milliSieverts/day = 455.4 milliSieverts = 0.4554 Sieverts (
4.5 times the typical 6 month exposure of astronauts aboard the ISS (100mSv) but LEO is shielded by magnetic field)
Total Increased Risk of Cancer : 2.5%
NASA allowances: 3% career limit
“In terms of accumulated dose, it’s like getting a whole-body CT scan once every five or six days,” said Cary Zeitlin from the Southwest Research Institute (SwRI) in San Antonio, Texas.
GCRs tend to be highly energetic, highly penetrating particles that are not stopped by the modest shielding provided by a typical spacecraft. Extra shielding is needed!
Can be solved by: increased shielding and more powerful propulsion.
The surface data will be published in the next few months.
This graph compares the radiation dose equivalent for several types of experiences, including a calculation for a trip from Earth to Mars based on measurements made by the Radiation Assessment Detector (RAD) instrument shielded inside NASA’s Mars Science Laboratory spacecraft during the flight from Earth to Mars in 2011 and 2012. The data show that during a typical 6 month cruise to Mars the astronaut crews would be exposed to more than 3 times the typical 6 month exposure of astronauts aboard the ISS. The scale is logarithmic; each labeled value is 10 times greater than the next lowest one. The “dose equivalent” units are millisieverts. Credit: NASA/JPL-Caltech/SwRI
Astronomy.com – Radiation Measurements from Curiosity
UniverseToday.com – Human Voyages to Mars Pose High Cancer Risk
Where In The Universe:
Last Week’s Image: http://yorkuniverse.com/wp-content/uploads/2013/05/WITU_ep154.jpg
Correct Answer: Veil Nebula
Correct Guess: Mike Boers on Facebook and Twitter and Randy Drayton on Facebook
This Week’s Image: http://yorkuniverse.com/wp-content/uploads/2013/06/WITU_ep155.jpg
You can answer via email, fb, twitter, or shouting really loudly (though we may not hear that).
Thanks for listening!
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