Title: Why Space Telescopes Need a Union
Written By: Aaron
(DRAFT script - not final)


     Pamela: Welcome to another edition of Slacker Astronomy. Each week we bring you another news event from the world of astronomy. And when there is nothing to report, we'll work on getting a restraining order for the protestors outside.
     Chant: Hey hey, ho, ho, slacker astronomy must go! hey hey, ho, ho, who needs this stupid show?!
     Travis: You know, they are really starting to get on my nerves.
     Pamela: Patience, my friend. They just want attention, ignore them and they will go away. 
     Travis: I'll try. 
     Pamela: This week's story has two neat angles. Not only is the discovery itself fascinating, but how they managed to figure it out is cool in its own right.
     Pamela: We begin with an ex-space telescope. The Infrared Space Observatory, or ISO for short, was an orbiting infrared telescope operated by the European Space Agency from 1995 to 1998. Since it detected light in the infrared, it studied phenomenon in the universe that is cooler than what we can see with the Hubble Space Telescope.
     Travis: It took almost 20 years and around a hundred million dollars to build and operate. It lasted about 2 and a half years in space before it was switched off and deorbited on May 16, 1998.
     Pamela: To observe the Universe in the far infrared requires a detector that is cooled to nearly absolute zero. In this case, Helium was used as a coolant on ISO's primary detector instrument, called ISOPHOT. So it's lifespan of 2.5 years was determined by how long the on board Helium stores lasted.  As a result, observing time on this telescope was precious.
     Travis: A telescope in space turns by spinning various gyroscopes using electricity. These gyros create angular momentum which causes the telescope to swivel. When many are used together, very precise pointing is possible. 
     Pamela: ISO slewed around the sky at a rate of around 8 degrees per minute. That's pretty slow compared to something like a backyard amateur telescope. It took about a minute for the telescope's field of view to move across the sky a length equivalent to your fist fully extended from your body.
     Travis: Since time was so valuable, clever engineers and astronomers devised a way to make this slew time work for them. Instead of shutting off the telescope while it moved, they turned on the detectors and took snapshots. Since it moved relatively slowly, they could take relatively long exposures until the stars began to blur and trail. 
     Pamela: So ISO was always working, all the time. It was freezing cold and had no rest.
     Travis: The Union of Concerned Space Telescopes considered filing a grievance. This was Europe, after all. 
     Pamela: So not only did ISO have thousands of unique targetted observations in space, it also covered much of the sky while slewing to those observations. Scientists published the combined data and called it the ISOPHOT Serendipity Survey. 
     Travis: In total it covered about 15% of the sky. A map of its coverage is in the album art of this podcast and in the show notes at slackerastronomy.org. ISO conducted over 10,000 of these slews during its short tenure in space. Among these so-called free images are observations of about 3,000 galaxies.
     Pamela: They also found 50 places where they think big stars are being born. These high-mass stars are much more massive than our Sun. Like high mass stars on Earth - such as john belushi and chris farley - they live short and intense lifecycles. These stars live and die over the course of a few hundred million years - versus many billion years for our own Sun - they burn fiercely and most eventually explode as supernovae.
     Travis: Because of their short lifespans there aren't many of these stars in the sky to look at. And most of the ones we know of are near the galactic center where they are hidden behind dust lanes.This is where ISO comes in.
     Pamela: By looking in far infrared light, ISO can see beyond much of the obscuring dust. In the show notes on our site is a picture of one of the fields ISO looked at. In optical light, it looks like a black dust cloud in front of a background of stars. But in the infrared, it glows with the activity of young, massive stars.
     Travis: The light these massive stars emit is very energetic and mostly in the ultraviolet band. So why do we see them when looking in the cool infrared band?
     Pamela: Some of the light is absorbed by the intervening dust cloud. The dust heats up just a bit and then reemits the light as thermal radiation - just like glowing coals after the fire is out. This thermal radiation is very cool and requires infrared telescopes to see.
     Travis: For more about young, massive stars check out our interview with Dr. Sally Oey on the SA Extra feed. She is a specialist on these stars and describes them better than we can.
     Pamela: My dog can describe it better than we can. 
     Travis: You mean he has time to read about astrophysics in between peeing on strangers shoes?
     Pamela: You'll never forget that will you?
     Travis: The question is, did your date?
     Pamela: Let's just say that she has had many opportunities to make it up to my date.
     Travis: Using the ISO data, astronomers at the Max Planck Institute in Germany were able to measure the size of one of the young massive star forming regions. In this region, they measured enough mass to make up a star 75 times as big as our Sun. 75 times! That's almost 11 in dog years.
     Pamela: Mental note, we need a dog year to light year calculator for the web site.
     Travis: If an intrepid listeners wants to make one, we'll link to it.
     Pamela: Way to pass the buck, Travis!
     Travis (meek and proud at the same time): It's what I do. It's who I am.
     Pamela: Even with 75 stellar masses of material in the region, the newborn star won't be 75 times the mass of the Sun. During the star formation process immense mass loss will occur as winds from the young star blow away material.
     Travis: Astronomers don't know exactly how large stars can get. Estimates vary wildly and there are sometimes heated debates over it. The Pistol Star is regarded by some as the most massive star in the sky and may be 100 times as massive as the Sun. 
     Pamela: However, both it and Eta Carinae - a star that challenges it for the #1 spot, could actually be many stars hanging out closely together. So no one really knows how large a single star can get.
     Crowd: Hey, hey, ho, ho. Slacker Astronomy must go! Hey hey, ho, ho, Travis's voice really blows!
     Travis: That's it. They're getting personal now. Get my gun, I'm going postal UT Austin style.
     Pamela: Relax! It will be hard to do this show from behind bars.
     Travis: I don't plan on being taken alive.
     Pamela: It will be even harder to do it from the grave.
     Travis: Good point. Okay, get the water balloons. I'll get the vinegar.
     Pamela: Let it go! Just turn the other cheek.
     Travis: Good idea! Open the window. 
     (zipper sound)
     Pamela: Travis!
     Travis: It's about time we did a show about the Moon!
     Pamela: If those pants drop then I'm joining the protestors outside!
     Travis: You're so square, Pamela. (snotty) You've changed.
     Pamela: Three restraining orders will do that to you. 
     Travis: Thanks for listening to Slacker Astronomy. Show notes are on our web site at slackerastronomy.org. Remember to tell your friends and enemies and Myspace addicts. Word of mouth is the best marketing tool.
     Pamela: For our author Aaron, he's Travis and I'm Pamela. 
     Travis: Clear skies and clear bandwidth. This has been Slacker Astronomy, a podcast for you, for fun, for the voices in our heads.