Podcaster: Morgan Rehnberg
Title: Monthly News Roundup: Reuse and Recycle
Link : http://cosmicchatter.org
ISEE 3: https://en.wikipedia.org/wiki/International_Cometary_Explorer#Reboot_effort
Description: Two spacecraft get new leases on life. A new simulation promises to shed light on the history of our Universe. It’s been fifty years since a great astronomical discovery.
Bio: Morgan Rehnberg is a graduate student in astrophysics and planetary science at the University of Colorado – Boulder. When not studying the rings of Saturn, he develops software to help search for asteroids that might hit the Earth. He blogs and podcasts about astronomy and space science at http://cosmicchatter.org.
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You’re listening to the 365 Days of Astronomy for May 31st, 2014. I’m Morgan Rehnberg and this is the Monthly News Roundup. This episode was produced May 28th in Boulder, Colorado.
Our top story this month is the attempted restart of the ISEE 3 spacecraft. Launched in 1978, ISEE 3 was part of a revolutionary constellation of spacecraft designed to monitor the solar wind emanating from the Sun. Following four years of successful observations, the spacecraft was repurposed to study comets. During this time, the ship made close encounters with Comet Giacobini-Zinner in 1985 and Comet Halley in 1986.
By 1991, ISEE 3 had yet another mission: monitoring coronal mass ejections from the Sun. It continued to serve this purpose until 1997, when NASA determined that further operating the mission would cost more money than the returned science was worth. The spacecraft was ordered to be shut down, save for a faint beacon to help track its location.
More than ten years later, however, it was discovered that the order to shut down was never actually transmitted to ISEE 3. Twelve of its thirteen instruments were still functioning thirty years after its launch. Although NASA is still uninterested in funding operation of the spacecraft, a lot has changed since 1997.
Now, fourteen years after its mission was terminated, a group of citizen scientists has used the internet to raise nearly $160,000 to give the mission another breath of life. Their goal is to use the giant Arecibo radio telescope to command ISEE 3 to use its last remaining fuel to enter a stable orbit nearby to the Earth. The catch is, this maneuver will only work during a small window at the end of May and beginning of June 2014. If contact cannot be established and the maneuver isn’t executed on time, the spacecraft will be out of range for more than forty years.
This effort marks a remarkable new era of space exploration. For the first time in history, a spacecraft designed and operated by nations is being turned over to the citizens of the world for the pursuit of science. If this audacious plan succeeds, it could be but the first step in a new tradition of keeping alive our engineering marvels for the enjoyment of future generations.
How long have you ever waited for your computer to do something? A minute? An hour? Whatever the number, it’s probably less than two thousand years! So, what would two thousand years of computer crunching net you? How about a simulation of one ten-billionth of the Universe? That’s the result announced this month by the team behind the Illustris simulation.
Of course, no one has been running a computer for two thousand years, so how did researchers accomplish this feat? They used not one computer, but the eight thousand which make up one of the most powerful supercomputers in the world. This knocked the running time down to a mere three months. Not bad for fourteen billion years of simulated time!
So, can you find the Milky Way in the Illustris simulation? Not quite. In order to exactly reproduce nature as we see it, the simulation would have to be programmed with the absolutely exact conditions of the Big Bang and simulate the physics perfectly. Instead of looking for recognizable objects, scientists look to see if the simulation correctly recreates the broader qualities of our Universe. For example, the region of space simulated by Illustris formed the proper ratio of spiral and elliptical galaxies and populated them with the proper mix of chemicals.
But if this simulation doesn’t match the world we see, what can we use it for? One valuable role it will play is in determining how familiar objects formed. If, for example, astronomers discover a strange looking spiral galaxy out in space, they can look for a similar galaxy in the simulation and then wind back time to see how it might of formed. The simulation will also help scientists understand how small changes early in the history of the Universe can percolate down to the present time.
As our computers become more powerful and our simulation techniques more advanced, projects like Illustris will increasing provide supporting evidence for theories about how the cosmos works.
It was a year ago this month that NASA’s Kepler mission received disastrous news: a second of the spacecraft’s four reaction wheels was broken. Basically fancy gyroscopes, reaction wheels are vital to all rotationally-stabilized spacecraft. A separate wheel is required for each axis, meaning that three must be operational at all times. With Kepler down to two, the satellite’s aim would slowly drift across the sky. No mission has ever relied on exquisitely accurate aim as much as Kepler, so this was a crushing blow to its planet-finding aspirations.
With NASA’s limited budget, a crippled Kepler was an obvious target for shutdown, but this month scientists received word that the ailing spacecraft would instead be repurposed. With an unparalleled ability to measure tiny variations in light, Kepler still has a lot to offer. But, how will the spacecraft be stabilized?
To solve this problem, engineers relied on the one thing that space is full of: light. Light has one of the most remarkable properties in nature. Even though it weighs exactly nothing, it still carries momentum and exerts pressure. This incredible fact is a result of Einstein’s famous E = mc squared equation. Because light carries solar energy, it must also exert a force. By properly aligning the now-unstabilized axis of Kepler with the light pressure from the Sun, the spacecraft can essentially lean against light for balance.
So, will Kepler be able to continue its planet-hunting mission? Sort of. Because of the novel approach needed for stabilizing the satellite, Kepler will no longer be able to stare continuously at the same patch of sky for years on end. Instead, it will study several different patches, each for about two and a half months. This will enable the mission to continue to discover planets with very short periods, but no longer will it find Earth-like planets. The telescope will also now be used to study supernovae and solar system asteroids.
It’s often said that necessity is the mother of invention and that’s certainly true here. When faced with the loss of one of its most successful telescopes, NASA stepped up and found a novel way to keep it alive. And, with resources scarce, nothing could be more important than that.
Finally this month, the fiftieth anniversary of one of astronomy’s greatest discoveries. Today we take for granted that the Universe began with the Big Bang, an explosion of matter, energy, space, and time more than thirteen and a half billion years ago. But, it took one of history’s most remarkable chance discoveries to lend the Big Bang theory the credence it has today.
The year was 1964. Arno Penzias and Robert Wilson were working at legendary Bell Laboratories to develop microwave-based communications systems. Using one of the most sensitive radio receivers in the world, the two men were attempting to listen for signals bounced off of airborne balloons. What they heard instead was a lot of noise. Systematically, they worked to eliminate possible sources of this noise. They screened out air traffic control radar and blocked the frequencies used by local radio stations. Using liquid helium, they cooled their instrument down to just four degrees above absolute zero. They even scrubbed bird droppings off the system. One source of noise persisted.
Most puzzling, this source was absolutely constant. No matter where they pointed their antenna, day or night, the noise was exactly the same. They ruled out the Earth, the Sun, and even the Milky Way as the source of this remaining noise. It must, they concluded, come from beyond our galaxy. It didn’t take too long for them to hear about certain predictions made by the fledgling Big Bang theory. They obtained an advance copy of an upcoming paper detailing these ideas. Their observations matched exactly. This mysterious noise in their receiver was the first light that could travel after the Big Bang. It would take just fourteen years for the two men to receive the Nobel Prize in physics.
In the fifty years since its discovery, the cosmic microwave background, as the noise came to be called, has become among the most studied phenomenon in astronomy. Today we’ve measured its mean temperature at 2.72548 degrees above absolute zero. As our observations became more sensitive, scientists began to notice tiny deviations from this mean. Today, cosmology tells us that these variations in the early moments of the cosmos grew to become the galaxies, stars, and planets we see today.
Like the discovery of penicillin fewer than forty years earlier, the discovery of the cosmic microwave background is a towering testament to the value of careful observation in science. Flemming, Penzias, and Wilson could have easily overlooked small irregularities in their experiments. Instead, they tracked them down and uncovered incredible new aspects of nature. It’s tantalizing to think of how many other chance discoveries we may have overlooked. So, if you’re a scientist out there, next time something behaves strangely, don’t just throw it away. A Nobel Prize might be your reward.
Thanks for listening to this episode of the Monthly News Roundup. For more astronomy news and commentary, visit http://cosmicchatter.org or follow us at @cosmic_chatter on Twitter. As always, we welcome your comments and corrections at firstname.lastname@example.org. See you in June!
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365 Days of Astronomy
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