The LCROSS satellite, launched on June 18th, is slowly making itself ready to smack into the moon in late October. A plume of dust 37 miles high will be produced, which may be visible from Earth (most likely Hawaii). The envy of the Mythbusters, this explosion is designed to find water in permanently shadowed areas of the moon. Much has been written on LCROSS, from historical perspectives to cost containment.
As the impact grows closer, NASA is making an effort to talk about the locally driven mission. Many of the upcoming talks are suitable for any audience, from kids to adults.
Details: Dr. Kim Ennico, LCROSS Payload Scientist and the LCROSS Payload Integration & Test Manager, will provide an overview of the NASA LCROSS mission and discuss how NASA has been expanding the concept of “participatory exploration” with LCROSS as an example. This will be a lively discussion. Andrew Chaikin on LCROSS
Details: Author, speaker, and space journalist Andrew Chaikin joins Chabot visitors for a night of moon conversation and exploration. Using the detailed program Google Moon, which he helped to develop, Chaikin takes the visitor on a guided tour of the moon’s surface. Chaikin will also discuss the recent LCROSS mission and his extensive knowledge of the Apollo missions.
Details: Take a trip to our nearest neighbor in space with renowned science journalist and space historian Andrew Chaikin. Relive the achievements of Apollo lunar astronauts and learn about the ambitious LCROSS mission, which will send a rocket crashing into the moon’s permanently shadowed regions to kick up huge plumes of debris in the hopes of uncovering deposits of ice. In addition, Exploratorium educators will give an entertaining and interactive overview of moon science.
The Hubble Space Telescope being serviced by Space Shuttle Atlantis astronauts in May 2009. Credit: NASAFour hundred years ago, Galileo built his telescope and became the first on record to point the new device (invented the previous year) at objects in the sky. Today (in fact, even as I write!) what has become a symbol for the current state of evolution of the telescope—the Hubble Space Telescope–is being repaired and upgraded by the crew of the Space Shuttle Atlantis…for the last time.
Galileo's telescope had a magnification of only about 27x, allowing him to see that Venus has phases like the Moon, Jupiter has four large moons of its own, Saturn does not appear as a simple disk but has unusual "projections" to either side, and the Milky Way contains far more stars than is apparent to the naked eye. And though these are features that can be seen through the least powerful home telescopes today, Galileo's observations changed the way we look at the universe.
Hubble has done the same thing, but on a modern scale of magnitude. Not a large telescope by the standards of ground-based behemoths like Keck in Hawaii (Hubble's primary mirror is 2.4 meters in diameter), Hubble's "edge" is it's location in space, orbiting the Earth over 300 miles high, outside of our atmosphere. Particularly in its earlier days before ground based telescopes were using adaptive optics techniques to compensate for atmospheric distortion, Hubble's vision on the universe was unparalleled in its clarity.
Here's is a recap of a few of the many big discoveries Hubble has made possible:
Dark Energy: By accurately measuring the distance and velocity of distant supernovae, over a large range of distances, Hubble has refined out knowledge of the rate of expansion of the universe–leading to the discovery that the expansion of the universe is actually accelerating, contrary to what was expected. Scientists suggest the existence of a mysterious "dark energy" throughout the universe that exerts an antigravitational repulsive pressure on the cosmos.
Age of the Universe: Since Edwin Hubble (for whom the Space Telescope was named) discovered that the universe is expanding, astronomers have been trying to determine how long ago the expansion began–how long ago the "starting gun" of the Big Bang was fired, and thus the beginning of the universe. Through precise observations with the Hubble, astronomers in recent years have been able to peg it between 12 and 14 billion years. (Most recently, observations made with the WMAP mission have honed that down to 13.7 billion years, give or take 0.13 billion.)
Supermassive Blackholes: Hubble found the clues that point to the existence of "supermassive" blackholes at the heart of maybe most–or every–galaxy. The Milky Way's own central blackhole has a mass equivalent to four million Suns.
Stellar Dust Disks: Before the first extrasolar planets were actually detected, Hubble observations revealed that flat disks of dust encircling young and developing star systems–aka "protoplanetary disks"–is commonplace. This has given us a glimpse at what our own solar system may have looked like before the planets formed.
It has been seven years since the last Hubble servicing mission, with another servicing scheduled a few years ago cancelled in the wake of the Columbia disaster. Several failing systems will be repaired or replaced this time, and other instruments are receiving upgrades that will make Hubble more powerful than ever in its declining years.
This mission to service the Hubble will be the last. Since NASA is retiring the Space Shuttle fleet after 2010, we will no longer have a space vehicle large enough to carry upgrade and replacement equipment to and from the Hubble. After that, the next new big space-based descendent of Galileo's spyglass will be the James Webb. Stay tuned…
Cal Poly's CP-4 mini-satellite in orbit. Credit: The Aerospace
Corporation.
It's a classic engineering story – a garage inventor spends years working in isolation, only to produce something that gets the attention of the world. Ok, the CubeSat story may not be quite as romantic, but it does have a lot of the same ingredients.
Professors at Stanford University and Cal Poly created CubeSats – 10 by 10 by 10 centimeter mini-satellites – as enginneering projects to give their students hands-on experience. Compared to standard satellite missions, which can run hundreds of millions of dollars and take years to complete, CubeSat missions are mean to be done cheaply and quickly.
CubeSat is also a standard – a basic blueprint that any university program can use. CubeSats are actually known as "FedEx satellites," since universities can mail them to Cal Poly to arrange a ride into space. They've created launching devices called P-Pods (a box that fits the CubeSats perfectly) so they can piggyback on larger rocket launches. Once the main cargo is deployed, the P-Pod releases the CubeSats into orbit. Depending how high they are, CubeSats can orbit for more than a decade before they burn up in the atmosphere.
What started at universities has spread – NASA, Boeing and other aerospace companies all have mini-satellite programs. Despite the small size, CubeSats are actually able to do valuable research. They can space test new technology, submitting it to all the rigors of space travel like solar radiation and launch stress. Recreating those conditions on the ground can be very expensive.
CubeSats can also gather scientific data. On Tuesday, NASA will be launching Pharmasat, which they hope will be their second nano-satellite in orbit. It will carry yeast samples, and once in orbit will hit them with an anti-fungal to see if their resistance is increased in space. NASA has previously observed that some bacteria are more resistant to antibiotics in space, something that could be dangerous for future human space travel.
Star or Comet?Yesterday was a very long day at work. I was stuck in meetings with our collaborators for over 6 hours! To make it worse, we spent the entire time discussing a single topic. I even wrote my last paper on it. What could possibly be so captivating, you ask?
Remember the solar windI wrote about a few weeks ago? This stream of protons does more than create comet tails and aurora, it also destroys all of those fancy electronics we work so hard to put into orbit.
The protons streaming from the sun carry a lot of energy, and they leave a lot of this energy behind as they pass through satellites and astronauts that don’t have the Earth’s atmosphere to protect them. The energy released wrecks havoc on the system, throwing electrons and atoms around like a game of ping-pong. This is one form of radiation damage.
Definitely a comet!
This radiation damage is harmless over short periods of time, much like an occasional X-ray at the dentist. However the solar wind becomes a problem for something like the Hubble Space Telescope or our proposed satellite SNAP which are exposed for many years.
To understand how a telescope degrades from exposure to radiation, let me give an extremely quick explanation of how we gather astronomical images. A telescope is very similar to a camera you buy in the store. The large mirror is equivalent to the lens on your camera. The part that suffers the most radiation damage is the Charge Coupled Device, also known as a CCD.
The CCD is essentially the same as the 8-megapixel chip in your digital camera. This serves as an electronic version of film, recording the image through the photoelectric effect rather than through a chemical reaction. If you can still remember how photography was in the days of film, I'm sure you can appreciate the relief of going digital. Astronomers realized this early on and were pioneers in the use of CCDs.
The photons from the subject of the photograph collide with electrons in the silicon of a CCD, knocking them free from their parent atom. The free electrons are then collected in a well near the site of the collision. Once the exposure is complete, charge is moved one well (or pixel) at a time toward a transistor which then reports the number of electrons found. This process is usually described through the analogy of a bucket brigade passing buckets of water from a reservoir to a fire.
When the CCD is brand new, the bucket brigade performs almost perfectly. If I want to observe a star, the image comes out crystal clear. However, after enough time in space and in the solar wind, the CCD begins to show its wear. The bucket brigade gets sloppy at work and has to contend with an increasingly difficult obstacle course, spilling a little bit of water (or electrons) during each transfer. That same star now leaves a trail of charge behind and begins to look more like a comet.
Now, if I am observing a star, I want my image to look like a star, not like a comet. Is that really too much to ask? Unfortunately, the CCD will inevitably deteriorate in space and astronomers have to find ways to predict and correct for this deterioration. This is what we spent yesterday discussing. We passed around some pretty good ideas but still have a bit of work to do before we can prove a new method for correcting the images. I just hope we it figured out before our satellite launches in 2015!
Kyle S. Dawson is engaged in post-doctorate studies of distant supernovae and development of a proposed space-based telescope at Lawrence Berkeley National Laboratory.
The QUEST Community Science Blog explores local science, nature, and environment issues & experiences in Northern California. A collaborative effort, our many writers come from local museums, zoos, science centers and research institutions, as well as KQED's TV and Radio producers covering stories in the field.
The LCROSS satellite, launched on June 18th, is slowly making itself ready to smack into the moon in late October. A plume of dust 37 miles high will be produced, which may be visible from Earth (most likely Hawaii). The envy of the Mythbusters, this explosion is designed to find water in permanently shadowed areas of the moon. Much has been written on LCROSS, from historical perspectives to cost containment.
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The Hubble Space Telescope being serviced by Space Shuttle
Star or Comet?
Definitely a comet!
