Astronomy.com blog : Daniel Pendick, solar system

LRO scientist Michael Wyatt blogs for Astronomy

Daniel Pendick — Tue, 16 Jun 2009 19:39:00 GMT

If all goes as planned, the Lunar Reconnaissance Orbiter (LRO) will launch from Cape Canaveral either Thursday or Friday, depending on the launch of space shuttle Endeavour. Brown University professor and LRO researcher Michael Wyatt is at the launch site, and starting today, Wyatt will share his impressions of this historic mission — the opening maneuver in the United States return to the Moon — with all of you. Thanks, Michael!

We'll post Michael's updates to this article in our news section, "Exclusive: Lunar Reconnaissance Orbiter updates from mission scientist."

Your Mars questions, Dr. C answers

Daniel Pendick — Fri, 05 Jun 2009 15:33:00 GMT

The Jet Propulsion Laboratory’s Mars Exploration Program web site has a fun new feature — Ask Dr. C, “your personal Mars expert.” You can type in a simple question — the simpler, the better — and get a pretty good answer. A computer program tries to match your question with an extensive database of responses.

The real Dr. C is Phil Christensen, a planetary scientist at Arizona State University. Christensen is the Principal Investigator for the 2001 Mars Odyssey Thermal Emission Imaging System (THEMIS) instrument, and the Thermal Emission System instrument on Mars Global Surveyor.

I decided to put the virtual Dr. C through a few paces. Here’s the result.

Dr. C: Hello ... it is a great day to learn about Mars! Please feel free to ask me any questions you would like about Mars ... or even about myself.

Pendick: Does NASA really have enough money to replace the shuttle by 2014, or should we just rename the Russian space program "NASA Moscow"?

Dr. C: I am sorry, I am not sure what you are asking. You might want to try rephrasing your question, searching for it on the Internet, or visiting http://mars.jpl.nasa.gov.

Pendick: OK, fine. I’ll stick to Mars questions then. Anti-global-warming bloggers say that because the martian south pole is currently in a warming trend, this means rising global temperatures on Earth are also "natural" and not manmade. Is it just me, Dr. C, or is that the stupidest thing you ever heard?

Dr. C: I am sorry, I am not sure what you are asking. You might want to try rephrasing your question, searching for it on the Internet, or visiting http://mars.jpl.nasa.gov.

Pendick: OK! OK! I’ll throw you a bone. Here’s an easy one. Why is Mars red?

Dr. C: Mars looks red due to a combination of the fact that its surface is comprised of iron-rich minerals that essentially rust (or oxidize) and that the dust made of these minerals is kicked up into the atmosphere, giving the atmosphere a reddish hue. The Martian surface is not all rust-colored, however, because depending on the oxidation process, the minerals can be a range of colors from butterscotch to rust.

Pendick: Nice answer! So, what is the warmest it ever gets on Mars?

Dr. C: Did you mean to ask "What is it like on Mars?" or "What is Mars?"?

Pendick: No, I am asking you how warm it gets on Mars.

Dr. C: If you were asking: How warm is Mars?, the answer is: Sometimes people think Mars is hot because it is red but, due to its distance from the sun, Mars is actually very cold (its average temperature is minus 81 degrees Fahrenheit!). However, the temperature on Mars may reach a high of about 70 degrees Fahrenheit (20 degrees Celsius) at noon, at the equator in the summer.

Pendick: Just one more question for now. Do you know of an aerospace stock that will rise, say, 40 percent over the next 6 months? I need to buy a new telescope.

Dr. C: I am sorry, I am not sure what you are asking. You might want to try rephrasing your question, searching for it on the Internet, or visiting http://mars.jpl.nasa.gov.

The quiet Sun

Daniel Pendick — Fri, 03 Apr 2009 19:23:00 GMT

Last summer, my colleague Michael Bakich, a senior editor at Astronomy, kindly gave me a special filter that fits on the front of my 4-inch Celestron NexStar, thus allowing me to observe the Sun without turning my eyeball into a poached egg.

I looked at the Sun with the new setup. Nada. Nothing!

Thanks to this cool graphic just released by NASA, it’s clear why the Sun is so, well, boring to look at lately. We are in a deep “solar minimum,” a period in the 11 (or so) year sunspot cycle where things are as quiet as an umbrella shop on a sunny day.

Dramatic statistic time: As of March 31, there were no sunspots on 78 of the year's 90 days (87 percent). For more details, check out this well-done little report from Science@NASA.

Image credit: NASA/MSFC/Hathaway

WorldWide Telescope adds Mars Reconnaissance Orbiter images

Daniel Pendick — Wed, 25 Mar 2009 21:41:00 GMT

Megacorps are practically lining up for the privilege of disseminating fantastic volumes of astronomical images to you, John and Jane Q. Public.

Recently Google added a “Live from Mars” function to its 3-D visualization of Mars within Google Earth. The feature allows you to see images from the Mars Odyssey spacecraft.

Now Microsoft says it will let you explore images from the Mars Reconnaissance Orbiter (MRO, pictured at right) within its web-based astronomy application, WorldWide Telescope (WWT).

More than 100 terabytes (1 terabyte equals 1 trillion bytes) of NASA data, including images from MRO that has been studying the planet since 2006, will be incorporated into WWT later this year, according to Microsoft. Images from a camera aboard NASA’s Lunar Reconnaissance Orbiter set to launch in May will also be made available.

The inherent coolness of “Live from Mars” is that you can see new images from Odyssey’s THEMIS camera nearly as soon as scientists themselves — within a day or so, usually.

The unprocessed THEMIS images themselves are not exactly works of art. They are detailed, but in grayscale. The instrument that takes them works in infrared.

I am not aware of any plan to post MRO images “live” on WWT. But it would indeed be very cool if they did. MRO’s HiRISE camera takes stunning images.

It would be a win for us astro fans if a little healthy rivalry between Google and Microsoft spurred them to make even more NASA data available for us to explore in a user-friendly way, either in Google Earth or WWT.

Mars in Google Earth works in Windows, Macintosh, and Linux operating systems. The full-feature downloaded version of WWT works only on Windows machines right now. But WWT has recently made available a web-based version with all the major functions, and it runs beautifully on a Mac. No matter what operating system you run, you will be able to use the web version of WWT to look at the new MRO images, once they are available. (Note: To use the web-based WWT, you have to install a small plug-in called Microsoft Silverlight.)

If you are a true Marsaholic like me, you may also appreciate the Mars Express “web cam” that shows images of the Red Planet. It recently came back online after the craft emerged from behind the Sun. Check out the Mars Express Visual Monitoring Camera blog.

Exclusive: Q&A with Europa expert Richard Greenberg

Daniel Pendick — Thu, 19 Feb 2009 21:57:00 GMT

Richard Greenberg, a professor of planetary sciences at the University of Arizona's Lunar and Planetary Laboratory, is an expert in celestial mechanics and carries out NASA-sponsored investigations of solar system evolution and planet formation. He is also author of the current book Unmasking Europa.

After NASA and the European Space Agency chose Jupiter’s moons — including Europa — as the next destination for a major planetary exploration mission, Greenberg answered a few questions about the upcoming missions and his book about Europa, “an active oceanic world that just might be the most likely site for our first encounter with extraterrestrial life.”

Pendick: Are you surprised at all by NASA and ESA’s decision to go to Jupiter’s moons before going to Saturn’s moon Titan?

Greenberg: I think both proposed missions are exciting and both Europa and Titan are fantastic satellites to explore. As far as the competition for the next flagship in line, it is not a surprise that Europa was selected. It has been a top priority since the Galileo mission provided evidence for the global ocean. And the prospect for it being the place where we will most likely first find extraterrestrial life makes it an objective of almost existential significance!

That said, the discoveries about the Saturn system from the Cassini mission have shown us what active and exciting places Enceladus and Titan are. And the Titan Science Definition Team did a great job of developing a model mission that is really imaginative and spectacular.

In many ways the Titan mission is at least as appealing as the Europa one. So it is interesting that NASA did not simply make an either/or decision between the two missions — as was originally expected — but instead they made the announcement a prioritization, which leaves the door open to including the Titan mission as future budgetary and policy issues are addressed.

While I personally love Europa, for all the reasons I describe in my book Unmasking Europa, I am a big fan of the Titan mission as well.

Pendick: If you had to choose a few major points, what would you say the Europa orbiter will most likely tell us — and not tell us? For example, will the mission confirm the existence of Europa’s global ocean and perhaps how deep it is, but NOT tell us whether anything lives in it?

Greenberg: I personally believe that we already confirmed the existence of the ocean with our work on explaining the cycloidal crack patterns in terms of tidal stress and also with the Galileo magnetometer evidence. The new mission will have a laser altimeter to measure the height of Europa’s tides, and the radio tracking will also measure the gravitational effect of the tides. That information about the tides will further confirm the existence of the ocean. Contrary to some reports I have read, though, I do not believe the radio and altimeter information about the tides will tell us how thick the ice is.

There will also be an ice-penetrating radar that will tell us a lot — I hope — about the structure within the icy crust, which will help us understand the dynamics of the crust and the transport of materials between the ocean and the surface, which is critical for life, as I emphasize in my book.

The spacecraft will have a narrow-angle camera for super high-resolution imaging of Europa’s surface, in addition to wider-angle cameras. I hope the folks who plan the imaging will favor the narrow-angle camera, so we can really get a handle on the active processes that must be continually resurfacing Europa.

Other remote sensing will include an infrared spectrometer to identify the critical substances mixed in with the ice and a thermal instrument to map the heat distribution.

Naturally, if I were the king of NASA, I would order a lander to plop down selectively on a site where ocean material has recently been exposed. I could imagine finding marine organisms without needing to drill down very deep. But that is evidently something saved for a distant future mission.

Pendick: Too bad we all have to wait until 2026 to find out if you are right about Europa! But that leaves 17 years for us to read all about it in your book, Unmasking Europa. Tell us why you wrote the book and what we can learn about Europa by reading it.

Greenberg: I wanted to write this book because I knew several great parallel stories that would be fun to tell. The first was a fantastic science story about a satellite with an ocean containing twice the liquid water of all Earth’s oceans and an icy crust that is continually renewed by tectonic and thermal processing that links the ocean to the surface. Most of this information was in fragmentary form in the scientific literature, so I wanted to integrate it and make it accessible to any thoughtful reader.

Also, there had been a great deal of speculation about life perhaps being possible at imaginary volcanic vents on the ocean’s floor, but no one else was talking or writing about how the openings through the ice could really enhance the prospects for life in the ocean and that the biosphere of Europa, if any, would well extend right up to the surface.

There are also policy implications that had been under-appreciated. We may not need to drill down through the ice to reach life. It could lie very near the surface. That is the good news for exploration. The bad news, of course, is that we need to be very careful to avoid contaminating such a vulnerable place.

I also wanted to tell the story of how my own interdisciplinary research group had come to assemble this picture of a permeable ice layer by interpreting images of the surface in terms of our understanding of tides, and in the context of the wonderful scientific contributions of many other colleagues from other places.

And finally I wanted to tell the story of what I learned about the place of science in the framework of a large space mission. I wanted people to get an idea of how science really works. Like any creative human endeavor, it has its glorious aspects and its ugly ones. But it was always interesting and often hilarious. I just had to tell about it. These several story lines were interwoven and seemed to me inseparable, so that is how I wrote the book.

Europa vs. Titan: Which will NASA explore in its next flagship mission?

Daniel Pendick — Wed, 11 Feb 2009 18:11:00 GMT

“There is an ocean beneath the icy crust of Jupiter’s moon Europa [pictured at right]. Strange creatures could be swimming in these alien waters, but so far no missions have been sent there to investigate this possibility.”

So begins, "Hoping for Europa," an article by Astrobiology magazine Editor Leslie Mullen. Squids from outer space — who could resist?

Or will it be a balloon ride over the windblown surface of a hydrocarbon lake on Titan [pictured at lower left]?

“A hot air balloon drifts gently in the breeze, gliding over mountain ranges and vast lakes,” Mullen writes in another article, "Titan Triple Threat."

“Thick clouds extend over the entire horizon, threatening rain. The meager light that filters through illuminates one side of the balloon, making it look like a giant question mark in the sky.”

Later this week, NASA is expected to announce which moon of the outer solar system will be the target of a future $2 billion-plus “flagship mission.” It would likely be carried out as a partnership with the European Space Agency, along the lines of the Cassini-Huygens mission to Saturn.

The prospect of studying an alien ocean beckons. So does getting a closer look at Titan’s geologically active surface. The consensus seems to be that we are much more likely to find alien life on Europa than in the methane/ethane lakes of Titan. But who knows?

Either way, be patient. These missions would not launch before 2020 or so. If Titan gets the nod, expect a travel time of 9 years.

As soon as NASA decides, we’ll get back to you with some expert commentary.

Ho, ho, ho for Halley’s Comet

Daniel Pendick — Thu, 25 Dec 2008 01:00:00 GMT

On Christmas Day, 1758, a German amateur astronomer and farmer named Johann Georg Palitzsch did something that would have made a great Christmas gift for English astronomer Edmond Halley. Johann “recovered” Halley’s Comet, meaning he was the first to observe this previously observed “dirty snowball” as it returned to the inner solar system.

Edmond Halley (1656-1742) calculated the orbit of the comet that now bears his name based on previous sightings. He determined that the same comet was responsible for several sightings spaced about 75 years apart.

By Halley’s reckoning, the comet would reappear in 1758 — that’s 250 years ago this Christmas. Unfortunately, he didn’t live to see his prediction proved correct.

For the complete and detailed scoop on the recovery of Halley’s Comet, read this treasure-trove of information and images by master comet observer Gary W. Kronk, author of the Cometography book series.

Enceladus ice tectonics: Cassini’s latest mind-blowing image of another world

Daniel Pendick — Wed, 17 Dec 2008 19:36:00 GMT

Many phases of the Moon ago — more than 200 — I came under the spell of earth science and wrote a lot about it for a number of years. This week, some of that ancient knowledge came back to visit as I gazed at a fantastic 28-image mosaic of Saturn’s moon Enceladus.

You may see crusty cracked ice; I see the outlines of ice continents.

At the American Geophysicial Union meeting in San Francisco this week, the halls are abuzz with talk of plate tectonics on Enceladus.

Using Cassini-based digital maps of the south polar region of Enceladus, Paul Helfenstein of Cornell University in Ithaca, New York, reconstructed a possible history of the famous “tiger stripe” features by working backward in time and progressively snipping away older and older sections of the map. Each time he found that the remaining sections fit together like puzzle pieces. Bottom line: Giant fragments of Enceldus’ crust ARE MOVING.

In the 20th century, earth scientists found evidence for plate tectonics on Earth in part by reassembling puzzle pieces of Earth’s crust delineated by cracks in the seafloor called plate boundaries.

At some boundaries, tectonic plates scrape past each other; at other boundaries, plates nose under a neighbor or crash straight into each other, raising great mountain ranges like the Himalayas.

The same process is happening on Enceladus. This implies that energy is flowing somewhere underneath all that ice — probably heat convection similar to the swirling flow ina boiling pot.

Exobiologists think that where some sort of “energy gradient” exists — a difference between warm and cool, for example — life can develop. In the 1970s, biologists stumbled on diverse ecosystems thriving at plate tectonic boundaries on the seafloor. Hot hydrothermal water and elements like sulfur were all they needed to live in the inky darkness.

Oceans of water lie beneath the crust of Encaladus. The region near its famous geysers is warmer than its surroundings — an energy gradient if ever there was one. And the geyser jets contain organic molecules.

If we could drill beneath the icy continents of Enceladus — like the pilots of the deep-sea submersible Alvin visiting hydrothermal vent ecosystems — what might we find there?

Picture thick mats of bacteria coating cracks and crevices in the hydrothermal systems in Enceldaus crust.

It’s the stuff of science fiction, but could come true in our lifetimes.

Animation of Chandrayaan-1 flight to the Moon

Daniel Pendick — Thu, 06 Nov 2008 15:22:00 GMT

India’s Chandrayaan-1 lunar probe will fire a rocket Saturday, November 8, to insert itself into orbit. As I sat down to prepare a magazine news article about the mission earlier this week, I found myself lacking a decent piece of space art of the probe. A web search led me not to the Indian Space Research Organisation (ISRO), which lofted the craft, but to a talented space enthusiast in England named Doug Ellison. He kindly provided the image of Chandrayaan-1 you will see in a future issue of Astronomy in the “Astro News” section.

Doug describes himself as a multimedia producer covering animation, filming, editing, media management, and DVD production for a medical e-learning company in the United Kingdom. He also claims to be “dictator for life” of the excellent web site unmannedspaceflight.com, a forum on the Internet for discussing — you guessed it — things that fly through space without people in them. Like Chandrayaan-1.

Through his interest in space science, Doug ended up producing a gorgeous computer animation of the Chandrayaan-1 flight to the Moon (warning: it took us a long time to load the movie, but it was well worth the wait) and its deployment of the C1XS X-ray spectrometer built by the UK’s Rutherford Appleton Laboratory (RAL). He got to visit the RAL as part of the project and scrutinize the instrument in the facility’s high-tech clean room.

Cost to RAL and ISRO? Zero. He also provided a still shot of the animated sequence to us — again, no cost.

It seems he did it for the fun of it. This is just another of many examples we see every day of enthusiasts donating their time and many talents to promote amateur astronomy and space science. Remember, the French word amateur derives from the Latin amātor, or “lover,” from amāre, “to love.”

From asteroid to fireball — in a day

Daniel Pendick — Mon, 06 Oct 2008 21:52:00 GMT

If you want to witness something historic, get on the next flight to Sudan. That’s where a unique meteorological event may take place late tonight.

Astronomer Rich Kowalski of the Catalina Sky Survey in Tucson discovered asteroid 2008 TC3 last night. And astronomers predict that tonight, on October 7 Africa time, the object will enter Earth’s atmosphere and burn up in a spectacular fireball.

The asteroid is only a few meters across at most, so it will not reach the surface and thus poses no threat to anybody. (Whew!) But it’s big enough to put on an impressive show — I mean, if you live in Sudan.

According to Don Yeomans of the Near-Earth Object Office at NASA's Jet Propulsion Laboratory in Pasadena, California, this "is the first time we have observed an impacting object during its final approach."

Pretty amazing story — the space rock that (maybe) will go from asteroid to a hot smudge on the upper atmosphere in only 2 days!

For more information about this event, read Senior Editor Rich Talcott's preview, "Asteroid will disintegrate in Earth's atmosphere tonight."