Donald Yeomans

With the recent discovery of the amino acid glycine in the comet dust samples returned to Earth by the Stardust spacecraft, it is becoming a bit more clear how life may have originated on Earth. Water is a well-known ingredient in both comets and living organisms, and now it appears that amino acids are also common to comets and living organisms. Amino acids are used to make proteins, which are chains of amino acids, and proteins are vital in maintaining the cell structures of plants and animals.

Amino acids had previously been identified in meteorite samples, and these samples are thought to be the surviving fragments from asteroid collisions with the Earth. So now it appears that both comets and asteroids in the Earth’s neighborhood, the so-called near-Earth objects, delivered some of the building blocks of life to the early Earth.

Asteroid Eros - Mosaic of Northern Hemisphere. Image Credit: NASA/JPL/JHUAPL
› Full image and caption

Impacts of comets and asteroids with the early Earth likely laid down the veneer of carbon-based molecules and water that allowed life to form. Once life did form, subsequent collisions of these near-Earth objects frustrated the evolution of all but the most adaptable species. The dinosaurs checked out some 65 million years ago because of an impact by a six mile-wide comet or asteroid off the coast of the Yucatan peninsula. Fortunately, the small, furry mammalian creatures at the time were far more adaptable and survived this impact event. Thus, present day mammals like us may owe our origin and current position atop Earth’s food chain to these near-Earth objects, one of which took out our dinosaur competitors some 65 million years ago.

Today, most of the attention directed toward near-Earth objects has to do with the potential future threat they can pose to life on Earth. However, the recent Stardust discovery of a cometary amino acid reminds us that, were it not for past impacts by these objects, the Earth may not have received the necessary building blocks of life, and humans may not have evolved to our current preeminent position on Earth. While giving thanks to these near-Earth objects, we still need to make sure we find the potentially hazardous comets and asteroids early enough so we don’t go the way of the dinosaurs.

For more information on near-Earth objects, see: http://www.jpl.nasa.gov/asteroidwatch/index.cfm

Glenn Orton

We’ve had such great feedback and comments to our earlier post about the recent impact at Jupiter that we wanted to give you more details, plus answer some questions. My name is Glenn Orton, a senior research scientist at JPL. My colleague and fellow JPL blogger Leigh Fletcher is on a well-deserved vacation for a bit, and he filled in for me while I was at a conference talking about another aspect of our research and the Jupiter impact last week.

I’ve been on Anthony Wesley’s email list (as I am for many in the amateur astronomy community) for some time, so it wasn’t happenstance that I was aware of his Jupiter observation. Anthony is the Australian-based amateur astronomer who alerted the world to this big impact. When we received news of his discovery, we immediately wanted to verify it with some of the sophisticated telescopes NASA uses. Having actively observed in both the visible and infrared during the Shoemaker-Levy-9 impacts in 1994, I was aware that a quick verification was possible by looking at a wavelength with lots of gaseous absorption, which suppresses light reflected from Jupiter’s deep clouds.

This image shows a large impact shown on the bottom left on Jupiter’s south polar region captured on July 20, 2009, by NASA’s Infrared Telescope Facility in Mauna Kea, Hawaii. Image credit: NASA/JPL/Infrared Telescope Facility

Luck was on our side. Several months before the impact, our JPL team had been awarded observing time on NASA’s Infrared Telescope Facility (IRTF) atop Mauna Kea in Hawaii. We had the midnight to 6 a.m. shift (from our Pasadena office, which meant we started work at 3 a.m.) so much of our observing time would take place before Jupiter rose over Australian skies. Another piece of luck is that Anthony’s “day job” involves software engineering so he was able to watch the same telescope instrument status and data screens as we were, while we did remote-style observing from the IRTF over the Internet. He would also be doing his own (now *very important*) post-impact observing. Weather was just as “iffy” over Mauna Kea as in Australia, so it was lucky for all of us that we could catch this event.

With Leigh, several JPL summer interns and me huddled at our side-by-side computers at JPL (one with instrument controls and one showing the data), and Anthony online from Australia, we got started. We knew the location of Anthony’s dark spot would be coming over Jupiter’s rising limb (edge) just as our allotted time was beginning. A near-infrared spectrometer was in the center of the telescope from the previous observer. Although it wasn’t our instrument of choice (we wanted images!), it has a very nice guide camera sensitive to the near infrared, so we used it rather than waiting for the 20-40 minute hiatus needed by the telescope operator to move it out of the way and put our preferred instrument in its place. This turned out to be a good decision because the very first image showed us something brighter than anyplace else on the planet — exactly where Anthony’s dark feature was located. For me, this totally clinched the case that this was an impact. Even better was the fact that Anthony was looking on in real time. We e-mailed him what was obvious - he was *definitely* the father of a new impact!

Right after this we collected data that may help us sort out any exotic components of the impactor or of Jupiter’s atmosphere and just how high the particulates have spread. Then we switched instruments to something at much longer wavelengths that told us the temperatures were higher, and that ammonia gas had probably been pushed up from Jupiter’s troposphere (the lower part of the atmosphere) and ejected into its stratosphere (higher up in the atmosphere). We finished up with our preferred (more versatile) near-infrared camera and ended up, pretty tired, at 9 a.m. (this was a midnight to 6 a.m. run in Hawaii, and in California we were three hours ahead). Then we took some of the screen shots we’d been making and used them to submit a press release. Another person had already alerted a clearinghouse for important astronomical bulletins, so that was another thing that was important but that we didn’t need to do.

Now some responses to posts:

Good post from Mike Salway who is another one of the cadre of the world’s talented Jupiter observers. I should note that, in fact, there aren’t all that many of us who track the time evolution of phenomena in the planets in the professional community, either (see the web pages for the International Outer Planet Watch: http://dawn.ucla.edu/IJW/).

Asim. Neither NASA nor JPL is capable of observing everything in the sky. There is a program to search for asteroids whose orbits will intersect the Earth’s, but not at Jupiter. In fact, it’s unlikely this object could have been seen, given that it may have been at most a half kilometer in size. For Shoemaker-Levy 9, we were both lucky and the disruption of the comets left a lot of very shiny material around it which made it easier to see.

Denise. It hit quite a bit further south than the Shoemaker-Levy 9 fragments, almost at 60 deg S latitude.

Patrick, Jim, BobK. I suspect that the only link between this and the SL9 fragments is the voracious appetite of Jupiter, the great gravitational vacuum cleaner in that part of the solar system! SL9 fragments impacted from the south; this was from the east.

Leigh Fletcher

What an incredible few hours it’s been for astronomers everywhere, as we witness a chance of a lifetime event: evidence of a space rock of some sort slamming into Jupiter. Images taken after the impact show the debris field and aftermath of a gigantic collision that occurred in the southern polar region of the enormous planet.

An extremely dedicated and meticulous team of amateur astronomers observe Jupiter’s changing cloud patterns on a regular basis, and it came as an amazing surprise when Anthony Wesley, near Canberra, Australia, reported his Sunday-morning (July 19, 2009) observations (http://jupiter.samba.org/jupiter-impact.html) of a dark scar that bore all the hallmarks of the Shoemaker Levy 9 impacts at Jupiter in 1994. By an amazing coincidence, I was part of a team that had already been allocated time to observe Jupiter from the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. Based on Anthony’s discovery, we were crowded around our computers at 3 a.m. PDT (with Anthony observing with us remotely from Australia) as the first near- and mid-infrared images started to come in… it was such an exciting moment, seeing the high altitude particles that had been lofted by the impact (they appear bright in the infrared). Anthony celebrated with us, but then the real work began. We celebrated and then rolled up our sleeves and began an exciting night of observations.

This image shows a large impact shown on the bottom left on Jupiter’s south polar region captured on July 20, 2009, by NASA’s Infrared Telescope Facility in Mauna Kea, Hawaii. Image credit: NASA/JPL/Infrared Telescope Facility

With the assistance of William Golisch at the IRTF, Glenn Orton and I viewed the impacts in as many wavelengths and spectra as we possibly could, as Jupiter rotated and carried the impact scar out of Earth’s view. We used these many views to show evidence for high temperatures at the impact location, and suggestions of ammonia and aerosols that had been carried high into the atmosphere. The observations were repeated again today, Tuesday morning, to track the shape and properties of the site. The scar is extremely large, almost as big as Earth and will continue to grow as Jupiter’s atmospheric winds and jet streams redistribute the material, and then, like Shoemaker-Levy 9, it will begin to fade in the coming weeks and months. Based on comparisons to SL-9, the impactor was likely to be small despite the large aftermath, maybe a few hundreds of metres across. Not only will this tell us a lot about impacts in the outer solar system, and how they contribute to the nature of the planets and icy moons, but they’ll also serve as a probe for the fundamental weather patterns in Jupiter’s high atmosphere.

Amateur observers continue to flood the Internet with new images of the dark spot at approximately 60 degrees south on Jupiter, and so far it looks as though the impact took place sometime in the 24 hours preceding Anthony’s discovery. The debris field now extends out to the west and northwest, with additional high-resolution images from the Keck telescope (Marchis, Wong, Kalas, Fitzgerald and Graham http://keckobservatory.org/index.php/news/jupiters_adds_a_feature/) showing the detailed morphology of the impact region. The hard work continues today, as an international team of planetary astronomers scrambles for time on some of the world’s largest astronomical facilities.

Finally, it’s a shame but perhaps not surprising that we didn’t see the collision, or the impactor itself, given the great distance to Jupiter. Like throwing a rock in a pond, we’re seeing and analyzing the splash that it’s made, and we can’t yet infer many details about the rock itself - the detailed shape of the impact site could help determine the trajectory and energy of the collision. But it certainly made quite a splash, and we hope to learn a lot about Jupiter from this event!

Anthony’s discovery is truly astounding, as it united astronomers in looking again at the gas giant Jupiter. It’s overwhelming and spectacularly exciting to watch this event unfolding before our eyes!

You can follow Leigh on Twitter at http://twitter.com/LeighFletcher

Bjorn Lambrigtsen

JPL scientist Bjorn Lambrigtsen goes on hurricane watch every June. He is part of a large effort to track hurricanes and understand what powers them. Lambrigtsen specializes in the field of microwave instruments, which fly aboard research planes and spacecraft, penetrating through thick clouds to see the heart of a hurricane.

While scientists are adept at predicting where these powerful storms will hit land, there are crucial aspects they still need to wrench from these potentially killer storms.

Here are thoughts and factoids from Lambrigtsen in the field of hurricane research.

1. Pinpointing the moment of birth

Hurricane Gustav moved along the southern side of Jamaica on Aug. 29, 2008. Image credit: NASA MODIS Rapid Response

Most Atlantic hurricanes start as a collection of thunderstorms off the coast of Africa. These storm clusters move across the Atlantic, ending up in the Caribbean, Gulf of Mexico or Central America. While only one in 10 of these clusters evolve into hurricanes, scientists do not yet know what triggers this powerful transformation.

Pinpointing a hurricane’s origin will be a major goal of a joint field campaign in 2010 between NASA and the National Oceanic and Atmospheric Administration (NOAA).

2. Predicting intensity

Another focus of next year’s research campaign will be learning how to better predict a storm’s intensity. It is difficult for emergency personnel and the public to gauge storm preparations when they don’t know if the storm will be mild or one with tremendous force. NASA’s uncrewed Global Hawk will be added to the 2010 research armada. This drone airplane, which can fly for 30 straight hours, will provide an unprecedented long-duration view of hurricanes in action, giving a window into what fuels storm intensity.

3. Deadly force raining down

Think about a hurricane. You imagine high, gusting winds and pounding waves. However, one of the deadliest hurricanes in recent history was one that parked itself over Central America in October 1998 and dumped torrential rain. Even with diminished winds, rain from Hurricane Mitch reached a rate of more than 4 inches per hour. This caused catastrophic floods and landslides throughout the region.

4. Replenishing “spring”

Even though hurricanes can wreak havoc, they also carry out the important task of replenishing the freshwater supply along the Florida and southeastern U.S. coast and Gulf of Mexico. The freshwater deposited is good for the fish and the ecological environment.

5. One size doesn’t fit all

Hurricanes come in a huge a variety of sizes. Massive ones can cover the entire Gulf of Mexico (about 1,000 miles across), while others are just as deadly at only 100 miles across. This is a mystery scientists are still trying to unravel.

NASA and NOAA conduct joint field campaigns to study hurricanes. The agencies use research planes to fly through and above hurricanes, and scientists collect data from NASA spacecraft that fly overhead. NOAA, along with its National Hurricane Center, is the U.S. government agency tasked with hurricane forecasting.

For more information on how NASA and JPL study hurricanes, go to www.nasa.gov/hurricane and http://tropicalcyclone.jpl.nasa.gov

Angelle Tanner

Angelle Tanner, a post-doctoral scholar at JPL and Caltech, studies planets in distant solar systems, called extrasolar planets. The golden prize in this field is to find a planet similar to Earth - the only planet we know that harbors life. While more than 350 extrasolar planets have been detected, most are gas planets, with no solid surface. Many are located in orbits closer to their parent star than Mercury is to the sun. In other words, not very similar to Earth.

Here’s Tanner’s short list of what she and her colleagues would love to find in another planet - the elements that might enable life on another world. With the powerful tools scientists have now and with new technology and missions coming soon, the odds are going up for finding an Earth-like planet, if one is out there.

Tanner’s top five “holy grails” of extrasolar planet research are hoped-for findings that she predicts will happen within the next 15 years.

1. First planet that weighs the same as Earth

Artist’s concept of an extraolar planet.
Image credit: NASA/JPL-Caltech

Although most planets discovered have been giant gas planets with no surface, a handful of rocky planets, called super-earths, have also been detected. Super-earths are akin to Earth in their rocky make-up, but with a mass up to 10 times that of Earth.

There is no reason these planets could not host an atmosphere or even life as we know it. The discovery of a true Earth clone – Earth-like in size and make-up — could happen within a year or two. NASA’s recently launched Kepler mission has the ability to find planets as small as Earth.

2. First Earth-sized planet in the ‘habitable zone’

The so-called habitable zone is the area around a star where a rocky planet could have the right temperature to have liquid water on its surface. In our solar system, Earth sits in the habitable zone. Venus sits just inside the habitable zone and is too hot while Mars is just outside and too cold. Finding an Earth-sized planet is this geographically desirable location is the next big step in extrasolar research. One super-earth has already been detected near to its parent star’s habitable zone and it is only a matter of time — using existing technologies –- before a planet is found in this friendly environment. Ground-based telescopes and NASA’s Kepler mission are searching stars within a few hundred light years of Earth right now.

3. First atmosphere on a rocky planet

A planet’s atmosphere, along with other factors, helps determine whether a planet could sustain life. For the past few years, astronomers have studied the atmospheres of Jupiter-like, extrasolar planets. These gas giant planets have hydrogen-rich atmospheres inhospitable to life as we know it. However, many of the techniques developed for studying gas giants could be used to study the atmospheres of super-earths. This would mark an important step in beginning to understand the environment of rocky planets.

4. First hint of habitability and life

Once astronomers have enough Earth-sized planet atmospheres to study, they will be looking for biosignatures – indicators in a planet’s atmosphere that the planet might be hospitable to or even support life. Some of the molecules they will be looking for include water vapor, methane, ozone and carbon dioxide. NASA’s James Webb Space Telescope, scheduled to launch in 2014, will provide scientists with the sophisticated instruments needed for these potential observations on super-earths orbiting small stars. Assuredly, astrobiologists will be studying such data for years to come since potential life may, or may not be, in a form we expect. Keeping an open mind is critical.

5. The unexpected

The final grail — the unexpected. The history of science is marked with findings that were never predicted. As in all fields of science and exploration, it’s what we don’t know that will be the most exciting.

For more information about extrasolar planets, visit planetquest.jpl.nasa.gov

by Sue Smrekar
Deputy Project Scientist - Mars Reconnaissance Orbiter

A theme of Mars exploration is “Follow the Water,” since understanding the history of water on our planetary neighbor will help us understand if there were environments favorable for life to occur and how climate has changed over time. This is because all life on Earth requires water and we assume the same applies elsewhere in the universe. The Mars Reconnaissance Orbiter has made numerous discoveries that have provided new insights into past wet environments on Mars, water vapor in the planet’s current atmosphere and ice in the subsurface. However, so far, liquid water remains elusive.

The Shallow Radar, or “SHARAD” instrument is the only one on the Mars orbiter that was designed with a goal of discovering liquid water below Mars’ surface. This ground-penetrating radar instrument, which was supplied by the Italian Space Agency, transmits a radar signal at approximately 20 megahertz, and receives any radar waves that bounce off the surface or subsurface layers. The radar instrument has sufficient strength to see layers to a depth of about one kilometer (a little more than one-half mile), and even deeper in the polar caps. Layers in the subsurface reflect the radar wave if there is sufficient contrast in their dielectric properties (their bulk electrical properties), as for example between dry sand and ice-filled sand. Water is a much better conductor than other geologic materials, and thus should be readily detected if present.

This image from NASA’s Mars Reconnaissance Orbiter shows gully channels in a crater in the southern highlands of Mars.The gullies emanating from the rocky cliffs near the crater’s rim (upper left) show meandering and braided patterns typical of water-carved channels. Image credit: NASA/JPL/University of Arizona

Of all the features believed to be formed by water on Mars, we have found only two gullies known to have recent flows – within the last 5-10 years. Gullies are narrow channels that emanate from cliff walls, starting well below the local ground surface. Dr. Michael Malin used the Mars Orbital Camera on Mars Global Surveyor to repeatedly image these features because of their fresh, unweathered appearance. These efforts led to the discovery of the two relatively new gullies.

To date, the Shallow Radar instrument’s observations of dozens of regions containing gullies show no evidence of liquid water. Since slopes of the cliffs where the two new gullies occur are extremely steep, some scientists put forth an alternate hypothesis in which dry debris tumbling downhill could have formed the latest channels. Yet many of the features observed at these and other gullies strongly suggest that liquid water had at least some role in carving the channels. These channels may have formed when a past climate change caused subsurface ice to melt. Or perhaps liquid water was trapped in a past aquifer. But for now, liquid water, if it exists today on Mars, remains out of reach of the Mars Reconnaissance Orbiter.

by Chris Boxe
Scientist and Engineer

Oxygen, or O2 on the table of chemical elements, is a vital component for life on Earth. It is the second most abundant gas in Earth’s atmosphere, making up about 21 percent of its volume. On the other hand, its cousin ozone (O3) makes up less than 0.00001 percent. In fact, if all the ozone in Earth’s atmosphere were brought down to the surface, air pressure and temperature conditions would compress ozone into a layer just three millimeters thick, equivalent to two pennies stacked one on top of the other. ! Despite its tiny amount, ozone is also a vital ingredient for life on Earth.

Ozone in fact is vital for life on Earth, but it also has a “bad” side as well - that is, there is both good and bad ozone out there. Good ozone, which accounts for about 91 percent of the ozone in Earth’s atmosphere, is present in the stratosphere, the middle layer in Earth’s atmosphere. This portion of ozone is commonly referred to as the “ozone layer.” The ozone layer absorbs more than 90 percent of the sun’s high-frequency ultraviolet light, which is potentially damaging to life on Earth. Without the ozone layer, this radiation would not be filtered as it reaches the surface of Earth, resulting in detrimental health effects for life on Earth. Among the health effects humans could experience as a result of overexposure to ultraviolet radiation are skin cancers, premature aging of the skin and other skin problems, cataracts and other forms of eye damage, and suppression of our bodies’ immune systems and our skin’s natural defenses.

The troposphere, the part of the atmosphere closest to Earth, contains both good and bad ozone. In the lower troposphere, ozone may serve as an air pollutant since it is a major component of photochemical smog. In the middle troposphere, ozone acts as an atmospheric cleanser, and in the upper troposphere, ozone is a greenhouse gas, which could be bad if concentrations get too high.

The Tropospheric Emission Spectrometer flies aboard NASA’s Aura spacecraft. Image credit: NASA JPL

The Tropospheric Emission Spectrometer, a science instrument onboard NASA’s Aura satellite, is improving our understanding of the good and bad ozone in the troposphere. The spectrometer, which was launched in 2004, provides the first global view of tropospheric ozone and vertical concentrations of ozone, as well as temperature and other important tropospheric features, including carbon monoxide (CO), methane (CH4), water vapor and ammonia (NH3). The instrument has studied the origin and distribution of tropospheric ozone. It has also shed light on how the increasing ozone abundance in the troposphere is affecting air quality on a global scale, as well as ozone’s role in chemical reactions that “clean” the atmosphere, and climate change.

These data are used by scientists to determine the degree to which natural sources, like lightning and plant growth, and human-produced sources, like automobiles, industrial pollution, and biomass burning, contribute to ozone production and chemistry. For example, during summertime in the upper troposphere, where ozone acts as a greenhouse gas, lightning generates much greater amounts of ozone than do human activities, thereby having a big impact on regional pollution. Over the last few years, the spectrometer has obtained global data on ozone and chemicals that participate in ozone formation. The fact that the instrument is able to quantify vertical profiles of ozone improves our understanding of how various reactions taking place at specified heights contribute to ozone chemistry. Similar to ozone, chemicals that participate in its production also exist in tiny amounts. Still, this enables scientists to better understand long-term variations in the quantity, distribution and mixing of many tropospheric gases that have a large impact on climate and air quality.

My role with the instrument is to validate the quality of the most recent ozone measurements, which are taken in a special observation mode, called “stare.” This mode is used to monitor biomass burning events and volcanic activity. I compare measurements taken by an ozonesdone (a lightweight, balloon-borne instrument that measures ozone, air pressure, temperature and humidity as it ascends through the atmosphere) with measurements from the tropospheric spectrometer. We do this so we can demonstrate the accuracy and precision of the instrument’s readings. I am also participating in projects that use the instrument data to better understand the chemistry and transport of pollutants coming from wildfires, such as those that occurred in Australia in December 2006. For the future, I am interested in using the tropospheric spectrometer satellite data for ozone and methane to better quantify the degree to which they contribute to global warming and climate change.

by Jorge Vazquez
Oceanographer

Not all oceanographers spend their time out on the seas. As a project scientist for the Physical Oceanography Distributed Active Archive Center here at JPL , I study the world’s ocean from my computer, using data from a series of NASA satellites that orbit Earth. These data measure everything from how the ocean changes during an El Nino to how such climatic changes affect local regions like California’s coast.

This kind of precise data was impossible 100 years ago. In fact, scientific and technological advances over the last century have revolutionized the field of oceanography. Today, we gather data both from instruments in the ocean and from satellites in space. These satellite data measure changes in sea surface topography (the ocean surface has changes in elevation, just like the land), ocean surface winds, sea surface temperature and water pressure at the bottom of the ocean. The satellites view the ocean from 700 to 1,300 kilometers (440 to 800 miles) above Earth. Current advanced technologies allow scientists to combine data from different satellites to view ocean conditions in near-real time, only 6 to 12 hours from when the satellite acquires the data. This information can then be sent to researchers and decision makers for use in improving forecasts for hurricanes to the regional and local impacts of ocean phenomena like El Nino and La Nina.

Image above: Sea surface temperatures in 1997 during El Nino and in 2008, when the waters had returned to more normal conditions.Image credit: NOAA

Examples of satellite data can be seen in these images. The view on the left shows temperatures off the coast of California in September of 1997 (El Nino). On the right, sea surface temperatures from September of 2008 (normal conditions). Notice the warmer temperatures (seen in red) resulting from the 1997-1998 El Nino event. Such temperature changes have direct impacts on local climate and fisheries. These data are leading to a new understanding of how hurricanes get their energy from the ocean. These satellite data also help forecast regional ocean temperatures, which affect local weather.

As technology improves, along with the availability of these data in real time, new opportunities will continue to expand to better understand our planet and its impacts on our lives.