Prelaunch Preps Continue at Kennedy and Johnson

Final system checks on space shuttle Atlantis' aft, or back, section continue on Launch Pad 39A at NASA's Kennedy Space Center today. Technicians also will install several cameras in the shuttle's payload bay.

Workers finished attaching the orbiter midbody umbilical unit from the pad's rotating service structure to the shuttle, and then leak checks were conducted and completed.

Atlantis' cargo, consisting of Express Logistics Carrier 1 and 2, holding about 28,000 pounds of supplies and spare parts for the International Space Station, were moved from the pad's changeout room into the shuttle's payload bay yesterday.

Meanwhile, at NASA's Johnson Space Center in Houston, the six STS-129 astronauts are participating in a final prelaunch meeting with the Mission Control Center's flight director team today, and they’ll also be reviewing final flight data.

Enceladus' Icy Surface

Cassini captured this raw image on its Nov. 02, 2009, flyby of Enceladus. The camera was pointing toward Enceladus from approximately 10,000 kilometers (6,000 miles) away.

This image has not been validated or calibrated. A validated/calibrated image will be archived with the NASA Planetary Data System in 2010.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

Image Credit: NASA/JPL/Space Science Institute

Spring Bloom in New Zealand Waters

Off the east coast of New Zealand, cold rivers of water that have branched off from the Antarctic Circumpolar Current flow north past the South Island and converge with warmer waters flowing south past the North Island. The surface waters of this meeting place are New Zealand's most biologically productive. This image of the area on October 25, 2009, from the MODIS sensor on NASA’s Aqua satellite shows the basis for that productivity: large blooms of plantlike organisms called phytoplankton.

Phytoplankton use chlorophyll and other pigments to absorb sunlight for photosynthesis, and when they grow in large numbers, they change the way the ocean surface reflects sunlight. Caught up in eddies and currents, the blooms create intricate patterns of blues and greens that spread across thousands of square kilometers of the sea surface.

Especially bright blue areas may indicate the presence of phytoplankton called coccolithophores, which are coated with calcium-carbonate (chalk) scales that are very reflective. The duller greenish-brown areas of the bloom may be diatoms, which have a silica-based covering.

In addition to their importance as the foundation of the ocean food web, phytoplankton play a key role in the climate because, like plants on land, they absorb carbon dioxide from the atmosphere. When they die, they sink to the ocean floor where the carbon they took from the atmosphere is stored for thousands of years.

X-38 Crew Return Vehicle Finds New Home

One of NASA's three X-38 Crew Return Vehicle technology demonstrators that flew at NASA's Dryden Flight Research Center at Edwards Air Force Base, Calif., a decade ago has found a new home in America's heartland.

In this image from test flights in 1999, the X-38 research vehicle drops away from NASA's B-52 mothership immediately after being released from the B-52's wing pylon. More than 30 years earlier, this same B-52 launched the original lifting-body vehicles flight tested by NASA and the Air Force at what is now called the Dryden Flight Research Center and the Air Force Flight Test Center.

The wingless lifting body craft was transferred this past weekend from NASA's Johnson Space Center in Houston to the Strategic Air and Space Museum, located just off Interstate 80 at Ashland, Neb., about 20 miles southeast of Omaha. The X-38 adds to the museum's growing collection of aerospace vehicles and other historical artifacts.

The move of the second X-38 built to the museum has a fitting connection, as the X-38 vehicles were air-launched from NASA's famous B-52B 008 mothership. The B-52 bomber served as the backbone of the Air Force's Strategic Air Command during the command's history.

Prior to cancellation, the X-38 program was developing the technology for proposed vehicles that could return up to seven International Space Station crewmembers to Earth in case of an emergency. These vehicles would have been carried to the space station in the cargo bay of a space shuttle and attached to station docking ports. If an emergency arose that forced the ISS crew to leave the space station, a Crew Return Vehicle would have undocked and returned them to Earth much like the space shuttle, although the vehicle would have deployed a parafoil for the final descent and landing.

space shuttle Atlantis' payload bay

Launch Pad 39A technicians at NASA's Kennedy Space Center in Florida will install the cargo for the STS-129 mission into space shuttle Atlantis' payload bay today. The payload consists of Express Logistics Carrier 1 and 2, holding about 28,000 pounds of supplies and spare parts for the International Space Station.

Workers also will attach the orbiter midbody umbilical unit from the pad's rotating service structure to the shuttle today. The unit provides access to and permits servicing of Atlantis' mid-fuselage area. Liquid oxygen and liquid hydrogen for the fuel cells and gases, such as nitrogen and helium, are provided through the unit.

The six Atlantis astronauts returned to NASA's Johnson Space Center in Houston yesterday after completing the Terminal Countdown Demonstration Test, or TCDT,

training. They'll conduct final launch preparations at Johnson before flying back to Kennedy for the anticipated launch to the space station at 2:28 p.m. EST on Nov. 16.

On Launch Pad 39A at NASA's Kennedy Space Center in Florida, the STS-129 crew, appear ready for liftoff following the completion of their Terminal Countdown

Demonstration Test

Atlantis and Crew Prepare for Flight The STS-129 mission will be commanded by Charles O. Hobaugh and piloted by Barry E. Wilmore. Mission Specialists are Robert L. Satcher Jr., Mike Foreman, Randy

Bresnik and Leland Melvin. Wilmore, Satcher and Bresnik will be making their first trips to space. Atlantis and its crew will deliver two control moment gyroscopes, equipment and EXPRESS Logistics Carrier 1 and 2 to the International Space Station. The mission will

feature three spacewalks.

Atlantis also will return station crew member Nicole Stott to Earth and is slated to be the final space shuttle crew rotation flight.

Cruising to the Moon

How long does it take humans to travel to the moon? Currently, Constellation is planning for the trans-lunar coast to take no longer than 4 days, or 96 hours. Apollo’s design requirement was for the coast time to range between 60 hours and 100 hours. The actual missions (Apollo 10-17) varied from 72 hours to 83 hours.

So why would it take longer on the future missions? It may not actually. At this point, Constellation is in the requirements definition and preliminary design phase for the lunar exploration portion of the program therefore requirements are set for the most stressing - maximum and minimum - types of conditions.

The trans-lunar cruise duration is a function of the energy or change in velocity (delta-V) applied at the trans-lunar injection, or TLI, burn. The energy requirements for the TLI burn will vary depending on where the planned landing site is located on the moon and when the mission is launched, among other factors. So, if a mission is launched on a more favorable opportunity, less energy will be required for the TLI burn and the trip would be quicker.

Since Constellation is planning for worst-case conditions at this point, the transfer time in the current plan minimizes the amount of propellant, and therefore the mass, required for trans-lunar injection. When Constellation flies actual missions to the moon, there will likely be the same flexibility as Apollo to shorten the duration of the flight toward the moon if it is desirable to do so.

pirit Embedded in Soft Soil on Mars as Engineers Devise Methods to 'Free Spirit'

This view from the panoramic camera on NASA's Mars Exploration Rover Spirit shows the terrain surrounding the location called "Troy," where Spirit became embedded in soft soil during the spring of 2009. The hundreds of images combined into this view were taken beginning on the 1,906th Martian day (or sol) of Spirit's mission on Mars (May 14, 2009) and ending on Sol 1943 (June 20, 2009).

Near the center of the image, in the distance, lies Husband Hill, where Spirit recorded views from the summit in 2005. For scale, the parallel tracks are about 1 meter (39 inches) apart. The track on the right is more evident because Spirit was driving backwards, dragging its right-front wheel, which no longer rotates.

The bright soil in the center foreground is soft material in which Spirit became embedded after the wheels on that side cut through a darker top layer. The composition of different layers in the soil at the site became the subject of intense investigation by tools on Spirit's robotic arm.

In recent weeks, Engineers have been using test rovers on Earth to prepare for extracting the sand-trapped Spirit rover. While amnesia-like symptoms in recent days might delay the start of planned drives by Spirit geared towards extricating it, the Mars Exploration Rover team remains hopeful. "If they are intermittent and infrequent, they are a nuisance that would set us back a day or two when they occur. If the condition becomes persistent or frequent, we will need to go to an alternate strategy that avoids depending on flash memory, " said Project Manager John Callas of NASA's Jet Propulsion Laboratory. In these amnesia events, Spirit fails to record data from the day's activities onto the type of computer memory -- non-volatile "flash" memory -- that can retain the data when the rover powers down for its energy-conserving periods of "sleep."

Spirit has worked on Mars for more than 69 months in what was originally planned as a three-month mission.

Flying Low Over Pine Island Glacier

From: Michael Studinger, Lamont-Doherty Earth Observatory, co-principal investigator, gravimeter team

PUNTA ARENAS, Chile – After flying for several hours over a windswept Southern Ocean on Tuesday, Oct. 27, the mission director announces that we will be slowly descending towards Antarctica's Pine Island Glacier. Just below are the Hudson Mountains, a small group of extinct volcanoes poking through the ice.

As we approach our survey area, John Sonntag with NASA’s Wallops Flight Facility and I watch the navigation display and admire the pilots' precision as they steer the giant NASA DC-8 aircraft to the start of our first survey line.

We are here to measure the glacier's ice surface with lasers, its bottom with radar, and estimate the depth of the water below it with an instrument that measures the gravity pull from above the glacier.

All systems are functioning well and we are excited about the data coming in. The computer screen mounted on the University of Kansas' radar rack is a popular in-flight gathering spot since it provides a real-time view of the radar data that allows us to “see” the bottom of the glacier while we fly over it.

The structures we see are quite amazing and we toss around ideas about what this tells us about how the glacier is responding to warming temperatures. Science can be so much fun! After criss-crossing Pine Island Glacier several times, it’s time to head home to Punta Arenas.

A heavily crevassed area of Pine Island Glacier. Shows you how very difficult it would be to travel and work on the surface of this glacier. Data are best collected from aircraft flying over the glacier or from space.

The calving front of Pine Island Glacier. This is the end of the glacier where pieces of ice break apart from the floating glacier and become icebergs.

Flying at low elevation over the edge of the floating part of Pine Island Glacier. Winds have blown away the sea ice resulting in an area with open water called a polynya. The goal of this flight is to estimate the thickness of the water layer beneath the floating ice shelf from gravity data.

The Hudson Mountains near the edge of Pine Island Glacier are a small group of extinct volcanoes that poke through the ice and make for spectacular scenery.

Interactions with Aerosols Boost Warming Potential of Some Gases

For decades, climate scientists have worked to identify and measure key substances -- notably greenhouse gases and aerosol particles -- that affect Earth’s climate. And they’ve been aided by ever more sophisticated computer models that make estimating the relative impact of each type of pollutant more reliable.

Yet the complexity of nature -- and the models used to quantify it -- continues to serve up surprises. The most recent? Certain gases that cause warming are so closely linked with the production of aerosols that the emissions of one type of pollutant can indirectly affect the quantity of the other. And for two key gases that cause warming, these so-called “gas-aerosol interactions” can amplify their impact.

“We’ve known for years that methane and carbon monoxide have a warming effect,” said Drew Shindell, a climate scientist at the NASA Goddard Institute for Space Studies (GISS) in New York and lead author of a study published this week in Science. “But our new findings suggest these gases have a significantly more powerful warming impact than previously thought.”

Mixing a Chemical Soup

When vehicles, factories, landfills, and livestock emit methane and carbon monoxide into the atmosphere, they are doing more than just increasing their atmospheric concentrations. The release of these gases also have indirect effects on a variety of other atmospheric constituents, including reducing the production of particles called aerosols that can influence both the climate and the air quality. These two gases, as well as others, are part of a complicated cascade of chemical reactions that features competition with aerosols for highly reactive molecules that cleanse the air of pollutants.

Aerosols can have either a warming or cooling effect, depending on their composition, but the two aerosol types that Shindell modeled -- sulfates and nitrates -- scatter incoming light and affect clouds in ways that cool Earth. They are also related to the formation of acid rain and can cause respiratory distress and other health problems for those who breathe them.

Human activity is a major source of sulfate aerosols, but smokestacks don’t emit sulfate particles directly. Rather, coal power production and other industrial processes release sulfur dioxide -- the same gas that billows from volcanoes -- that later reacts with atmospheric molecules called hydroxyl radicals to produce sulfates as a byproduct. Hydroxyl is so reactive scientists consider it an atmospheric "detergent" or "scrubber" because it cleanses the atmosphere of many types of pollution.

In the chemical soup of the lower atmosphere, however, sulfur dioxide isn’t the only substance interacting with hydroxyl. Similar reactions influence the creation of nitrate aerosols. And hydroxyls drive long chains of reactions involving other common gases, including ozone.

Methane and carbon monoxide use up hydroxyl that would otherwise produce sulfate, thereby reducing the concentration of sulfate aerosols. It's a seemingly minor change, but it makes a difference to the climate. “More methane means less hydroxyl, less sulfate, and more warming,” Shindell explained.

His team’s modeling experiment, one of the first to rigorously quantify the impact of gas-aerosol interactions on both climate and air quality, showed that increases in global methane emissions have caused a 26 percent decrease in hydroxyl and an 11 percent decrease in the number concentration of sulfate particles. Reducing sulfate unmasks methane’s warming by 20 to 40 percent over current estimates, but also helps reduce negative health effects from sulfate aerosols.

In comparison, the model calculated that global carbon monoxide emissions have caused a 13 percent reduction in hydroxyl and 9 percent reduction in sulfate aerosols.

Nitrogen oxides -- pollutants produced largely by power plants, trucks, and cars -- led to overall cooling when their effects on aerosol particles are included, said Nadine Unger, another coauthor on the paper and a climate scientist at GISS. That’s noteworthy because nitrogen oxides have primarily been associated with ozone formation and warming in the past.

A New Approach

To determine the climate impact of particular greenhouse gases, scientists have traditionally relied on surface stations and satellites to measure the concentration of each gas in the air. Then, they have extrapolated such measurements to arrive at a global estimate.

The drawback to that "abundance-based approach," explained Gavin Schmidt, another GISS climate scientist and coauthor of the study, is that it doesn’t account for the constant interactions that occur between various atmospheric constituents. Nor is it easy to parse out whether pollutants have human or natural origins.

“You get a much more accurate picture of how human emissions are impacting the climate -- and how policy makers might effectively counteract climate change -- if you look at what’s emitted at the surface rather than what ends up in the atmosphere,” said Shindell, who used this “emissions-based” approach as the groundwork for this modeling project.

However, the abundance-based approach serves as the foundation of key international climate treaties, such as the Kyoto Protocol or the carbon dioxide cap-and-trade plans being discussed among policymakers. Such treaties underestimate the contributions of methane and carbon monoxide to global warming, Shindell said.

Unpacking the Implications

According to Shindell, the new findings underscore the importance of devising multi-pronged strategies to address climate change rather than focusing exclusively on carbon dioxide. “Our calculations suggest that all the non-carbon dioxide greenhouse gases together have a net impact that rivals the warming caused by carbon dioxide."

In particular, the study reinforces the idea that proposals to reduce methane may be an easier place for policy makers to start climate change agreements. “Since we already know how to capture methane from animals, landfills, and sewage treatment plants at fairly low cost, targeting methane makes sense,” said Michael MacCracken, chief scientist for the Climate Institute in Washington, D.C.

This research also provides regulators insight into how certain pollution mitigation strategies might simultaneously affect climate and air quality. Reductions of carbon monoxide, for example, would have positive effects for both climate and the public’s health, while reducing nitrogen oxide could have a positive impact on health but a negative impact on the climate.

“The bottom line is that the chemistry of the atmosphere can get hideously complicated,” said Schmidt. “Sorting out what affects climate and what affects air quality isn’t simple, but we’re making progress.”

New Celestial Map Gives Directions for GPS

Many of us have been rescued from unfamiliar territory by directions from a Global Positioning System (GPS) navigator. GPS satellites send signals to a receiver in your GPS navigator, which calculates your position based on the location of the satellites and your distance from them. The distance is determined by how long it took the signals from various satellites to reach your receiver.

The system works well, and millions rely on it every day, but what tells the GPS satellites where they are in the first place?

"For GPS to work, the orbital position, or ephemeris, of the satellites has to be known very precisely," said Dr. Chopo Ma of NASA's Goddard Space Flight Center in Greenbelt, Md. "In order to know where the satellites are, you have to know the orientation of the Earth very precisely."

This is not as obvious as simply looking at the Earth – space is not conveniently marked with lines to determine our planet's position. Even worse, "everything is always moving," says Ma. Earth wobbles as it rotates due to the gravitational pull (tides) from the moon and the sun. Even apparently minor things like shifts in air and ocean currents and motions in Earth's molten core all influence our planet's orientation.

Just as you can use landmarks to find your place in a strange city, astronomers use landmarks in space to position the Earth. Stars seem the obvious candidate, and they were used throughout history to navigate on Earth. "However, for the extremely precise measurements needed for things like GPS, stars won't work, because they are moving too," says Ma.

What is needed are objects so remote that their motion is not detectable. Only a couple classes of objects fit the bill, because they also need to be bright enough to be seen over incredible distances. Things like quasars, which are typically brighter than a billion suns, can be used. Many scientists believe these objects are powered by giant black holes feeding on nearby gas. Gas trapped in the black hole's powerful gravity is compressed and heated to millions of degrees, giving off intense light and/or radio energy.

Most quasars lurk in the outer reaches of the cosmos, over a billion light years away, and are therefore distant enough to appear stationary to us. For comparison, a light year, the distance light travels in a year, is almost six trillion miles. Our entire galaxy, consisting of hundreds of billions of stars, is about 100,000 light years across.

A collection of remote quasars, whose positions in the sky are precisely known, forms a map of celestial landmarks in which to orient the Earth. The first such map, called the International Celestial Reference Frame (ICRF), was completed in 1995. It was made over four years using painstaking analysis of observations on the positions of about 600 objects.


a led a three-year effort to update and improve the precision of the ICRF map by scientists affiliated with the International Very Long Baseline Interferometry Service for Geodesy and Astrometry (IVS) and the International Astronomical Union (IAU). Called ICRF2, it uses observations of approximately 3,000 quasars. It was officially recognized as the fundamental reference system for astronomy by the IAU in August, 2009.

Making such a map is not easy. Despite the brilliance of quasars, their extreme distance makes them too faint to be located accurately with a conventional telescope that uses optical light (the light that we can see). Instead, a special network of radio telescopes is used, called a Very Long Baseline Interferometer (VLBI).

The larger the telescope, the better its ability to see fine detail, called spatial resolution. A VLBI network coordinates its observations to get the resolving power of a telescope as large as the network. VLBI networks have spanned continents and even entire hemispheres of the globe, giving the resolving power of a telescope thousands of miles in diameter. For ICRF2, the analysis of the VLBI observations reduced uncertainties in position to angles as small as 40 microarcseconds, about the thickness of a 0.7 millimeter mechanical pencil lead in Los Angeles when viewed from Washington. This minimum uncertainty is about five times better than the ICRF, according to Ma.


These networks are arranged on a yearly basis as individual radio telescope stations commit time to make coordinated observations. Managing all these coordinated observations is a major effort by the IVS, according to Ma.

Additionally, the exquisite precision of VLBI networks makes them sensitive to many kinds of disturbances, called noise. Differences in atmospheric pressure and humidity caused by weather systems, flexing of the Earth's crust due to tides, and shifting of antenna locations from plate tectonics and earthquakes all affect VLBI measurements. "A significant challenge was modeling all these disturbances in computers to take them into account and reduce the noise, or uncertainty, in our position observations," said Ma.

Another major source of noise is related to changes in the structure of the quasars themselves, which can be seen because of the extraordinary resolution of the VLBI networks, according to Ma.

The ICRF maps are not only useful for navigation on Earth; they also help us find our way in space -- the ICRF grid and some of the objects themselves are used to assist spacecraft navigation for interplanetary missions, according to Ma.

Despite its usefulness for things like GPS, the primary application for the ICRF maps is astronomy. Researchers use the ICRF maps as driving directions for telescopes. Objects are referenced with coordinates derived from the ICRF so that astronomers know where to find them in the sky.

Also, the optical light visible to our eyes is only a small part of the electromagnetic radiation produced by celestial objects, which ranges from less-energetic, low-frequency radiation, like radio and microwaves, through optical light to highly energetic, high-frequency radiation like X-rays and gamma-rays.

Astronomers use special detectors to make images of objects producing radiation our eyes can't see. Even so, since things in space can have extremely different temperatures, objects that generate radiation in one frequency band, say optical, do not necessarily produce radiation in another, perhaps radio. The main scientific use of the ICRF maps is a precise grid for combining observations of objects taken using different frequencies and accurately locating them relative to each other in the sky.

Astronomers also use the frame as a backdrop to record the motion of celestial objects closer to us. Tracing how stars and other objects move provides clues to their origin and evolution.

The next update to the ICRF may be done in space. The European Space Agency plans to launch a satellite called Gaia in 2012 that will observe about a half-million quasars. Gaia uses an optical telescope, but because it is above the atmosphere, the satellite will be able to clearly see these faint objects and precisely locate them in the sky. The mission will use quasars that are optically bright, many of which are too dim in radio to be useful for the VLBI networks. The project expects to have enough observations by 2018 to 2020 to produce the next-generation ICRF.

ICRF2 involved researchers from Australia, Austria, China, France, Germany, Italy, Russia, Ukraine, and the United States; and was funded by organizations from these countries, including NASA. The analysis efforts are coordinated by the IVS. The IAU officially adopts the ICRF maps and recommends their occasional updates.

Bill Steigerwald
NASA Goddard Space Flight Center