spacer
Spacer Spacer Spacer Spacer Spacer Spacer Spacer Spacer Spacer Spacer Spacer Spacer Spacer
 
 
Science@Ames
 
Space ScienceSpace Science @ Ames features research in infrared astrophysics, laboratory astrophysics, extrasolar planets, planetary sciences, exobiology, and astrobiology.
 
 
Earth ScienceEarth Science @ Ames features basic and applied research in atmospheric and biospheric sciences, and conducts airborne science campaigns.
 
 
Biological ScienceBioSciences @ Ames features research in fundamental space biology, and provides engineering and payload development for the International Space Station.
 

 
Features
 
LADEE Project Scientist Update: December 2014
December 17, 2013
 

LADEE Star Tracker Image with Craters Lichtenberg A and Schiaparelli E The image shown here was acquired on Feb. 8, 2014, around 23:45 UTC, while LADEE was carrying out atmospheric measurements. A series of five images were taken at one-minute intervals, and caught features in the northern western hemisphere of the moon. LADEE was traveling approximately 60 miles (100 km) per minute along its orbit. All images were taken during lunar night, but with Earthshine illuminating the surface. This final image views craters Lichtenberg A and Schiaparelli E in the smooth mare basalt plains of Western Oceanus Procellarum, west of the Aristarchus plateau.

It's been about a year since LADEE started its Science Mission Phase on Nov. 21, 2013, and successfully completed it on March 1, 2014. LADEE then went on to acquire low altitude data for another month and a half, before impacting the lunar surface as planned on April 18, 2014. With the science data acquisition completed, the science team worked hard over spring and summer to ready the instrument measurements and background information for submission to the Planetary Data System (PDS). The instrument teams finished off this task in September, 2014, a year after launch. Now planetary scientists everywhere can delve into the LADEE exosphere and dust datasets!

The LADEE science team also has been busy analyzing the returned data, figuring out how the exosphere breathes and changes, and how the moon's tenuous dust shroud varies in time and space.

The Lunar Dust Experiment (LDEX) discovered a low-density cloud of small dust particles over the part of the moon that faces the more-or-less steady rain of micrometeoroid particles onto the lunar surface. The Earth/moon system orbits the sun with an average speed of 30 km/sec (67,000 mph), and like bugs on a car windshield, the interplanetary micrometeoroid materials smack into the "upstream" side of the Earth and moon. On Earth these cause meteors, which burn up in the atmosphere, but with the almost negligible atmosphere on the moon, these particles smash into the surface with tremendous speed. Each particle impact sends a spray of ejecta up into the lunar sky; this process is continuous but really increases when the moon encounters a micrometeoroid stream. The flux of incoming particles can increase by factors of up to ten times the normal rates - we see these as meteor showers on Earth. On the moon, it's a very heavy rain of tiny, tiny rocks, and the spray of ejecta increases accordingly.

LADEE saw these meteor shower dust particles several times during the mission. LADEE also looked for mysterious "levitated" dust, thought to be suspended by electric forces over the sunrise and sunset terminators. This mystery was prompted in part by astronaut sightings of a horizon glow seen from orbit. However, the spacecraft's instruments found no evidence of anything that could be seen by the human eye.

However, LADEE's Ultraviolet/Visible Spectrometer (UVS) has detected a very weak glow in the anti-sunward direction, possibly due to a population of very small grains of lunar ejecta. Picture the moon as an extremely weak comet, throwing off this very tenuous cloud of tiny particles into a kind of tail stretching out behind, away from the sun.

We have learned that the major gas species in the thin lunar atmosphere are three noble gases: helium, neon and argon. LADEE's neutral mass spectrometer (NMS) systematically measured these species, and we now know that helium and neon are supplied by the solar wind. The flux of doubly-ionized solar wind helium went up and down from day to day (as measured by LADEE's lunar companions, the two ARTEMIS spacecraft), and the NMS helium measurements tracked those changes. In fact, for helium it's easy come, easy go! The dayside lunar surface gets very hot, over 240 degrees Fahrenheit (117 degrees Celsius) at the equator near noon, and the helium atoms pick up this heat as they bounce across the surface. Some helium atoms move so fast as a result that they escape the moon completely and are lost. On daily time scales, the supply of helium provided by the solar wind is balanced by the loss of the escaping portion of helium. But when the moon's phase is full, it is located inside a protected region, the Earth's geomagnetic tail, where it is shielded from the solar wind. Here, the supply of solar wind helium is cut off. But the hot lunar dayside surface continues to drive the escape of some of the resident helium. Because of this ongoing loss process, and a temporary cutoff in supply, we see the density decrease with time. When the moon re-emerges into the solar wind, the supply is restored and the exosphere quickly recovers to equilibrium.

Neon, delivered by the solar wind in very small quantities, generally cannot escape like helium does. It's too heavy and doesn't travel fast enough to leave the moon. And once there, like an unwelcome house guest, it sticks around. And sticks around. In fact, about the only way the neon leaves is when the sun's ultraviolet radiation causes photoionization: the neon atom loses an electron, and the resulting positively charged ion is swept away by the solar wind. But photoionization of neon takes a long time - over 200 days. So even though neon is a very minor solar wind constituent, the slow loss rate means it can build up to levels comparable to helium in the moon's atmosphere.

The third lunar noble gas is argon, specifically, argon-40. This isotope comes from the decay of naturally occurring radioactive potassium-40, found in the rocks of all the terrestrial planets as a leftover from formation. As potassium-40 in the moon decays, the argon-40 product is able to diffuse and percolate up to the lunar surface, where it becomes part of the tenuous atmosphere. Lunar argon behaves differently from helium and neon; it condenses on the moon's cold nightside where temperatures drop below -280 degrees Fahrenheit (-173 Celsius). As the moon slowly rotates, and the condensed argon sees sunrise, temperatures rise and the atoms jump off the surface into the exosphere again. Some of these jumping argon atoms leap back into the cold nightside, and are re-trapped on the cold surface until sunrise occurs for that patch of real estate. But the moon's argon exhibits other interesting behavior. LADEE discovered that argon-40 creates a local bulge above an unusual part of the moon's surface, the region containing Mare Imbrium and Oceanus Procellarum. This happens to be the place where potassium-40 is most abundant on the surface, and there may be a connection between the atmospheric argon, the surface potassium and deep interior sources.

UVS also monitored the two minor species sodium and potassium over the course of LADEE's mission. These observations show that sodium follows a monthly cycle, responding to passages through the geomagnetic tail. This suggests that the solar wind is one influence on releasing sodium from the surface into the exosphere, possibly through a process called "sputtering." Sputtering occurs when a solar wind protons slam into lunar surface materials and deposit their energy there. The energy deposition process can knock other atoms, including sodium, out of these materials. UVS also found that exospheric sodium increases in density in response to meteoroid showers, possibly because these micrometeoroids are vaporizing lunar regolith grains. Sodium is one of the easiest species to liberate. Potassium exhibits a monthly variation as well, though slightly different from that of sodium. Other metal species may also be showing up in UVS data. Several external stimuli can affect the thin lunar atmosphere, among them solar wind sputtering, desorption by extreme ultraviolet photons, and micrometeoroid impact vaporization. It can be challenging to untangle cause and effect!

LADEE's science team is working to share this and more fascinating in-depth research results with the public and the scientific community. Several LADEE presentations will be given at the Fall Meeting of the American Geophysical Union this week in San Francisco, including: new studies by the LDEX team on the micrometeoroid streams that increase the dust exosphere; NMS identification of water and carbon dioxide in the lunar atmosphere; a study of how rocket exhaust from Chang'e 3's landing and LADEE's own maneuvers interacts with the lunar surface; a model simulation of how the sodium exosphere varies over a lunar month. Look for more presentations and papers in the coming months!

Rick Elphic
NASA's Ames Research Center, Moffett Field, Calif.
http://www.nasa.gov/mission_pages/ladee/main/index.html


Image credit: NASA Ames

 
Workshop on the Potential for Finding Life in a Europa Plume
December 15, 2013
 

Artist's conception of water vapor plume erupting from the icy surface of Europa, a moon of Jupiter, based on data from the Hubble Space Telescope.

SAVE THE DATE: Wednesday, February 18, 2015


The NASA Astrobiology Institute (NAI) and the Solar System Exploration Research Virtual Institute (SSERVI) will co-host the Workshop on the Potential for Finding Life in a Europa Plume at NASA Ames Research Center, Moffett Field, California.

Current Europa missions under study by NASA are focused on answering the question "Is Europa habitable?" However, the potential presence of water plumes on the satellite could present an opportunity to pursue the question "Is there life on Europa?" Answering this question is far more challenging because measurements currently possible may provide only ambiguous results from a mission that either orbits or flies by Europa at relatively high velocity. To that end, NASA's Planetary Science Division is convening a workshop to consider strategies to investigate Europa's putative plumes for evidence of life.

A second announcement with further details and abstract submission instructions will be forthcoming by early January 2015. Although participation in person is encouraged, provision will be made for remote participation. The workshop will be followed on Feb. 19-20 by a meeting of the Outer Planets Assessment Group that will also be held at the Ames Research Center.


Julie Fletcher
astrobiology.nasa.gov

Images: NASA/ESA/K. Retherford/SWRI


 
2014 NASA Honor Awards Ceremony
December 15, 2013
 

November 19, 2014 NASA Honor Awards ceremony was held at Ames Research Center


Biosphere Science Branch, Code SGE


Exceptional Engineering Achievement Medal

Donald Sullivan, Biosphere Science Branch, Code SGE



Flight Systems Implementation Branch, Code SCF


Equal Employment Opportunity Medal

Dana Bolles, Flight Systems Implementation Branch, Code SCF




Outstanding Leadership Medal

Paresh A. Bhavsar, Flight Systems Implementation Branch, Code SCF




Atmospheric Science Branch, Code SGG


Exceptional Achievement Medal

Kent C. Shiffer, Atmospheric Science Branch, Code SGG




Space Science And Astrobiology Division, Code SS


Exceptional Service Medal

Caroline To, Space Science And Astrobiology Division, Code SS




Astrophysics Branch, Code SSA


Exceptional Scientific Achievement Medal

Daniel Huber, Astrophysics Branch, Code SSA




Exobiology Branch, Code SSX


Exceptional Service Medal

David Des Marals, Exobiology Branch, Code SSX




Visit Ames Imaging Library System for highligts of the Honor Awards Ceremony.


Images: NASA Ames


 
Lights, Camera, Artificial Gravity! The Premiere of NASA's Fruit Fly Lab
December 12, 2013
 

The fruit fly-Drosophila melanogaster-is helping researchers understand how spaceflight affects the immune system's response to infection.


The most advanced system to date for studying fruit flies in space, NASA's Fruit Fly Lab, is making its debut aboard the International Space Station. The Fruit Fly Lab-01 mission, planned to launch to the station in December aboard SpaceX's fifth commercial resupply services (CRS) mission, is the first of a series of fruit fly investigations NASA plans to conduct.

The fruit fly-a widely studied biological research model-plays a lead role in this study and will help us better understand how spaceflight impairs the body's ability to fight infections. Model organisms, such as fruit flies, are simpler and easier to research than humans. Their study can shed light on the mechanisms of human health and disease because we share the basic biochemical machinery of life. Fruit flies can fill in for humans in this research because the insect's immune system closely resembles human innate immunity-our first line of defense against infections.

Lights built into the system will create an Earth-like day/night cycle for the flies and cameras record high-definition video of fly behavior, which can indicate their health. Artificial gravity, generated by the NanoRacks Astrium centrifuge, will allow researchers to distinguish the effects of weightlessness from other aspects of spaceflight, such as radiation and launch forces. The centrifuge can simulate the levels of gravity found on Earth, the moon and Mars.

This investigation follows on the heels of other spaceflight fruit fly studies. However, none of the previous hardware systems had the combined capabilities of artificial gravity, day/night lighting, video observation, tissue preservation and the ability to separate multiple generations of flies. The system's new tools for in-flight preservation of fruit fly tissue can be used for studies of gene expression, such as those that will be performed by NASA's GeneLab.

Fruit Fly Lab can support longer-duration studies in space than were previously possible. Multiple generations of space-reared fruit flies can be bred continuously with sufficient hardware and food.

"At the end of the 28-day validation mission we expect to be studying the children, grandchildren and possibly great-grandchildren of the original population of fruit flies that are launching aboard SpaceX CRS-5," said Sharmila Bhattacharya, director of the Biomodel Performance and Behavioral Laboratory at NASA's Ames Research Center in Moffett Field, California, and project scientist for the mission.

An immune response study will be conducted during the mission, major goals of which are to show that the system operates smoothly aboard the station and delivers high-quality data.

"Data from this validation study will confirm and extend findings from shorter-duration studies we conducted aboard the space shuttle that examined how spaceflight impacts fruit fly immune responses," said Bhattacharya. "We are conducting a host-pathogen study involving immune challenge in orbit where both the flies and the bacteria are under the influence of spaceflight,"

During spaceflight microbes can become more infectious and the immune systems of complex organisms such as humans and fruit flies can weaken. Bhattacharya's team at Ames is studying the underlying biological mechanisms responsible for this diminished immune response in the host organism. Such knowledge can be applied to protecting human health, including the health of astronauts who will someday travel deeper into space than ever before, such as on a journey to Mars.

Groups of flies will be transported to the space station in habitats known as fly cassettes. Half of the flies will be weightless during the study and half will be exposed to simulated Earth gravity. The crew will periodically feed the flies and preserve samples of fruit fly tissues for analysis by Bhattacharya's team. Some of the flies' food will contain a microbe that will infect the insects. The researchers will compare the ability of fruit flies to resist infection by the food-borne microbe between the flies that were weightless, those exposed to simulated Earth's gravity in space and flies that remained on Earth.

Once the Fruit Fly Lab-01 study completes, the Fruit Fly Lab research platform will be made available for proposed spaceflight research from the scientific community. NASA anticipates a series of yearly sequels to follow the debut mission.


Gianine M. Figliozzi
Space Biosciences Division
NASA's Ames Research Center


Image Credit: NASA / Dominic Hart


 
NASA's IceBridge Antarctic Campaign Wraps Up
December 9, 2014
 

NASA's Operation IceBridge recently completed its 2014 Antarctic campaign, marking the mission's sixth set of flights over Antarctica.


NASA's Operation IceBridge recently completed its 2014 Antarctic campaign, marking the mission's sixth set of flights over Antarctica. During the six-week-long deployment from Punta Arenas, Chile, researchers aboard NASA's DC-8 airborne laboratory measured land and sea ice from above to continue building a record of change in the Antarctic.

The campaign began on Oct. 16, with a flight aimed at measuring sea ice in the Weddell Sea. This first flight - like many that followed - was a repeat mission, covering areas that IceBridge studied in previous campaigns. The repeat flights this year were of particular importance because it has been two years since IceBridge was last in Punta Arenas.

Repeating lines flown in previous years is crucial for understanding how ice conditions are changing over time. In addition, some survey lines follow the paths measured by NASA's Ice, Cloud and Land Elevation Satellite, or ICESat, from 2003 to 2009. This helps cover the gap between ICESat and its successor, ICESat-2, scheduled to launch in a few years.

In addition to these repeated surveys, IceBridge carried out new missions intended to expand coverage into new areas. One example would be the Nov. 14 flight that measured farther inland from previous surveys of the Foundation Ice Stream and Support Force Glacier. The ice surface, bedrock and sub-ice water depth data collected on this flight will be helpful for scientists projecting future changes to the Antarctic Ice Sheet.

Two other newly designed missions also had the aim of setting a baseline for validating ICESat-2 measurements. On Oct. 23 and 26, the DC-8 flew a survey around the South Pole at 88 degrees south. Every planned ICESat-2 orbit intersects at 88 degrees, giving scientists a reference point for verifying the satellite's accuracy.

One of these pole flights was part of a set of eight surveys considered the highest priority by IceBridge mission planners. These flights, known as baseline missions, target areas that are rapidly changing and thus needing repeat measurement, or are otherwise scientifically important, like flights building comparison points for ICESat-2. Of the 22 flights IceBridge carried out during this campaign, seven were in this baseline category. In addition to the South Pole flight, three targeted glaciers in West Antarctica and the Antarctic Peninsula, and three collected data on Antarctic sea ice.

On top of the mission's scientific work, IceBridge also hosted high-profile visitors and reached out to students both in the United States and Chile. On the Oct. 28 flight, IceBridge was joined by NASA's Chief Scientist Ellen Stofan and Michael Hammer, the U.S. Ambassador to Chile.

As in previous campaigns, IceBridge researchers reached out to students both back in the United States and in Chile. On several survey flights students used an online text chat portal that allowed them to ask researchers questions over the DC-8's satellite communication system. During these chats, IceBridge communicated with 867 students in 37 classrooms.

With the conclusion of several weeks in the field, IceBridge's various instrument teams now look ahead to processing the data they collected and to preparing for IceBridge's upcoming Arctic campaign, scheduled to begin in March 2015.

For more information about NASA's IceBridge mission, visit:
www.nasa.gov/Icebridge


George Hale
Earth Science @ Ames
NASA's Goddard Space Flight Center, Greenbelt, Maryland


Image Credit: NASA / George Hale


+ View Archives