Russian Cargo Craft Undocks From Station

An unpiloted Russian Progress cargo spacecraft undocked from the International Space Station Monday, completing its second and final undocking from the station since arriving in late November 2013.
The ISS Progress 53 resupply craft undocked from the aft port of the Zvezda service module at 9:29 a.m. EDT as the station orbited over Mongolia. 
From a window in the Russian segment of the station, Expedition 40 Flight Engineer Alexander Skvortsov photographed the departing Progress cargo ship as it began a 15-second separation burn to move a safe distance away from the orbiting complex.
A 3-minute, 16-second deorbit burn beginning at 12:34 p.m. slowed the Progress for its destructive re-entry in the Earth’s atmosphere over the Pacific Ocean less than an hour later. Progress resupply ships are not designed to be recovered, so, like its predecessors, Progress 53 was refilled with trash and station discards after its original cargo was unloaded by the station crew.
Progress 53 delivered 2.9 tons of food, fuel and supplies when it first arrived at the station on Nov. 29, following a flight that included a “fly-by” of the station two days earlier to test revamped Kurs automated rendezvous system hardware.  Because of a technical glitch unrelated to the new Kurs system, the Nov. 29 approach and docking of the Progress was controlled manually by the station’s crew using TORU, the Telerobotically Operated Rendezvous Unit.
To complete the testing of the Kurs-NA rendezvous hardware and its associated software, Progress 53 undocked from Zvezda on April 23 and successfully performed an automated docking to that port two days later. The enhanced Kurs system will be incorporated into future Progress vehicles to reduce weight by eliminating several navigational antennas, thus enabling the Progress to carry additional supplies to the station.
The final departure of Progress 53 clears the Zvezda docking port for the arrival in August of the European Space Agency’s fifth Automated Transfer Vehicle, ATV-5. Named for the Belgian physicist and astronomer Georges Lemaitre, the ATV-5 is scheduled for launch from Kourou, French Guiana, on an Ariane 5 rocket in late July.
In addition to monitoring the departure of Progress 53, the station’s six-person Expedition 40 crew supported a variety of experiments that can be conducted only in a microgravity environment and continued preparations for next week’s spacewalk.
Skvortsov and Flight Engineer Oleg Artemyev began the day with an assessment of their arm muscles before moving on to a review of the tasks they will conduct during their spacewalk slated for June 19. Later, they gathered the tools and equipment they will use during the excursion. The two spacewalkers will mount a new integrated command and telemetry system on Zvezda and replace a payload rack on the Russian segment with a payload boom previously installed in a temporary location.
 Artemyev also checked out Otklik experiment hardware for monitoring particle impacts on the station. He rounded out his day by downloading data for the Identification study, which measures the loads on the station during dynamic events such as Monday’s Progress undocking.
Station Commander Steve Swanson began the day drawing a blood sample from Flight Engineer Alexander Gerst. The astronauts themselves are the experiment for human physiology studies aboard the station as their blood, saliva and urine samples are processed and stored in freezers for further analysis back on Earth. As NASA works toward sending humans on longer voyages beyond low Earth orbit, it is critical to understand how the human body adapts and changes during long-duration spaceflight.
Afterward, Swanson installed a new test sample for the Japan Aerospace Exploration Agency’s Resist Tubule experiment, which takes a look at the mechanisms for gravity resistance in plants. Results from this study will help researchers learn more about the evolution of plants and enable efficient plant production both on Earth and in space. For future deep space missions, plants may be able to provide astronauts with regenerative sources of food and supplemental methods of converting carbon dioxide into oxygen.

Flight Engineer Reid Wiseman spent the morning gathering U.S. spacewalking tools and equipment to loan to his Russian crewmates for next week’s spacewalk. The equipment list included tethers and a pair of helmet cameras that can provide live, first-person views from the spacewalk.
Gerst meanwhile participated in a periodic fitness evaluation while working on an exercise bike known as the Cycle Ergometer with Vibration Isolation and Stabilization System, or CEVIS. Wiseman assisted Gerst with blood pressure measurements for part of the evaluation.
 Following a break for lunch, Swanson led Wiseman and Gerst through some handover activities to help them become familiar with the systems and payloads of the U.S. segment of the station. Wiseman and Gerst arrived aboard the station on May 28 along with Flight Engineer Max Suraev. The three new crew members also had time set aside on their own throughout the day to learn the ropes of their orbital home.
Suraev otherwise spent most of his workday removing a series of brackets in the Rassvet Mini-Research Module-1.
Wiseman later swapped out a manifold bottle in the Combustion Integrated Rack. This facility, which includes an optics bench, combustion chamber, fuel and oxidizer control and five different cameras, allows a variety of combustion experiments to be performed safely aboard the station. Experiments performed in this facility could lead to improvements in spacecraft materials selection and strategies for putting out accidental fires aboard spacecraft.
Afterward, Wiseman joined Swanson in the Destiny lab to talk with CBS Evening News’ Scott Pelley. The two astronauts discussed their participation in social media and the scientific research aboard the station.

New Station Trio Set for Wednesday Launch

While the orbiting Expedition 40 crew supported botanical research and robotics Tuesday aboard the International Space Station, the three crewmates who will return the station to its full six-person crew on Wednesday are in the final stages of preparations for launch.
NASA astronaut Reid Wiseman, cosmonaut Maxim Suraev of the Russian Federal Space Agency and European Space Agency astronaut Alexander Gerst are set to launch aboard their Soyuz TMA-13M spacecraft from the Baikonur Cosmodrome in Kazakhstan at 3:57 p.m. EDT Wednesday (1:57 a.m. Thursday, Kazakh time). Less than six hours later, at 9:48 p.m., Soyuz Commander Suraev will dock the Russian spacecraft to the Rassvet module on the Earth-facing side of the station.
 Commander Steve Swanson and Flight Engineers Oleg Artemyev and Alexander Skvortsov, who have been aboard the complex since March 27, will welcome the new flight engineers aboard when the hatches open at 11:25 p.m.
NASA Television coverage of the launch begins at 3 p.m. Wednesday. Live coverage resumes at 9 p.m. for the docking, followed by hatch opening coverage at 11 p.m.
 The Soyuz that will carry Wiseman, Suraev and Gerst to the station was rolled out by train from the integration building on Monday and erected on the launch pad.
 Meanwhile aboard the orbiting complex, Swanson spent much of Tuesday morning in the station’s Kibo laboratory breaking down equipment used for the most recent session of the Resist Tubule experiment. This Japan Aerospace Exploration Agency study takes a look at the mechanisms for gravity resistance in plants. Results from this study will help researchers learn more about the evolution of plants and enable efficient plant production both on Earth and in space. During a long-duration mission beyond low Earth orbit, plants can provide future astronauts with regenerative sources of food and supplemental methods of converting carbon dioxide into oxygen.
Afterward, Swanson used the Kibo module’s airlock to transfer a replacement camera to the exterior of the station. The robotic teams at the Mobile Servicing System Operations Complex in Saint Hubert, Quebec, and the Mission Control Center in Houston worked together to command the Special Purpose Dexterous Manipulator, or Dextre, to retrieve the camera from the airlock and install it near the elbow joint of the Canadarm2 robotic arm. As part of an operation that began last week with the transfer of a camera into the system’s mobile base, which together with Dextre and Canadarm2 forms the Mobile Servicing System, Dextre has become the first robot to repair itself in space.
 Swanson took a break from his work to talk with CBS correspondents Bill Harwood and Peter King and ABC News anchor Dan Kloeffler.
On the Russian side of the complex, Skvortsov and Artemyev teamed up for the Russian BAR experiment, which is studying methods of detecting a leak from one of the station’s modules.
Skvortsov and Artemyev later participated in examinations of the veins in their legs as teams on the ground keep track of any changes to the cosmonaut’s health during the six-month stay aboard the station.
Artemyev also updated software for the Napor-mini RSA experiment, which utilizes an optical telescope and a small radar system for monitoring Earth’s environment.

Scientists Seek Answers With Space Station Thyroid Cancer Study

The multi-national efforts that go into research aboard the International Space Station show that working together can yield results with universal benefits. This is especially the case when talking about human health concerns such as cancer. Researchers make use of the microgravity environment aboard the space station to seek answers to questions about the nature of cancer cells. With the Microgravity on Human Thyroid Carcinoma Cells (Cellbox-Thyroid) study, recently conducted in orbit, the hope is to reveal answers that will help in the fight against thyroid cancer.
The American Cancer Society estimates about 62,980 cases of thyroid cancer in the U.S. for 2014. The thyroid is a gland in the neck that secretes hormones that help the body to regulate growth and development, metabolism, and body temperature. The Cellbox-Thyroid study is enabled through a collaborative effort between NanoRacks, Airbus Defense and Space, the German Aerospace Center (DLR) and the Center for the Advancement of Science in Space (CASIS) to facilitate the microgravity investigation aboard the space station.
“NanoRacks is hosting this German research study aboard the U.S. National Laboratory,” said Jeff Manber, CEO of NanoRacks. “It may well make critical advances in understanding and even delaying the onset of cancer in the thyroid.”
The overall aim of the Cellbox-Thyroid study is to identify new biomarkers and target proteins for use in developing new cancer-fighting drugs. The investigation has roots in research performed in SIMBOX aboard the Sino-German Chinese Shenzhou-8 mission. During that 2011 study, Daniela-Gabriele Grimm, M.D., principal investigator and researcher with the Department of Biomedicine, Pharmacology at Aarhus University in Aarhus, Denmark, looked at cancer cells in microgravity and found that tumors behave less aggressively in that environment. Grimm’s published findings appeared earlier this year in the Federation of the American Societies for Experimental Biology Journal.
“A further important finding was that a tumor grows three-dimensionally in space. The mechanism for this finding will also be investigated in this Cellbox-Thyroid experiment,” said Grimm. This result published in Elsevier Biomaterials 2013.
With the Cellbox-Thyroid study, Grimm seeks to build on her earlier conclusions by identifying the proteins that can be targeted to anti-cancer therapies. Insights into what controls how tumors grow may lead to knowledge for enhancing treatments on Earth. The experiments took place aboard the space station soon after berthing of the SpaceX Dragon on April 20. The samples returned to Earth aboard the same vehicle on May 18 for further analysis by researchers on the ground.
Specifically, researchers are looking for the microgravity environment to reveal an altered gene expression pattern—how the gene’s encoded information directs protein molecule assembly. They also seek to learn about the proteins expressed or secreted by the cells, called proteome and secretome. Isolating how the cell processes work could lead to new thyroid cancer drugs and provide a better understanding of the mechanism leading to cancer development for new strategies in thyroid cancer therapy.
“Spaceflight experiments are of great value for cell biology research in general and for cancer research in particular,” said Grimm. “Our experiments indicate that microgravity induce[s] changes in the expression and secretion of genes and proteins involved in cancer cell proliferation, metastasis, and survival, shifting the cells toward a less aggressive phenotype.”
In microgravity, researchers anticipate the cancer cells will form three-dimensional multicellular tumor spheroids. This behavior was identified in the previous study, where cells floated without mixing with each other in the microgravity environment. This finding revealed that biochemical components on the cell surfaces were responsible for the initial cell-to-cell interactions required for spheroid formation.
For the Cellbox-Thyroid study, researchers used six experiment containers that fit into the NanoRacks platform and centrifuge for the test runs. After the experiments completed, the samples were stored for return to Earth. Once back on the ground, researchers will analyze the samples and compare them to data from ground controls using simulated microgravity via a random positioning machine and the results from the SIMBOX study.
The hope is that the continuance of this research from the original SIMBOX mission to the space station study will confirm findings and build the statistical data. Grimm plans an additional follow up study, called Spheroids, for 2015. Spheroids will operate for two weeks while in orbit, providing data that—together with its predecessors—may one day take a chunk out of those annual thyroid cancer statistics.

Botanical Studies, Dragon Departure Preps for Station Crew

The three-person Expedition 40 crew spent its first full workday Thursday aboard the International Space Station working with a trio of botanical experiments and preparing for Sunday’s departure of the SpaceX Dragon cargo craft.
Following the crew’s daily planning conference with the flight control teams around the world, Commander Steve Swanson set up a test sample for the Japan Aerospace Exploration Agency’s Resist Tubule experiment, which takes a look at the mechanisms for gravity resistance in plants.  Results from this study will help researchers learn more about the evolution of plants and enable efficient plant production both on Earth and in space. During a long-duration mission beyond low-Earth orbit, plants can provide future astronauts with regenerative sources of food and supplemental methods of converting carbon dioxide into oxygen.
 Afterward, Swanson teamed up with Flight Engineer Oleg Artemyev to transfer research samples from some of the freezers aboard the station into the GLACIER freezer that will be returning to Earth aboard the SpaceX Dragon cargo craft.
On Sunday, Dragon is set to be detached from the Earth-facing side of the station's Harmony module and unberthed through commands sent by robotic ground controllers at mission control in Houston operating the Canadarm 2 robotic arm. Dragon then will be maneuvered into place for its release, which is scheduled for 9:26 a.m. EDT. Dragon, which delivered about 2.5 tons of science and supplies to the station for the SpaceX-3 commercial resupply services mission when it arrived at the complex April 20, will be carrying 3,500 pounds of NASA science samples and cargo when it splashes down for recovery off the coast of California at 3:02 p.m. (12:02 p.m. PDT).
 Swanson later thinned out “Outredgeous” red romaine lettuce seedlings growing in the Veggie plant facility to give the remaining plants more room to grow.  Veggie is a low-cost plant growth chamber that uses a flat-panel light bank that includes red, blue and green LEDs for plant growth and crew observation. For the Veg-01 experiment, researchers are testing and validating the Veggie hardware, and the plants will be harvested and returned to Earth to determine food safety.
 The commander then transferred the Micro-7 BioCell habitat to the Commercial Generic Bioprocessing Apparatus.  Micro-7 takes a look at how microgravity affects the genetic expression and physical shape of non-dividing cells, which are the majority of cells that make up the human body.

After checking out a crew command control panel for Sunday’s Dragon activities, Swanson fielded questions from Denver television station KMGH-TV for an in-flight interview in the station’s Destiny laboratory. Swanson, who hails from Steamboat Springs, Colorado, discussed life aboard the station and his attempts to spot his hometown from space.
Swanson rounded out his day by removing the Biotube-MICRO payload from one of the station’s EXPRESS racks for return aboard Dragon. This experiment investigates the potential for magnetic fields to orient plant roots as they grow in microgravity. Plants are not directly sensitive to magnetic fields, but starch grains, called amyloplasts, in plant cells respond to external magnetic fields. Results from Biotube-MICRO may lead to using high-strength magnetic fields in space as a substitute for gravitational cues for growing plants during long-duration missions.
 On the Russian side of the complex, Artemyev conducted the Uragan Earth-observation experiment, which seeks to document and predict the development of natural and man-made disasters on Earth. He also participated in the Interactions experiment, which studies the impacts of personal, cultural and national differences among crew members.
 Flight Engineer Alexander Skvortsov focused much of his attention on routing and connecting cables for the European Space Agency’s Automated Transfer Vehicle (ATV) control panel and proximity communication equipment inside the Zvezda service module.   The fifth and final ATV cargo ship, dubbed “Georges Lemaître,” is targeted to launch to the station this summer.
Meanwhile, the three flight engineers who will return the station to its full six-person crew complement are now in the homestretch leading up to their May 28 launch to the station. Reid Wiseman of NASA, Max Suraev of Roscosmos and Alexander Gerst of the European Space Agency wrapped up pre-flight activities Thursday in Star City, Russia, and flew to the Baikonur Cosmodrome in Kazakhstan where their Soyuz TMA-13M spacecraft is being prepared for launch.

NASA Mars Rover Curiosity Wrapping Up Waypoint Work

Portions of powdered rock collected by drilling into a sandstone target last week have been delivered to laboratory instruments inside NASA's Curiosity Mars rover, and the rover will soon drive on toward its long-term destination on a mountain slope.
Other instruments on the rover have inspected the rock's interior exposed in the hole and in drill cuttings heaped around the hole. The target rock, "Windjana," is a sandstone slab within a science waypoint area called "The Kimberley."
The camera and spectrometer at the end of Curiosity's robotic arm examined the texture and composition of the cuttings.  The instrument that fires a laser from atop the rover's mast zapped a series of points inside the hole with sharpshooter accuracy.
The rover team has decided not to drill any other rock target at this waypoint. In coming days, Curiosity will resume driving toward Mount Sharp, the layered mountain at the middle of Mars' Gale Crater. The rover is carrying with it some of the powdered sample material from Windjana that can be delivered for additional internal laboratory analysis during pauses in the drive.
The mission's two previous rock-drilling sites, at mudstone targets, yielded evidence last year of an ancient lakebed environment with key chemical elements and a chemical energy source that long ago provided conditions favorable for microbial life.
NASA's Mars Science Laboratory Project is using Curiosity to assess ancient habitable environments and major changes in Martian environmental conditions. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, built the rover and manages the project for NASA's Science Mission Directorate in Washington.

Expedition 39 Trio Set to Depart Station

Three Expedition 39 crew members are wrapping up more than six months aboard the International Space Station as they get set for the journey back to Earth aboard a Soyuz spacecraft Tuesday.
Expedition 39 Commander Koichi Wakata of the Japan Aerospace Exploration Agency, Flight Engineer Rick Mastracchio of NASA and Soyuz Commander Mikhail Tyurin of Roscosmos, the Russian Federal Space Agency, will bid farewell to their station crewmates and close the hatches to their Soyuz TMA-11M spacecraft docked to the Rassvet module Tuesday afternoon. NASA Television coverage of the farewells and hatch closure begins at 3 p.m. EDT.
 When their Soyuz undocks at 6:36 p.m., it will mark the end of Expedition 39 and the start of Expedition 40 under the command of NASA astronaut Steve Swanson. Wakata, the first Japanese commander of the orbiting complex, passed the helm of the station over to Swanson during a change of command ceremony Monday afternoon.
 A deorbit burn at 9:04 p.m. will put the Soyuz on track for a parachute-assisted landing in the steppe of Kazakhstan southeast of Dzhezkazgan at 9:58 p.m. (7:58 a.m. Wednesday, Kazakh time). The landing will complete a journey of over 79 million statute miles and more than 3,000 orbits of the Earth for the trio since launching to the station from the Baikonur Cosmodrome in Kazakhstan back on Nov. 7.

Live NASA Television coverage of the undocking begins at 6:15 p.m. Coverage resumes at 8:45 p.m. for the deorbit burn and continues through the landing and post-landing activities.
Swanson and his crewmates, Alexander Skvortsov and Oleg Artemyev of Roscosmos, will operate the station as a three-person crew for two weeks until the arrival of three new crew members -- Reid Wiseman of NASA, Max Suraev of Roscosmos and Alexander Gerst of the European Space Agency. The trio of new flight engineers, who are wrapping up pre-flight activities in Star City, Russia, will fly to Baikonur on Thursday to begin the homestretch of preparations for their May 28 launch to the station.
Samples from the ongoing microbiome investigation will return on the Soyuz TMA-11M. The microbiome study looks at the impact of space travel on the immune system and on human microbiomes – microbes living in and on the human body at any given time. Samples from crew members’ bodies and the space station environment are taken periodically to monitor changes in the immune system and microbiomes. The results of this study may add to research on health impacts to people who live and work in extreme environments on Earth, and help with research on early disease detection, metabolic function and immune system deficiency.

How Does Your Garden Glow? NASA's OCO-2 Seeks Answer

Science is full of serendipity -- moments when discoveries happen by chance or accident while researchers are looking for something else. For example, penicillin was identified when a blue-green mold grew on a Petri dish that had been left open by mistake.
Now, satellite instruments have given climate researchers at NASA and other research institutions an unexpected global view from space of a nearly invisible fluorescent glow that sheds new light on the productivity of vegetation on land. Previously, global views of this glow from chlorophyll were only possible over Earth’s ocean, using NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on NASA’s Terra and Aqua spacecraft.
When the Japanese Greenhouse gases Observing SATellite (GOSAT), known as “IBUKI” in Japan, launched into orbit in 2009, its primary mission was to measure levels of carbon dioxide and methane, two major heat-trapping greenhouse gases in Earth’s atmosphere. However, NASA researchers, in collaboration with Japanese and other international colleagues, found another treasure hidden in the data: fluorescence from chlorophyll contained within plants. Although scientists have measured fluorescence in laboratory settings and ground-based field experiments for decades, these new satellite data now provide the ability to monitor what is known as solar-induced chlorophyll fluorescence on a global scale, opening up a world of potential new applications for studying vegetation on land.
A “signature” of photosynthesis, solar-induced chlorophyll fluorescence is an indicator of the process by which plants convert light from the sun into chemical energy. As chlorophyll molecules absorb incoming radiation, some of the light is dissipated as heat, and some radiation is re-emitted at longer wavelengths as fluorescence.
Enter NASA’s Orbiting Carbon Observatory-2 (OCO-2). Researchers who study the interaction of plants, carbon and climate are eagerly awaiting fluorescence data from the OCO-2 satellite mission, scheduled to launch in July 2014. The instrument aboard OCO-2 will make precise measurements of carbon dioxide in the atmosphere, recording 24 observations a second versus GOSAT’s single observation every four seconds, resulting in almost 100 times more observations of both carbon dioxide and fluorescence than GOSAT.
“Data from OCO-2 will extend the GOSAT time series and allow us to observe large-scale changes to photosynthesis in a new way,” said David Schimel, lead scientist for the Carbon and Ecosystems research program at NASA’s Jet Propulsion Laboratory, Pasadena, Calif., which manages the OCO-2 mission for NASA. “The fluorescence data may turn out to be a unique and very complementary data set of the OCO-2 mission.”
“OCO-2’s fluorescence data, when combined with the observatory’s atmospheric carbon dioxide measurements, will increase the value of the OCO-2 mission to NASA, the United States and world,” said Ralph Basilio, OCO-2 project manager at JPL.
Turning the Sun Off
Being able to see fluorescence from space allows scientists to estimate photosynthesis rates over vast scales, gleaning insights into vital processes that affect humans and other living things on Earth. “The rate of photosynthesis is critical because it’s the process that drives the absorption of carbon from the atmosphere and agricultural [food] production,” said Joseph Berry, a researcher in the Department of Global Ecology at Carnegie Institution for Science in Stanford, Calif.
Measuring the fluorescent “glow” may sound simple, but the tiny signal is overpowered by reflected sunlight. “Imagine that you’re in your child’s bedroom and they have a bunch of glow-in-the-dark stars on the ceiling," Schimel said. "Then you turn the lights on. The stars are still glowing, but looking for that glow with the lights on is like looking for fluorescence amidst the reflected sunlight.” Retrieving the fluorescence data requires disentangling sunlight that is reflected by plants from the light given off by them -- in other words, figuring out a way to “turn the sun off.”
Researchers found that by tuning GOSAT’s spectrometer (an instrument that can measure different parts of the spectrum of light) to look at very narrow channels, they could see parts of the spectrum where there was fluorescence but less reflected solar radiation. “It’s as if you had put on a pair of glasses that filtered out the radiation in your child’s room except for that glow from the stars,” said Schimel.
Scientists are excited about the new measurement because it will give them better insight into how Earth's plants are taking up carbon dioxide. According to the Global Carbon Project, a non-governmental organization devoted to developing a complete picture of the carbon cycle, our burning of fossil fuels on Earth had produced nearly 35 billion tons of carbon dioxide by 2011. This is almost 5 tons of carbon dioxide for every one of Earth’s seven billion inhabitants.
About half of that carbon dioxide remains in the atmosphere. The other half is dissolved in the ocean or taken up by Earth’s biosphere (living organisms on land and in the ocean), where it is tucked away in carbon reservoirs or “sinks.” These sinks are shielding us from the full effect of our emissions.
Plants in a High-Carbon World
“Everybody that’s using fossil fuels right now is being subsidized by the biosphere,” said Berry. “But one of the key unknowns is -- what’s going to be happening in the long term? Is it going to continue to subsidize us?”
The future of Earth’s plants depends largely on one of the carbon cycle’s key ingredients: water. Plants need water to carry out photosynthesis. When their water supply runs low, such as during times of drought, photosynthesis slows down.
For the past quarter century, satellite instruments such as MODIS and the Advanced Very High Resolution Radiometer (AVHRR) on NOAA polar-orbiting satellites have enabled researchers to monitor plant health and productivity by measuring the amount of “greenness,” which shows how much leaf material is exposed to sunlight. The drawback of using the greenness index, however, is that greenness doesn’t immediately respond to stresses -- water stress for example -- that reduce photosynthesis and productivity.
“Plants can be green, but not active,” said JPL research scientist Christian Frankenberg, also a member of the OCO-2 science team. “Imagine an evergreen needle-leaf forest at high elevation in winter. The trees are still green, but they’re not photosynthesizing.”
Solar-induced fluorescence data would tell you straight away that something had happened, explains Schimel, but greenness doesn’t tell you until the plants are already drooping and maybe dead.
About 30 percent of the photosynthesis that occurs in Earth’s land regions takes place in the tropical rainforest of the Amazon, which encompasses about 2.7 million square miles (7 million square kilometers) of South America. The Amazon is home to more than half of Earth’s terrestrial biomass and tropical forest area -- making it one of the two most important land regions for carbon storage (the other being the Arctic, where carbon is stored in the soil).
Recent studies in the Amazon using fluorescence measurements have examined how photosynthesis rates change during wet and dry seasons. Most of the results show that during the dry season, photosynthesis slows down. According to Berry, when the air is dry and hot, it makes sense for plants to conserve water by closing their stomates (pores). “During the dry season when it would cost the plants a lot of water, photosynthesis is dialed down and the forest becomes less active,” he said.
In 2005 and 2010, the Amazon basin experienced the type of droughts that historically have happened only once in a century. Greenness measurements indicated widespread die-off of trees and major changes to the forest canopy (treetops) after the droughts, but fluorescence data from GOSAT exposed even milder water stress in the dry season of normal years. “There is the potential that as climate change proceeds, these droughts will become more severe. The areas that support tropical rainforest could decrease,” said Berry. Less tropical forest means less carbon absorbed from the air.
In addition, as trees decay, they release carbon dioxide back into the atmosphere, creating a scenario whereby the biosphere potentially becomes a source of carbon rather than a sink. “If there is a dieback of the tropical rainforest, that might add to the effect of fossil fuel carbon dioxide on climate change,” said Frankenberg.
Because photosynthesis is one of the key processes involved in the carbon cycle, and because the carbon cycle plays an important role in climate, better fluorescence information could help resolve some uncertainties about the uptake of carbon dioxide by plants in climate models. “We think fluorescence is going to help carbon cycle models get the right answer,” said Berry. “If you don’t have the models right, how can you get the rest of it right?”
“We really don’t understand the quantitative relationship between climate and photosynthesis very well, because we’ve only been able to study it at very small scales,” said Schimel. “Measuring plant fluorescence from space may be an important addition to the set of techniques available to us.”