NASA OCO-2 Satellite Takes First Look at Earth's Carbon Dioxide

Artist's rendition of NASA's OCO-2 satellite in orbit. 

OCO-2 was launched on July 2, 2014 and made its first science measurements a month later, on Aug. 6. 

Credit: JPL/NASA

NASA's newest satellite has arrived in its final orbit and begun tracking levels of the heat-trapping gas carbon dioxide in Earth's atmosphere.

The Orbiting Carbon Observatory 2 (OCO-2), which blasted off July 2, arrived in its final orbit 438 miles (705 kilometers) above the Earth on Aug. 3.

The satellite then collected its first test data three days later while flying over Papua New Guinea, agency officials said.

"The initial data from OCO-2 appear exactly as expected, the spectral lines are well resolved, sharp and deep," OCO-2's chief architect and calibration lead, Randy Pollock, of NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement Monday (Aug. 11).

"We still have a lot of work to do to go from having a working instrument to having a well-calibrated and scientifically useful instrument, but this was an important milestone on this journey."



OCO-2 is the first operational NASA satellite dedicated to measuring atmospheric levels of carbon dioxide, which scientists say is largely responsible for Earth's recent warming trend.

Concentrations of the gas in Earth's air have risen from 280 parts per million (ppm) before the Industrial Revolution to about 400 ppm today, primarily due to the burning of fossil fuels and other human activities.

OCO-2 will use its single scientific instrument, a grading spectrometer, to gather precise CO2 data thousands of times each day, helping researchers get a much clearer picture of how the gas is cycling through the atmosphere, what sources are pumping it out, and which "sinks" are sucking it up, NASA officials said.

OCO-2 will become the leader of the Afternoon Constellation, or A-Train, as shown in this artist's concept. 

Japan’s Global Change Observation Mission - Water (GCOM-W1) satellite and NASA’s Aqua, CALIPSO, CloudSat and Aura satellites follow. 

Image Credit: NASA

By reaching its ultimate, near-polar orbit, OCO-2 joined five other Earth-observation satellites in a constellation known as the "A-Train." (The name is short for "Afternoon Train"; all of the spacecraft cross the equator going north in the early afternoon local time.)

The OCO-2 mission team will calibrate the spacecraft's spectrometer over the next few weeks.

The satellite will also beam to Earth up to 1 million scientific measurements every day, to help test out data-processing systems on the ground, NASA officials said.

The $465 million mission should start delivering calibrated science data before the end of 2014, they added.

Using antineutrinos to monitor nuclear reactors

Dr. Nils Haag developed an experimental setup that allowed him to determine the missing spectrum of uranium 238. 

Credit: Wenzel Schuermann / TU München 

When monitoring nuclear reactors, the International Atomic Energy Agency (IAEA) has to rely on input given by the operators. 

In the future, antineutrino detectors may provide an additional option for monitoring.

However, heretofore the cumulative antineutrino spectrum of uranium 238 fission products was missing.

Physicists at Technische Universität München have now closed this gap using fast neutrons from the Heinz Maier Leibnitz Neutron Research Facility.

In addition to neutrons, the fission reaction of nuclear fuels like plutonium or uranium releases antineutrinos.

These are also electrically neutral, but can pass matter very easily, which is why they can be discerned only in huge detectors.

Recently, however, detectors on the scale of only one cubic meter have been developed. They can measure antineutrinos from a reactor core, which has generated great interest at the IAEA.

Prototypes of these detectors already exist and collect data at distances of around 10 meters from a reactor core.

Changes in the composition of nuclear fuels in the reactor e.g., when weapons-grade U-239 is removed, can be determined by analyzing the energy and rate of antineutrinos.

This would free the IAEA from having to rely on representations of reactor operators.

Antineutrino spectrum of uranium 238 revealed
In the 1980s the antineutrino spectra of three main fuel isotopes, uranium 235, plutonium 239 and plutonium 241, were determined.

However, the antineutrino spectrum of the fourth main nuclear fuel, uranium 238, which accounts for approximately 10 percent of the total antineutrino flux, remained unclear.

It had only been estimated using inaccurate theoretical calculations and thus limited the accuracy of the antineutrino predictions.

Dr. Nils Haag

Dr. Nils Haag from the Chair of Experimental Astroparticle Physics at TU München recently developed an experimental setup at the FRM II that allowed him to determine the missing spectrum of uranium 238.

"I needed a high flux of fast neutrons to induce the fission of the U-238," says the physicist. This is why he located his experimental setup at the NECTAR radiography and tomography station of the FRM II, a source of fast neutrons.

Second detector allows background-free measurement
The neutrons induce nuclear fission in a film of U-238. The radioactive decay products then emit electrons and antineutrinos.

The electrons were investigated using a scintillator – a block of plastics that converts the kinetic energy of the electrons into light. A photomultiplier then translates this into electrical signals.

The nuclear decay also generates gamma radiation that produces unwanted events in the scintillator.

Therefore, Haag placed a second detector right in front of the scintillator: a so-called multi-wire proportional chamber.

Since only charged particles like electrons trigger a signal in the gas detector, the researcher was able to determine and subtract the proportion of gamma radiation.

Haag then inferred the antineutrino spectrum using this background-free measurement data.

Method allows better monitoring of reactor cores
The measurement of the antineutrino spectrum can be used to monitor the status, performance and even composition of reactor cores.

"Our results open the door to predict with significantly higher accuracy the expected antineutrino spectrum emitted by a reactor running on a fuel composition reported by the operator," explains Dr. Nils Haag.

"Deviations of antineutrino detector measurement data from expected reactor signals can thus be exposed."

The development of this methodology is embedded in basic research on the phenomenon of so-called "sterile" antineutrinos.

Comparing previously made measurements and predictions of reactor antineutrino spectra gave rise to the assumption that some of the antineutrinos turned "sterile" after being produced.

They were then no longer able to react with other matter. A better understanding of this effect would expand our knowledge of elementary physical processes.

More information: 
Experimental Determination of the Antineutrino Spectrum of the Fission Products of U238, N. Haag, A. Gütlein, M. Hofmann, L. Oberauer, W. Potzel, K. Schreckenbach, and F. M. Wagner, Phys. Rev. Lett. 112, 122501 (2014), DOI: 10.1103/PhysRevLett.112.122501

Scottish scientists use Backpacks to monitor personal air pollution

Scientists in Edinburgh are using hi-tech backpacks to study personal exposure to air pollution.

Air pollution is routinely measured by a network of urban monitors at fixed locations across Scotland.

But these are unable to provide a detailed picture of an individual's exposure throughout the day.

Scientists at the Centre for Ecology & Hydrology have provided volunteers with backpacks fitted with particle monitors and GPS satellite tracking technology.

Graph on laptop, showing David’s exposure to air pollution in Edinburgh

The volunteers wear the small backpacks throughout the day and sleep with them beside their beds at night.

The results are then analysed to assess exposure to tiny particles, mainly from combustion, known as particulate matter.

Doctors say there is a strong link between exposure to particulate matter and the risk of heart attack.

Dave Newby

Professor Dave Newby, of the University of Edinburgh and the British Heart Foundation, said: "We all think that when we breathe in air pollution, it must provoke pneumonia, or asthma or lung problems. But actually, it kills far more people from heart disease.

"What we've found is that the biggest trigger is the particulate matter that we breathe in. In the urban environment, the biggest contributor to that is diesel engines."

Dr Stefan Reis

The research investigating personal exposure to air pollution is being led by Dr Stefan Reis.

He believes the development of mobile air pollution monitoring equipment will be cheaper and more effective than investing in a larger network of fixed monitoring stations to cover whole cities.

He told reporters: "It's always easy to call for more monitoring but what we are trying to achieve is getting smarter monitoring.

"We're not trying to cover the whole countryside or city with many, very accurate monitors, which are very expensive, but using the combination of personal sensors, monitors on buses or trams, together with existing networks to get a much better picture of the actual exposure of people in the city."

The Scottish government has rejected criticism from environmentalists, who say ministers are failing in their duty to reduce air pollution levels.

Paul Wheelhouse

Environment minister Paul Wheelhouse said: "Working in partnership with local authorities, we've developed a network of monitoring sites, there's over 90 of them in Scotland, and we're using those to develop our strategy at a local level.

"In some cases, where they fail to meet the Scottish standard, which is a tough standard, they identify an air quality management area and that then triggers between the Scottish government and the local authority, who have a duty to deliver good air quality locally, to tackle that."

Roadside air pollution monitoring station

But Green MSP Patrick Harvie argues air pollution levels will remain too high until there is a fundamental change in transport policy in Scotland.

He said: "This locked-in pattern that we have to high transport demand is expensive, it's inefficient, it's unhealthy and it contributes to local and global pollution.

"Unless we see change in transport policy, we are not going to see change to the pollution levels in our cities and we'll be here in another 10 years listening to another environment minister saying much the same thing."

Japan to launch satellites to monitor oceans against piracy and encroachment

The Senkaku islands, known as Diaoyu by aggressive China.

Japan plans to launch Earth Observation (EO) satellites to monitor the world's oceans as the aggressive Chinese government ships sailed into waters around islands controlled by Tokyo.

The Japanese Cabinet office plans to launch nine EO satellites in the next five years to counter piracy and monitor the movements of foreign ships intruding into Japanese territorial waters.

They will also collect data for forecasting natural disasters such as tsunamis and tropical storms.

The report, which cabinet officials could not immediately confirm, came as Japan's coastguard said three Chinese government ships entered waters around the Senkaku islands in the East China Sea.

The maritime surveillance vessels entered the 12-nautical-mile zone around Uotsurijima, one of the Senkaku islands which oppressive China calls the Diaoyus, at about 9:30 am (0030 GMT), the Japanese coastguard reported.

The ships left the area shortly before 1:00 pm, according to an update by the coastguard.

Ships from the two countries have for months traded warnings over intrusions into what each regard as their territory, as Beijing and Tokyo jostle over political claims of ownership of the islands.

The territorial row that dates back four decades reignited last September when Tokyo nationalised three islands in the chain, in what it said was a mere administrative change of ownership.

Former Japanese prime minister Yukio Hatoyama came under fire in June after he said he understood China's aggressive claim to the islands.