STP-H5-Fabry Perot Spectrometer for Methane (STP-H5 FPS) - 12.13.17

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
Methane is a powerful greenhouse gas with many human-caused and natural sources, and understanding where it arises on Earth improves climate change models. The STP-H5-Fabry Perot Spectrometer for Methane (STP-H5 FPS) investigation demonstrates a new atmospheric methane sensor that is smaller, cheaper and simpler than current sensors. Results improve designs for future space-based methane observatories that can focus on high latitudes, where methane production from thawing permafrost is a serious concern.
Science Results for Everyone
Information Pending

The following content was provided by William Heaps, and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
William Heaps, Johns Hopkins Applied Physics Lab, Laurel, MD, United States

Information Pending

NASA Goddard Space Flight Center, Greenbelt, MD, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
Technology Demonstration Office (TDO)

Research Benefits
Scientific Discovery, Earth Benefits

ISS Expedition Duration
September 2016 - February 2018

Expeditions Assigned

Previous Missions
Information Pending

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Experiment Description

Research Overview

  • Methane is an important greenhouse gas that has been increasing in the atmosphere over the last few decades. The reasons for these changes is not well understood.
  • The measurements obtained by the STP-H5-Fabry Perot Spectrometer for Methane (STP-H5 FPS) instrument permit mapping of methane at a fine scale to help determine the sources and sinks of atmospheric methane.
  • Methane transport models enable some mapping to extend to higher latitudes beyond the orbit of the space station.
  • These measurements serve to improve modeling of global warming and our understanding of processes contributing to global warming.
  • This instrument also serve as a step on the path to new, small, targeted spectroscopic instruments enabling an improved understanding of our global environment at an affordable cost.


Atmospheric methane (CH4) is the second leading manmade contribution to global warming by greenhouse gases, amounting to nearly one third of that from carbon dioxide (CO2). The global background abundance of CH4, and its gross source and sink, is relatively well known from ground-based measurements in remote regions , and the centennial increase in CH4 from about 0.7 ppmv preindustrial to 1.8 ppmv currently is well-documented . The global sink of CH4 occurs largely in chemical reaction with OH molecules with little trend over the last few decades . What is not well known, however, is the partitioning among different CH4 source processes, their regional distribution, and the attribution of temporal changes to underlying process forcing.
Natural sources of CH4 account for about one-third of the emission total, dominated by wetland emissions in the tropics and sub-Arctic boreal regions, with additional contributions from termites, ocean biology, and a geological source of unknown significance. The wetland source is particularly variable, linked to temperature, precipitation, and surface hydrological changes .
CH4 emissions resulting from human activities are the largest global source globally with major components from coal mining, oil and gas extraction, ruminant and rice agriculture, landfills, and biomass burning. Each of these processes has its unique spatial distribution, and sector emission uncertainties from bottom-up and top-down inventories are estimated to be on the order of 20% . A major challenge here is to understand the current global trend in CH4, which is generally attributed to manmade source variations, but with unknown sector and natural contributions The reasons for the observed changes in growth rate and the implications for future changes in atmospheric CH4 are not understood .
The uncertainty in our knowledge of CH4 regional sector source magnitudes, processes, and variations basically derives from the inherent difficulty of measuring CH4 in the atmosphere with sufficiently high precision across the wide range of spatial scales required for a trace gas with highly local sources and an approximate 9-year lifetime. The basic message from limited observations to date is that CH4 gradients driven by surface emissions, atmospheric (plus small surface) losses, and transport are distinct, global, and highly variable.
The overall goal of The Space Test Program-H5-Fabry Perot Spectrometer (STP-H5 FPS) investigation is to develop, construct, and operate an innovative space instrument to measure CH4. The measurements will complement missions planned by NASA and other nations targeted at global greenhouse gases. The data are used to address key science questions related to the distribution, fluxes, and trends of CH4 that will improve our basic process understanding and enable better projections of greenhouse gas climate impacts in the future.
The top-level science questions are:
1) What is the current global baseline distribution of CH4 in the atmosphere?
2) What is the balance of the principal CH4 sources and sinks?
3) What processes have driven observed changes in CH4 growth rate over the last 20 years and how may they influence future growth rates as climate changes?
4) What complement of space-based remote sensing instruments is needed to monitor greenhouse gases.
The Fabry-Perot based spectrometer is well suited to address these questions. Fabry-Perots have a high light throughput even when operating at high spectral resolution. Tthis enables the instrument to target a very short spectral region specific to methane. This large throughput enables operation with a short integration time allowing the instrument to measure over small regions of the surface permitting discrimination of small methane sources. While the orbit of the space station does not reach high latitudes where methane emission from the permafrost is a serious concern this pioneering instrument points the way for additional observations from platforms with higher orbital inclination to address the questions of climate change in the longer term.

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Space Applications
The Fabry Perot spectrometer in this investigation uses reflected sunlight to make its measurements, and can target a very short segment of the light spectrum that is specific to methane. This allows the instrument to measure small regions of Earth and pinpoint methane sources with great accuracy. Its location on the International Space Station (ISS) enables a nearly global view over a long period of time, enabling scientists to study seasonal variations in atmospheric methane.

Earth Applications
Methane concentrations have increased in the atmosphere in recent decades, but the reasons why are not well understood. Human-related emissions are the largest source of methane, including from livestock grazing, rice production, landfills and fossil fuel extraction and burning. These methane sources are located around the world, but the amount of methane produced in each region is unclear, which affects the accuracy of climate models. This investigation develops an innovative space instrument to measure methane around the world with great accuracy. Results will help answer key questions about the distribution of methane, which provides crucial input for computer models used to predict future climate change.

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Operational Requirements and Protocols

FPS is scheduled to operate for a minimum of one year to capture seasonal variations in atmospheric methane, with two years being a goal. The instrument can operate continuously, but some downtime due to the sharing of the STP-H5 data downlink is acceptable and expected. Infrequent downtime due to other ISS needs is also acceptable and no special accommodations are required for this instrument.

This instrument used reflected sunlight to make its measurements. As such it does not make observations on the dark half of an orbit. That said some dark observations are needed to monitor the long term stability and calibration of the instrument. It is also the case that the power requirements for the instrument are very modest so it may well be that it is left on continuously.

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Decadal Survey Recommendations

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Results/More Information

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Related Websites

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NASA Image: ISS050E052652 - Space Test Program-H5 (STP-H5). Photo taken during Expedition 50.

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