Research project Oxygen and its Role In Generating and Influencing Nightglow (ORIGIN)
The ORIGIN rocket project addresses the Earth's nightglow, a global emission layer that is the result of reactions between atomic oxygen and other atmospheric species in the upper mesosphere and lower thermosphere, at altitudes between 80 and 110 km.
The Earth's airglow (nightglow and dayglow) continues to be a source of inspiration for both basic physics and applied atmospheric research. With the ORIGIN project (with two sounding rocket launches from Esrange Space Center in January 2025), we intend to return to some of the basic questions, with a particular focus on atomic oxygen in the upper mesosphere and lower thermosphere: we revisit the ability to determine atomic oxygen from measurements of the major nightglow emissions O2 Atmospheric Band, O Green Line, and OH Meinel. Thus, we directly compare three important techniques for remote sensing of atomic oxygen, while at the same time assessing underlying photochemical mechanisms and performing independent simultaneous measurements of key species and atmospheric background conditions.
Project description
Atomic oxygen is the major carrier of chemical energy in the mesosphere and lower thermosphere, thus controlling much of the chemistry, energy budget and radiative properties of this part of the atmosphere. Major source of atomic oxygen in the region is O2 photolysis in the spectral range of the Schuman-Runge continuum in the lower thermosphere. Transport processes from global circulation to local turbulence transport O down to mesospheric altitudes and cause substantial variability over a wide range of spatial and temporal scales. In addition, the Chapman photochemical cycle describes the conversion within the odd oxygen family (Ox = O, O3) with a strong diurnal variation in the mesosphere. The ability to accurately measure the local distribution of atomic oxygen is thus crucial for studies of the Earth's mesosphere and lower thermosphere.
The chemical energy stored in odd oxygen can be converted through various chemical reaction schemes, including various excited states of O and O2, odd hydrogen species. An important result of these reactions is the release of energy in terms of the Earth's airglow. Indeed, observations of airglow during day (dayglow) or night (nightglow) are a powerful tool for studies of basic molecular physics, photochemistry, atmospheric composition, and energetics. Since the processes giving rise to the airglow emissions are modified by atmospheric dynamics, a strongly emerging field is also the use of airglow as a tracer for atmospheric wave activity and circulation patterns.
Several nightglow emission processes are today used by remote sensing techniques to infer atomic oxygen and draw conclusions about the state of the atmosphere. A basic requirement for inferring atomic oxygen from nightglow measurements is accurate knowledge about the underlying reaction schemes and reaction coefficients linking the emissions and the O densities.
With ORIGIN our goal is a quantitative assessment of today's standard nightglow model. This model has its origins in the ETON rocket project from 1982, and has subsequently been extended in various directions, very much driven by recent applications in satellite-borne remote sensing. ORIGIN will be based on close collaboration with research groups employing such nightglow models, both within the ORIGIN team and beyond. Decisive is also to incorporate recent laboratory results. Most prominently, an important focus of ORIGIN will be on the recently discovered source of excited O(1D) through the reaction of vibrationally excited hydroxyl OH(v≥5) and ground state oxygen O(3P). This discovery was very surprising as it adds a photochemical source of O(1D) at nighttime. This constitutes thus a basic modification of established reaction schemes, and provides an unexpected link between the O2 Atmospheric Band and OH Meinel nightglow emissions. The co-analysis of OH vibrational levels and O2/O/OH nightglow emissions is thus a scientific objective of ORIGIN.
In summary, the following major scientific objectives are defined for ORIGIN:
- To what extent do current versions of the "ETON standard model" provide a quantitative relationship between major nightglow emissions, key constituents and atmospheric background conditions?
- How efficient is the newly discovered reaction path OH(v≥5) + O as a nighttime source of O(1D), and how does this affect established remote sensing techniques for atomic oxygen?
- How can we apply our knowledge to provide optimal tools for atomic oxygen retrievals from rocket-borne and satellite-borne measurements?
Decisive for ORIGIN is to perform all measurements simultaneously and with the high spatial resolution that only is achievable on a sounding rocket. In addition to the relevant nightglow emissions, in situ measurements target atomic oxygen by optical and electrolytic techniques, atomic hydrogen, atmospheric temperature and density, as well as ionospheric conditions. Complementary to the rocketborne experiments, ORIGIN will employ a broad suite of ground-based instrumentation, including the Esrange lidar, the ALIS_4D All-sky imager network and a high-resolution spectrograph contributed by University of Massachusetts. We aim to perform the ORIGIN oxygen/hydroxyl nightglow study during two distinctly different atmospheric conditions. To this end, we will adapt the cost-efficient launch concept successfully developed by SSC Space for the O-STATES rocket campaign in 2015: after a first launch, the scientific payload is recovered, refurbished on site, and launched a second time.
Improving our quantitative knowledge of the above airglow features is not only a basis for understanding the underlying reaction schemes. It also facilitates the use of these emissions for observing atmospheric structures and dynamics, which today is a primary goal of remote sensing from space and from the ground. This relates in particular to our ongoing quest for better understanding wave interactions in the middle atmosphere, including the MATS satellite with its tomographic studies of the O2 Atmospheric Band.
Project members
Project managers
Jonas Hedin
Researcher
Members
Donal Murtagh
Professor
Jacek Stegman
Researcher
Joachim Dillner
Research engineer
Jörg Gumbel
Professor of Atmospheric physics
Konstantinos Kalogerakis
Linda Megner
Researcher, docent
Nickolay Ivchenko
Associate professor