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Oxygen in Planetary Biospheres

The Green Bank Blumberg Astrobiology workshops are supported by a grant from Unither Bioelectronique, in honor of Dr. Barry Blumberg, the late Chairman of its corporate parent’s Scientific Advisory Board.

May 5-7, 2023 at the Green Bank Observatory (GBO) in Green Bank, WV

Nobel Laureate Baruch S. “Barry” Blumberg (1925-2011). Founding Director of the NASA Astrobiology Institute

I understood that my mandate was to establish a basic science organization that could discover and understand natural phenomena that related to early life and to life elsewhere.

Barry Blumberg, on his appointment as founding director of the NASA Astrobiology Institute (NAI).

Earth, the only planet we know of with life (and with scientists who hold workshops to discuss planets and life) is thoroughly and anomalously oxidized – in its atmosphere, mineralogy and biosphere. Clearly, photosynthetically-released oxygen, fueled by a nearby star, is sufficient to support a robust and diverse biosphere. But is it necessary? If so, is it a “hard step” towards single-and multi-celled eukaryotes (animals and plants), or their extraterrestrial analogs (“complex life”), including cognitive and technological life? Oxygen is commonly discussed as a biosignature. The rise of oxygen, as both an energetic “fuel” and the source of an ozone UV screen, is seen as key to Earth’s development of complex life. Yet Earth’s biosphere predates its contemporary atmospheric composition, and given astrobiology’s “N=1” problem, do we know enough to generalize this requirement?  Should Earth’s history, which is marked by a geologically sudden rise of metabolically important atmospheric oxygen, be mirrored elsewhere? Are there astrophysical contexts and locations which favor the development of oxygenated planetary biospheres?

This 3-day workshop at the Green Bank Observatory will focus on topics related to the role of oxygen in the universe, planets, and life, and how the rise of oxygen on Earth may (or may not) likely have analogs on other planets.  Attendance is limited to 50 participants, by application only, and all registration and travel expenses will be covered. 

Recognizing the challenges the pandemic has presented for networking over the past several years, this workshop will have a strong focus on early career researchers and will have broad international participation. Presenters are encouraged to gear their talks to an interdisciplinary audience, eschewing the trees of internecine disciplinary debates for the forest of broader understanding.

Topics covered may include:

  • Oxygenation events in planetary histories.
  • The origin of oxygenic photosynthesis.
  • Planetary oxygenation and the development of biological complexity. 
  • Alternatives to oxygen: complex life and atmospheric radiation screens on abiotic planets?
  • Oxygen as a biosignature.
  • False positives.
  • How do biosignatures change with atmospheric redox state?.
  • Exoplanet modeling and observations.
  • Atmospheric evolution.
  • The astrophysical and astrochemical context for biological origin and evolution.

This list is not intended to be comprehensive or definitive; we encourage those working on any related problems not listed here to apply.

Meeting Leads

  • Lynn Rothschild
  • David Grinspoon
  • Jenn Macalady
  • Jason Wright


  • Shawn Domigal-Goldman
  • David Catling
  • Kevin Zahnle
  • Lisa Kaltenegger
  • Sonny Harman
  • Dan Mills
  • Elisa Merz
  • Stephanie Olson


We have a wide and varied list of participants attending this workshop coming from fields covering everything from the arts to hydrogeology.

Astrobio2023 Workshop group photo (more on our Flickr site)


Thursday 4 May12:30Lunch in the Cafeteria
19:00Informal Reception — Drake Lounge
Session 1Oxygen and Biospheric Evolution — Jansky Lab AuditoriumChair: Lisa Kaltenegger
8:00Breakfast in the Cafeteria
8:45Opening: Welcome/AnnouncementsLOC
09:10–10:30Planetary ‘oxygenation time’ and the ‘hard-steps’ model – why only one can be rightDan Mills
Photochemical modelling of atmospheric oxygen over Earth’s middle history and its co-evolution with the biosphereBethan Gregory
How does competition between phototrophs shape the oxygen content on habitable worlds?Ligia Fonseca Coelho
Is planetary oxygenation common or rare?McCullen Sandora
10:30Coffee Break
Session 211:00–12:20Did early eukaryotes inhabit oxygenated environments? Constraints from the geological recordMax Lechte
The combined evolution of Earth’s atmospheric O2 and N2: integrating geochemical and modeling resultsBenjamin Johnson
Timing the advent of aerobic respiration with cytochrome oxidasesFatima Husein
Oxygenation of High-Obliquity WorldsStephanie Olson
12:30Lunch in the Cafeteria
13:30GBT Tour
15:30Coffee Break
Session 316:00–17:20Barry BlumbergMartine Rothblatt
Understanding the Evolutionary History of Oxygen-regulated Gene Families in BacteriaJaime Cordova
Biological regulation of Earth’s early atmosphereAubrey Zerkle
Modeling O2 Seasonality on Early Earth and Earth-like ExoplanetsEmilie Lafleche
17:30Dinner in the Cafeteria
Evening Session19:00Impact of Science Fiction on Spaceflight History — Science Center AuditorumMichael Benson
20:30Drake Lounge
Session 4Origin and Evolution of Photosynthesis — Jansky Lab AuditoriumChair: Dan Mills
8:00Breakfast in the Cafeteria
09:00–10:20Variable and evolving energetic constraints on photosynthesis at the molecular and planetary scalesNancy Kiang
Characterization and quantification of far red oxygen oxygenic production rates in Acaryochloris spp.José Orench-Benvenutti
Geological and geochemical evidence of oxygenic photosynthesis at 3.2 billion years ago: constraints from banded iron formations at Barberton, S. Africa.Hikari Saito
Success is more than photosynthesis: The activity of oxygenic phototrophs in the darkElisa Merz
10:30Coffee Break
Session 5Great Oxidation Event and BiosignaturesTBD
11:00–12:20Rapid Timescale for an Oxic Transition During the Great Oxidation Event (GOE) and the Instability of Low Atmospheric O2Nick Wogan
Insight into the biosphere during the GOEErica Barlow
Changing oxygen levels through the PhanerozoicRebecca Payne
Earth’s Geophysical Evolution and the Role of the Marine Biosphere in Surface OxygenationAshika Capirala
12:30Lunch in the Cafeteria
Session 614:00–15:30Life and the oxygenation of early Earth: A case study from a 2.4-2.2 Ga microbialite reef complex in Western AustraliaGeorgia Soares
Oxygen production due to virus infectionKen Stedman
How long has Earth’s biosphere been detectable?Mark Claire
A whiff of oxygenLisa Kaltenegger
15:30Coffee Break
Session 716:00–17:20Photochemical Controls on Biosignature Gas Accumulation in Habitable Planet Atmospheres.Sukrit Ranjan
Calculating the ozone column depth in Earth’s early atmosphereAoshuang Ji
The fine structure lines of isotopically heavy atomic oxygen – or: On the boundary of atmospheric biosignaturesHelmut Weisemeyer
Bioverse: Characterizing the runaway greenhouse transition in Earth-sized exoplanets.Martin Schlecker
Panel Discussion19:00Astrobiology and the Human Experience — Science Center AuditorumRothblatt; Haramia; de Paulis; Tatel; Benson, Pomerance
20:30Drake Lounge
Session 8Astronomical Context — Jansky Lab AuditoriumChair: Stephanie Olson
8:00Breakfast in the Cafeteria
09:00–10:20SETI/AstrobiologyChelsea Haramia
Sonification of data for the detection of lifeMatt Schaub / Tim Spuck
Disequilibrium as a sign of extraterrestrial life revisited: Influences of photosynthesis, oxygen, and advanced life.David Catling
Oxygen and TechnosignaturesRavi Kopparapu
10:30Coffee Break
Session 9False PositivesChair: Elisa Merz
11:00–12:20Habitable Worlds Observatory: Target Stars and Considerations for the Astro2020-Recommended Survey for Potentially Habitable WorldsEric Mamajek
The Interplay between Iodine and the Evolution of Life on EarthJingjun Liu
Is abundant atmospheric oxygen a common outcome of lifeless planetary evolution?Joshua Krissansen-Totton
Abiotic oxygen in the atmospheres of Venus-like exoplanetsMichael Wong
12:30Lunch in the Cafeteria
Session 1014:00–15:20Exploring Oxygen Production due to Thermal Atmospheric Escape on the TRAPPIST-1 PlanetsMegan Gialluca
Formation of manganese oxides due to active halogen cycling and not oxygen on early MarsKaushick Mitra
Oxygen False Positives: A Review of Putative Abiotic O2 MechanismsSonny Harman
Cryptic photosynthesis: Planetary oxygen production with no surface signature of lifeCharles Cockell
15:30Coffee Break
Session 1116:00–17:00Desert lichens and cyanobacteria suggest that planets without ozone shield are not necessarily uninhabitableTejinder Singh
Isotopically depleted carbon solids as false positive biosignaturesbefore the rise of oxygenJulia DeMarines
Wrap UpJenn Macalady
17:30Dinner in the Cafeteria
19:00Talks from the Future — Jansky Auditorium
20:30Drake Lounge

Breakfast is at 7 a.m.

Shuttle departs for Dulles (IAD) at 8:00

Travel Logistics

Green Bank is located in an isolated valley in the Appalachian mountains of West Virginia, just a few miles from the border with Virginia. It is about a 4-hour door-to-door drive from Washington, Dulles Airport (IAD), which we recommend that you use. Please book air travel by April 13. Review this documentation outlining travel requirements.

The Workshop will begin with dinner on Thursday, May 4. If you arrive at Dulles airport on Thursday, we will provide transportation to Green Bank via the Observatory shuttle. One shuttle will leave Dulles at 12 noon, and another shuttle will leave Dulles at 4 pm. The shuttle will also be available for transportation back to Dulles Airport after the workshop on the morning of Monday, May 8, and Tuesday, May 9. The return shuttles will depart Green Bank at 8 am and arrive at Dulles by 12 noon on both Monday and Tuesday. If you prefer to use another airport and/or rent a car to drive to Green Bank, that is certainly an option. The Workshop will cover your transportation costs regardless. Recommended driving directions can be found on the Observatory website.

A Travel Authorization Form (check your email for a link to this form) must be completed to obtain reimbursement. Reimbursement will be made for the cost of economy airfare on a U.S. flag carrier or an airline that “code shares” with a U.S. flag carrier. Reimbursement will be made for a compact rental car, or larger car if used by two or more travelers. Keep track of receipts for other transportation expenses — bus, taxi, tolls, parking, etc. You will receive a standard per diem for meals and incidental expenses, so there is no need to save restaurant receipts. If you are not seeking travel reimbursement, do not return the form. If you are combining the trip to Green Bank with other travel, simply list the dates of the other travel in the “Vacation Travel” section of the Authorization so that we will know not to reimburse expenses on those days. Dates on the Travel Authorization can be your best estimate at this time.

In general, we are not planning to provide cash advances, but if this will cause a hardship please let us know. We will be able to provide lodging and meals at Green Bank for an accompanying person sharing your room.

Housing will be in private rooms at several locations: the Observatory Residence Hall, Observatory-owned houses on the Observatory Grounds, nearby B&Bs, and rooms at a commercial lodge. The lodge is about 10 miles from the Observatory; a shuttle will run there several times a day. Each room has a private bathroom. We ask for your gender identification to assist in assigning housing. We will provide you with specific information about your housing well in advance of the workshop.

Green Bank is in the National Radio Quiet Zone and there are restrictions on wireless technology at the Observatory. There is no cell/mobile phone service at the Observatory or in nearby communities, and wireless devices of any sort must be disabled at the Observatory. You will have access to high-speed internet at the workshop and in your room through a wired ethernet connection. The workshop will take place in a fully-equipped auditorium with connections to video projectors and the internet. In short, we have ample internet connectivity, but it is through wired, not wireless, means. We do have some connectors that mate common laptop ports to ethernet (e.g., USB, Thunderbolt) but we recommend that you check that your laptop can connect via ethernet before arriving in Green Bank.

Streaming Link (View Only): https://nrao-edu.zoom.us/j/92720168271

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