Skip navigation
Share via:


Determine which geoengineering schemes are safe and effective by detecting and analysing (un)successful geoengineering schemes on exoplanets



~ 22% of sun-like stars have Earth-like exoplanets(6).  Advanced technological civilisations may exist on these, and may use geoengineering to induce positive or negative radiative forcing. Similarly, aliens may be involved in terraforming projects(3), to render other planets habitable.  Geoengineering schemes may affect the albedo, spectroscopy, polarisation, etc. of light observed from other planets.  Accordingly, detection via these or other methods may be viable..Observations of alien geoengineering may identify common technological approaches, which tend to be associated with well-controlled deployment and maintenance - therefore suggesting safe and stable methods for Earth.

Promising detection approaches, matched to geoengineering schemes include:

1. Transit spectroscopy to detect the existence of artificial 'supergreenhouse' gases in alien atmospheres (1, 3)

2. Spectropolarimetery to detect clouds and sulphate or other aerosols (extension of inferior methods already successfully used in reference 2).  Characteristic sulphate loading patterns may clearly indicate geoengineering, but marine cloud brightening may be harder to disentangle from natural processes.

3. Time series and statistical analysis of the above signals from a large number planets will narrow technological origin, purpose, lifespan, technological obsolescence, etc. of detected interventions. 

Category of the action


What actions do you propose?

1) Processing data from existing space/ground telescopes to optimise the chance of detecting exoplanet geoengineering and terraforming schemes.

2) Basic scientific research to improve our understanding of earth and solar system bodies, particularly as regards potential geoengineering impacts, to ensure we are better able to understand and direct our observations of exoplanets.  The LOUPE spectropolarimetry proposals for the ESA moon mission are particularly helpful in this regard.

3) Creation or modifications of new telescope projects aimed specifically at detection of geoengineering on exoplanets.

4) Roll out of the above at numerical scale, to observe large numbers of applicable planets. (This will not necessarily require any additional satellite build, as individual satellites can observe huge numbers of stars).

5) Creation of a socio-technological model to explain the deployment and management of observed geoengineering programmes on exoplanets.

6) Creation of plans for deployment of technologies on Earth which conform to the observed pattern of successful exoplanet deployments.

Who will take these actions?

The existing astronomy, astronometry and planetary research communities - with particular focus on major organisations, such as NASA and ESA.

The governance implications of this work require time series observations and/or the observation of large numbers of geoengineered planets, in order to establish reliable trends.  The intent would be to observe a predictable pattern of innovation, intervention and obsolescence in a climate engineering technology.  The commonly observed existence of a controlled deployment, long and predictable intervention, and a controlled termination are good signs.  A sudden termination, without deployment of alternative technologies (and particularly early in deployment), suggests that the observed methodology has either caused serious side effects, or has been concurrent with the collapse of the deploying civilisation. 

Whilst observing individual planets on decadal timescales may be instructive, it is unlikely that this alone will be enough to establish patterns.  In all likelihood, the observation of hundreds or thousands of geoengineered planets would be required to establish patterns which would allow us to predict the evolution of geoengineering technology programmes with any reliability.  However, once such predictions can be made, and tested against new discoveries, we will have a model for the evolution of the technology to guide technology governance.  For example, if we detect deployment of interventions which subsequently become ever more unstable over time, before ceasing suddenly, this would be an indication that a certain technology set would be socially and/or technologically unstable - and therefore that it should not be deployed.

Where will these actions be taken?

Observations will principally be in space, but the principle location for research collaboration will be in the academic environment.

What are other key benefits?

Detection of geoengineering will, as a by product, indicate advanced technological civilisations - and therefore perform the role of SETI.

What are the proposal’s costs?

There are  few direct cost implications.  Rather, this simply amounts to a refocusing of existing research priorities around a new target, ensuring the that observations and data processing is optimized for discovery of exoplanet geoengineering and terraforming.

Time line

Short - reprocess existing data; conduct basic research design new probes

Medium - launch new probes optimised for the detection of exoplanet geoengineering

Long - observing the periodicity, evolution, obsolescence or cancelation of alien geoengineering schemes

Related proposals


1.           arXiv:1406.3025 [astro-ph.EP]

2.           arXiv:1008.4800 [astro-ph.EP]

3.           doi:10.1073/pnas.051511598

4.           arXiv:1208.5489 [astro-ph.SR]

5.         arXiv:1010.2197 [astro-ph.EP]

6.          PNAS..11019273P.doi:10.1073/pnas.1319909110

7.           doi:10.1038/nature12888.

8.          doi:10.1006/asle.2002.0099.

9.           doi:10.1088/1748-9326/4/4/045102.

10.         doi:10.1089/ast.2006.0039.

11.          arXiv:1009.3071 [astro-ph.EP]