CubeSats to measure light pollution

CubeSats to measure light pollution

I had the fortune of being able to offer some examples of environmental applications in a paper by Dee Pack and Brian Hardy from Aerospace Corporation for the Small Satellite Conference this summer in Utah.  We (mostly they) show the feasibility of using small satellites to measure upward radiance from Earth at night, with examples ranging from the Middle East to Southern California.  I’m glad to have offered the concept of “darkest path” modeling for wildlife connectivity and perspectives on the usefulness of spectral information at this scale. The work we have been doing with the VIIRS Day-Night Band shows up for the identification of a very bright greenhouse on the Oxnard Plain.  Here is the citation, abstract, and download link.

Pack, D. W., B. S. Hardy, and T. Longcore. 2017. Studying Earth at night from CubeSats. Proceedings of the 31st Annual AIAA/USU Conference on Small Satellites, Leo Missions, SSC17-WK-35.

This paper presents examples of the latest imaging data of the Earth at night from multiple CubeSat platforms. Beginning in 2012, with AeroCube-4, The Aerospace Corporation has launched multiple CubeSat platforms in different orbits equipped with a common suite of CMOS sensors. Originally designed as utility cameras to assist with attitude control system studies and star sensor development, we have been using these simple camera sensors to image the Earth at night since 2014. Our initial work focused on observing nighttime urban lights and global gas flare signals at higher resolution than is possible with the VIIRS sensor. To achieve optimum sensitivity and resolution, orbital motion is compensated for via the use of on-board reaction wheels to perform point-and-stare experiments, often with multiple frame exposures as the sensor moves in orbit. Ground sample distances for these systems range from approximately 100 to 130 meters for the narrow-field-of-view cameras, to 500 meters for the medium-field-of-view cameras. In our initial work, we demonstrated that CMOS sensors flown on AeroCube satellites can achieve a nighttime light detection sensitivity on the order of 20 nW-cm-2-sr-1. This resolution and sensitivity allows for detection of urban lighting, road networks, major infrastructure illumination, natural gas flares, and other phenomena of interest. For wide-area surveys, we can also program our cameras to observe regions of interest and co-add pixels to reduce the data bandwidth. This allows for a greater number of frames to be collected and downloaded. These results may then be used to task later satellite passes. Here, we present new examples of our nighttime Earth observation studies using CubeSats. These include: 1) detecting urban growth and change via repeat imaging, 2) investigating the utility of color observations, 3) spotting major sources of light pollution, 4) studying urban-wildland interface regions where lighting may be important to understanding wildlife corridors, 5) imaging lightning and cloud cover at night using wide-area imaging, 6) observations of the very bright lights of fishing boats, and 7) observing other interesting natural phenomenon, including airglow emissions, and the streaking caused by proton strikes in the South Atlantic Anomaly. Our ongoing work includes utilizing a diversity in overpass times from multiple satellites to observe nighttime scenes, imaging high-latitude cities not optimally accessed by the international space station’s cameras, and building a catalogue of observations of rapidly developing megacities and global infrastructure nodes. Data from CMOS sensors flown in common on 5 different AeroCubes in 4 different orbits have been collected. Our results show that enhanced CubeSat sensors can improve mapping of the human footprint in targeted regions via nighttime lights and contribute to better monitoring of: urban growth, light pollution, energy usage, the urban-wildland interface, the improvement of electrical power grids in developing countries, light-induced fisheries, and oil industry flare activity. Future CubeSat sensors should be able to contribute to nightlights monitoring efforts by organizations such as NOAA, NASA, ESA, the World Bank and others, and offer low-cost options for nighttime studies.

Spatial and Temporal Analysis of Nighttime Lighting In and Around National Parks


Yu Chuan Shan, Ben Banet, and I have been working the past couple of years on developing a monthly database of upward radiance from within and buffers around all of the National Park units in the United States.  They are presenting the research today at the USC undergraduate research symposium.  The results presented only scratch the surface of what we can do to analyze this high-resolution database over space and time.

Shan also put together a website to walk through the project.

The poster can be downloaded here. Please cite as:

Shan, Yu Chuan, Ben Banet, and Travis Longcore. 2017. Spatial and Temporal Analysis of Nighttime Lighting In and Around National Parks. USC Undergraduate Symposium for Scholarly and Creative Work (Los Angeles, April 12, 2017).

Unintentional Media Blitz

As a result of the new atlas of of artificial night sky brightness I ended up doing a lot of interviews for national and international outlets, including Science Magazine,, Christian Science Monitor, Scientific American, and USA Today.

Then the American Medical Association released a statement on LED lighting (for which I had provided some background information) and a few more stories came out in and Christian Science Monitor.

A couple of Los Angeles Times stories also happened to include me:

Rare toads (presumably) love him; off-roaders do not 

The sunset that takes an hour to go from date palms to to redwoods

Heading to New Orleans: Ecologically Sensitive Lighting Design

Landscape architects, mark your calendars.  I’ll be part of a joint presentation on Ecologically Sensitive Lighting Design that was just accepted to the American Society of Landscape Architects annual meeting in New Orleans this fall.  I teamed up with lighting designer Linnaea Tillett and lighting engineer Nancy Clanton, two of the top landscape lighting experts in the country on the session proposal.  We will use a case study format to explore approaches to landscape lighting (and not lighting…) that incorporate the psychology of place-making, consideration for nature, and technical advances in the field.

Boulder City Hall lighting design by Clanton and Associates.

Boulder City Hall lighting design by Clanton and Associates.

Optics and Photonics News Covers Environmental Impacts of Lighting

Optics and Photonics News Covers Environmental Impacts of Lighting

The message that lights can have environmental consequences becomes more and more mainstream. Optics and Photonics News this month has an article by freelance writer Jeff Hecht, with whom I’ve spoked for other stories before. His article is a multi-page spread and emphasizes both spectrum and intensity and their potential impacts, as well as the potential to mitigate those impacts by customizing both. Here’s my pull quote:

Longcore’s ideal would be very low blue to reduce wildlife impact, with only enough blue added to raise color temperature to 2700 K if necessary for good color rendering.

I actually think that most outdoor lighting can do without blue light and might put an “absolutely” before the “necessary” in the quote. Manufacturers are starting to deliver LEDs that cut out nearly all the blue light, have a reasonable color rendering index, and can be dimmed without an efficiency penalty.

Expert quote on exciting new light pollution research

Australian zoologist Kylie Robert and colleagues have published an exciting new paper on the disruption of breeding patterns and melatonin levels in a free-ranging native mammal. I had the chance to comment on the significance of this research for Science News and am delighted that Dr. Robert will also be presenting at the Annual General Meeting of the International Dark-Sky Association on November 15 in Phoenix. To my knowledge, this paper is one of the first showing these kinds of effects, such as lowered blood melatonin levels, in the field and joins recent work by Davide Dominoni, who showed impacts from night lighting on the physiology of wild birds.


A framework to assess evolutionary responses to anthropogenic light and sound

A framework to assess evolutionary responses to anthropogenic light and sound

John P. Swaddle*, Clinton D. Francis*, Jesse R. Barber, Caren B. Cooper, Christopher C.M. Kyba, Davide M. Dominoni, Graeme Shannon, Erik Aschehoug, Sarah E. Goodwin, Akito Y. Kawahara, David Luther, Kamiel Spoelstra, Margaret Voss, Travis Longcore


  • Anthropogenic light and sound are an important component of global change.
  • These stimuli often co-occur and may function synergistically.
  • The selection pressure of light and noise may drive the rate of evolutionary change.
  • We propose a framework to explore the ultimate consequences of noise and light exposure.


Trends in Ecology and Evolution

Human activities have caused a near-ubiquitous and evolutionarily-unprecedented increase in environmental sound levels and artificial night lighting. These stimuli reorganize communities by interfering with species-specific perception of time-cues, habitat features, and auditory and visual signals. Rapid evolutionary changes could occur in response to light and noise, given their magnitude, geographical extent, and degree to which they represent unprecedented environmental conditions. We present a framework for investigating anthropogenic light and noise as agents of selection, and as drivers of other evolutionary processes, to influence a range of behavioral and physiological traits such as phenological characters and sensory and signaling systems. In this context, opportunities abound for understanding contemporary and rapid evolution in response to human-caused environmental change.