Posted on February 2nd, 2021

Our Changing Landscape – The Arecibo Observatory

Click on the image above to see an animation of 3-meter natural color PlanetScope imagery collected over the Arecibo Observatory on August 6 and 13, and December 1 and 6, 2020. In this animation, you can see the entire progression of the Arecibo Observatory from fully functional to collapsed. The August 6th image shows a fully functional receiver platform and dish below, and then by the 13th you can see a hole below the observation tower after the failure of the first support cable. The December 1st image (sorry for its shifted position!) was collected right after the massive failure of the platform which tore a large hole in the dish panels below. By December 6th, it appears that the gash in the aluminum dish panels has grown larger. (Images Courtesy: © Planet 2021)

In this monthly feature, we span the globe to examine Our Changing Landscape with a time series of medium-resolution PlanetScope satellite imagery. The PlanetScope constellation dates back to 2016 and collects hundreds of millions of square kilometers of four and five-band 3-meter imagery daily! In January we checked out the devastation caused by a late-season Atlantic hurricane, and for the February edition of Our Changing Landscape we focus on the demise of one of the world’s most important telescopes, the Arecibo Observatory in Puerto Rico.

The PlanetScope Microsat Constellation

PlanetScope is a constellation of more than 150 microsats referred to individually as Doves. Each Dove is able to collect up to 20,000 square kilometers (sq km) per day of 3-meter (m) 4-band multispectral (i.e. blue, green, red and near-infrared [NIR]) imagery; and newly launched SuperDoves collect 5-band multispectral adding in valuable red-edge spectral data. Across the constellation, PlanetScope is archiving more than 200 million sq km of medium-resolution imagery a day, making it the go to source for daily imagery over most locations. This massive archive dates back to 2016, offering the most complete and continuous record of spatial data on the planet since the start of the constellation’s ongoing launch schedule. Collecting 3-meter multispectral imagery is the equivalent of ‘high-resolution’ multispectral data imaged by a 75-centimer (cm) satellite (as this satellite would feature 75-cm panchromatic and 3-m multispectral), making PlanetScope an extremely competitively priced option at just $1.80 per sq km. With well registered images and nearly daily collections of most locations, PlanetScope is the ideal imagery source for this current-events focused series, Our Changing Landscape.

The Collapse of the Arecibo Observatory in Puerto Rico

Built on 120-acres of federally-owned forests in northwest Puerto Rico, construction of the Arecibo Observatory started in 1960 with $9.7-million in funding from the US Department of Defense. Opened in 1963, Arecibo was the world’s largest single-aperture telescope for 53 years, only surpassed in size by China’s Five-hundred-meter Aperture Spherical Telescope (FAST) during July 2016. Built in a natural depression, the Arecibo Observatory was approximately 1,000-feet (305-meters) wide and 167-feet (51-meters) deep. The telescope itself was comprised of 40,000 aluminum panels covering 20 acres with a 900-ton radar receiver suspended 450-feet (137-meters) above the reflective panels.

And yes, as you might have noticed, we are purposely using past tense here to describe the Arecibo Observatory as it crashed to the ground at 8AM local time on December 1, 2020. The loss to the international space exploration community is hard to fathom; and equally hard to fathom is the sad chain of events that led to the observatory’s ultimate demise – as was described last month in Katie’s Out of This World article. Plagued by a lack of funding over its decades of operation, the beginning of the end of Arecibo started on August 10th at 2:45AM when a 3-inch support cable snapped, damaging 6 to 8 aluminum panels. Apparently, the extra pressure on the remaining supporting cables ultimately led to multiple failures December 1st when the 900-ton receiver platform came crashing down into the aluminum panels below. While future plans for the site of the Arecibo Observatory are still unclear, it is time to turn to the 3-meter PlanetScope archive to track the sad demise of the world’s second largest telescope.

If you would like to find out more about using 3-meter PlanetScope imagery for your academic studies, engineering projects or any landscape analysis, let us know at [email protected] or (303) 993-3863.

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