Category Archives: Satellite Watching

ESA sponsors AI competition to spot GEO objects in low-cost telescope images

ESA sponsoring a new citizen science challenge at Kelvins- “ESA’s Advanced Concepts Competitions”. In the spotGEO Challenge, held in partnership with the  University of Adelaide,

… you are asked to develop an algorithm to detect Geostationary orbiting objects from simple png images (or frames) acquired by an unknown, low-cost ground-based telescope. Can you learn on how to cope with cloud cover, atmospheric/weather effects, light pollution, sensor noise/defects, star occlusions and more?

Check out the problem description, the dataset and the starter-kit (the dataset and the starter kit will only be available at the competition start date).

The start date is June 8, 2020. Here’s the official announcement from ESA:

Telescope-peering AI challenged to spot mystery space objects

“Artificial objects in or near geostationary orbit appear stationary or nearly stationary compared to the background stars, which appear to move due to Earth’s rotation, as shown in this sequence of observed images.” Credits: ESA/Univ. Adelaide

ESA’s latest public competition challenges ‘citizen scientists’ to combine AI with observations from low-cost telescopes to pick out mystery objects in and around geostationary orbit, thousands of kilometres above Earth.

Geostationary orbit is also known as the ‘Clarke belt’ – science fiction writer Sir Arthur C Clarke forecast it back in 1945. The further up that satellites orbit, the slower they need to travel to overcome Earth’s gravity. Orbiting at approximately 36 000 km altitude directly above the equator, satellite velocity precisely matches Earth’s rotation, enabling them hover above the same spots in the sky.

The result has been called the most valuable real estate in our solar system: a 265 000 km ring of telecommunications, meteorology and other satellites around our planet, carefully regulated by the International Telecommunication Union.

Despite its economic value however, geostationary orbit – as well as adjacent ‘geosynchronous’ orbits – must contend with the same problems of space debris also seen in lower orbits. ESA and other space agencies perform regular monitoring to identify and track potentially-hazardous debris items. This is usually done using either high-power radar or high-performance astronomical telescopes.

“Geostationary orbit is generally well managed and documented, partly because of its immense practical and commercial value,” notes Tat-Jun Chin of the University of Adelaide, partnering with ESA on the competition. “However, precisely because of that value we should put more efforts into further understanding and protecting it.”

Dario Izzo of ESA’s Advanced Concepts Team (ACT) adds:

“So, for our new ‘spotGEO’ competition, we want to see how well low-cost telescopes combined with tailored AI algorithms can identify ‘resident space objects’ at these altitudes.”

Competition entrants will receive a dataset made up of sets of five sequential images of unspecified segments of the geostationary belt, then challenged to pick out artificial objects against the surrounding stars.

This small telescope at the Univ. of Adelaide was used to “gather imagery of geostationary artificial objects for ESA’s GEOspot competition”. Credits: Univ. Adelaide/ESA

In theory this is made easier because such objects will remain static (or nearly static) compared to the background starfield, which appears to move because of Earth’s rotation. In practice, with atmospheric distortion and an approximately 40-second exposure time for each single image the objects will be smeared out and dimmed. Clouds, light pollution and sensor noise also add to the challenge.

“The sheer distance between the observer and the target objects makes this a difficult problem,” adds Dario.

“Each pixel observed at this altitude corresponds to an arc length of about 800 m – so the objects of interest are much smaller than a single pixel. But success should help us keep better watch on this essential region of space around our planet.”

Tat-Jun Chin and his team made contact with the ACT after winning the Pose Estimation Challenge, their previous space-themed AI competition, on estimating the orientation of distant satellites from a dataset of still images.

“Deep learning algorithms can be trained through such datasets to detect visual features of interest,” he notes. “Researchers in AI – particularly computer vision and machine learning – understand that having common datasets is vital towards making progress. These allow different methods to be compared objectively, so that the community can learn the best practices then apply them for their respective problems.

“Generally speaking, sharing datasets in space research is not so common, but the excellent Kelvins competitions are changing this, and after getting to know the ACT we decided to contribute our own.”

The University of Adelaide team coincidentally acquired these images during an observing campaign during the last Australian summer, so that forest fire smoke adds to the observing difficulty.

This is the latest competition hosted at the ACT’s Kelvins website, named after the temperature unit of measurement – with the idea that competitors should aim to reach the lowest possible error, as close as possible to absolute zero. The spotGEO dataset will be available there from 8 June, at the start of the three-month competition.

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Amateur sky watcher finds a long silent NASA science satellite talking again

Scott Tilley, an “amateur visual and radio astronomer”, recently discovered that a NASA science satellite that went silent in 2005 had begun transmitting again: Amateur astronomer discovers a revived NASA satellite | Science/AAAS

The astronomer, Scott Tilley, spends his free time following the radio signals from spy satellites. On this occasion, he was searching in high-Earth orbit for evidence of Zuma, a classified U.S. satellite that’s believed to have failed after launch. But rather than discovering Zuma, Tilley picked up a signal from a satellite labeled “2000-017A,” which he knew corresponded to NASA’s IMAGE satellite. Launched in 2000 and then left for dead in December 2005, the $150 million mission was back broadcasting. It just needed someone to listen.

Scientists who had worked previously on the IMAGE ( Imager for Magnetopause-to-Aurora Global Exploration) project are hoping to resume their studies with the satellite, which had been quite productive:

Prior to its failure, IMAGE was already considered a successful mission. The half-ton satellite’s instruments served as a sort of telescope, providing a global view of charged particles captured in Earth’s magnetic field. IMAGE’s instruments captured energetic neutral particles ejected by collisions of atoms in the inner magnetosphere, creating a broad-scale picture of that region and its interactions with the sun. It’s a capability that has never been replaced, Reiff says. “It is really invaluable for now-casting space weather and really understanding the global response of the magnetosphere to solar storms.”

During its extended mission, however, IMAGE’s signal winked out just before Christmas in 2005. The mission had been working perfectly up to that point; NASA eventually attributed the loss to a misfire of the controller providing power to the satellite’s transponder. It remained possible, however, that IMAGE could reset itself during points in its orbit when Earth eclipsed its solar panels for an extended time, draining its batteries. Such eclipses occurred last year—and 5 years ago—perhaps triggering its rebirth.

More at


Catch sight of “The Humanity Star” while it is in orbit

The Electron rocket launched last weekend from New Zealand by Rocket Lab had an unannounced payload aboard in addition to three small commercial spacecraft.  The Humanity Star is a

a bright, blinking satellite now orbiting Earth, visible to the naked eye in the night sky. Launched on #StillTesting, The Humanity Star is designed to encourage everyone to look up and consider our place in the universe. 

More about the project:

Visible from space with the naked eye, the Humanity Star is a highly reflective satellite that blinks brightly across the night sky to create a shared experience for everyone on the planet.

Created by Rocket Lab founder and CEO Peter Beck, the Humanity Star is a geodesic sphere made from carbon fibre with 65 highly reflective panels. It spins rapidly, reflecting the sun’s rays back to Earth, creating a flashing light that can be seen against a backdrop of stars.

Orbiting the Earth every 90 minutes and visible from anywhere on the globe, the Humanity Star is designed to be a bright symbol and reminder to all on Earth about our fragile place in the universe.

The sphere will stay in orbit for about 9 months. You can use the tracking app on the website to find when it will pass over your location.


Russian student satellite will shine bright in the night sky

A Russian student satellite was recently launched (along with 72 other satellites) into low earth orbit (LEO). Mayak is Russia’s first crowdfunded satellite project. The primary goal is to demonstrate that a small satellite can be de-orbited passively by deploying a large form that greatly increases the drag of the spacecraft as it passes through the extremely thin upper atmosphere in LEO.

Mayak, which is about the size of a loaf of bread (10cm x 10cm x 34 cm),  will inflate a tetrahedron-shaped form covered in reflective sheets. This will not only increase its drag but will also make it very bright in the night sky: Almost as Bright as the Moon? New Satellite Might Light Up the Sky – Sky & Telescope.

Each surface is four square meters on a side and should be readily visible from the ground on a twilight pass. In fact, the team claims, Mayak will be the “brightest shooting star” once unfurled, almost as bright as the full Moon at magnitude –10. Mayak could be visible in bright twilight and perhaps even during daytime passes as well.

The satellite tracking website Heavens-Above has created a Mayak tracking tool that will tell you when Mayak will pass over your location.

The plan is to fly Mayak in a stabilized mode for the first four weeks, then set it tumbling on all three axes, setting off a brilliant twinkling pattern. The team’s site mentions using brightness estimations from Mayak to gather information about air density at high altitude and to calibrate brightness estimations for future satellites.

The reflector will also speed up reentry once deployed, utilizing both solar wind pressure and atmospheric drag. Such devices may become a standard feature on future satellites, enabling them to de-orbit shortly after their mission ends rather than adding to the growing tally of space junk in low-Earth orbit. Nanosail-D2 tested a similar technology in 2011, and another mission recently dispatched from the International Space Station, InflateSail, is currently testing the same method.

The University of Toronto’s CanX-7  satellite, launched last September, deployed a drag sail in May and it quickly demonstrated its de-orbiting effect.

Here is a video of the launch of the Soyuz rocket that  put the 73 satellites into orbit: