European Space Agency Flickr Update

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Don Kessler
20-04-2017 04:33 PM CEST

europeanspaceagency posted a photo:

Don Kessler

Operations image of the week:

Retired astrophysicist and former NASA scientist Donald Kessler seen attending the European Conference on Space Debris at ESA in Darmstadt, Germany, on 18 April 2017.

Since 1957, more than 5250 space launches have led to an orbiting population today of more than 23 000 tracked debris objects.

Only about 1200 are working satellites. The remaining are classified as space debris and no longer serve any useful purpose. A large percentage of the routinely tracked objects are fragments from the approximately 290 breakups, explosions and collisions of satellites or rocket bodies that are known to have occurred.

An estimated 750 000 objects larger than 1 cm and a staggering 166 million pieces larger than 1 mm are thought to reside in commercially and scientifically valuable Earth orbits.

Relative orbital speeds of up 56 000 km/h mean that even centimetre-sized debris can seriously damage or disable a working satellite, and collisions with objects larger than 10 cm will lead to catastrophic break-ups, releasing clouds of hazardous debris fragments that will go on to cause further catastrophic collisions, potentially leading to an unstable debris environment in some orbital regions.

This run-away scenario is known as the “Kessler syndrome” because it was first postulated by Don in 1978.

Credit: ESA/J. Mai

Taking Tim’s breath away
20-04-2017 12:43 PM CEST

europeanspaceagency posted a photo:

Taking Tim's breath away

Human spaceflight and robotic exploration image of the week:

The stellar views from the International Space Station are not the only things to take an astronaut’s breath away: devices like this are measuring astronauts’ breath to determine the health of their lungs. ESA astronaut Tim Peake took part in the Airway Monitoring experiment during his Principia mission in 2016.

Developed by researchers at the Karolinska Institutet in Sweden, the experiment draws on a study of airway inflammation that ran on the Station from 2005 to 2008.

The analyser measures the amount of nitric oxide in exhaled air – a signalling molecule produced in the lungs to help regulate blood vessels. Too much nitric oxide suggests inflammation. Causes can be environmental, like dust or pollutants, or biological, such as asthma – at least on Earth, but what happens in space?

Researchers compare measurements from astronauts taken before their flights to those taken in space to understand the effects of weightlessness on airway health. Astronauts in space are essentially fish out of water. Understanding how to track, diagnose and treat lung inflammations is important for their safety.

The experiment began with ESA astronaut Samantha Cristofretti’s 2015 mission and measurements have been gathered by six astronauts. Four more astronauts will conduct the experiment next year.

Credit: ESA/NASA

Proba-1 images Calanda reservoir
20-04-2017 12:38 PM CEST

europeanspaceagency posted a photo:

Proba-1 images Calanda reservoir

Technology image of the week:

The blue of the Calanda reservoir amid the rugged landscape of northeastern Spain, as seen by ESA’s oldest – and one of its smallest – Earth-observing missions, Proba-1, midway through its 15th year of operations.

Located around 120 km southeast of the city of Zaragoza, and built within a surrounding gorge, the reservoir is used for agricultural irrigation and fishing. The town of Calanda is visible at the top of the image.

Researchers can use Proba-1’s hyperspectral camera to gather data on the reservoir’s water quality and phytoplankton content.

The cubic-metre Proba-1 is the first in ESA’s series of satellites aimed at flight-testing new space technologies. It was launched on 22 October 2001 but is still going strong, having since been reassigned to ESA’s Earth observation duties.

Proba-1’s main hyperspectral CHRIS imager records 15 m-resolution scenes across a programmable selection of up to 62 spectral bands, from a variety of viewing angles. It is supplemented by a 5 m-resolution black-and-white microcamera.

Other innovations include what were then novel gallium-arsenide solar cells, the use of startrackers for gyroless attitude control, one of the first lithium-ion batteries – now the longest such item operating in orbit – and one of ESA’s first ERC32 microprocessors to run Proba-1’s agile computer.

For more background on Proba-1, read this celebration in the ESA Bulletin.

Proba-1 led the way for the Sun-monitoring Proba-2 in 2009, the vegetation-tracking Proba-V in 2013 and the Proba-3 precise formation-flying mission planned for 2019.

Credit: ESA, CC BY-SA 3.0 IGO

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