jeudi 27 juillet 2017

Trio Ready to Begin Space Mission Lasting till Mid-December










ISS - Expedition 52 Mission patch.

July 27, 2017

International Space Station (ISS). Animation Credit: NASA

It is less than one day before three new International Space Station crew members start a 4-1/2 month mission in space. The trio from Russia, United States and Italy will launch aboard the Soyuz MS-05 spacecraft Friday at 11:41 a.m. EDT from the Baikonur Cosmodrome in Kazakhstan.

Cosmonaut Sergey Ryazanskiy and astronauts Randy Bresnik and Paolo Nespoli will dock to the Rassvet module having left Earth just six hours and 19 minutes earlier. After pressure checks the hatches will open and the crew will fly into their new home. They will join their Expedition 52 crewmates Commander Fyodor Yurchikhin and Flight Engineers Peggy Whitson and Jack Fischer.


Image above: The Soyuz MS-05 rocket stands at its launch pad at the Baikonur Cosmodrome in Kazakhstan. Image Credits: NASA/Joel Kowsky.

Meanwhile, space research continues apace as scientists on the ground and the crew observe microgravity’s effects on humans, plants and animals. Research on the station also runs the gamut of physics, technology, earth observations and more, benefitting life on Earth and future crews in space.

All three crew members orbiting Earth today once again explored a lower body suit that has the potential to reverse the headward flow of body fluids in space. Whitson then studied new methods to manage liquid and gas mixtures on spacecraft life support systems. Fischer began setting up gear for an upcoming Japanese plant experiment.

Related links:

Expedition 52: https://www.nasa.gov/mission_pages/station/expeditions/expedition52/index.html

Body fluids in space: https://www.nasa.gov/mission_pages/station/research/experiments/1257.html

Liquid and gas mixtures: https://www.nasa.gov/mission_pages/station/research/experiments/2364.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Image (mentioned), Animation (mentioned), Text, Credits: NASA/Mark Garcia.

Best regards, Orbiter.ch

Jupiter’s Great Red Spot in True Color












NASA - JUNO Mission logo.

July 27, 2017


This image of Jupiter’s iconic Great Red Spot was created by citizen scientist Björn Jónsson using data from the JunoCam imager on NASA’s Juno spacecraft.

This true-color image offers a natural color rendition of what the Great Red Spot and surrounding areas would look like to human eyes from Juno’s position. The tumultuous atmospheric zones in and around the Great Red Spot are clearly visible.

The image was taken on July 10, 2017 at 07:10 p.m. PDT (10:10 p.m. EDT), as the Juno spacecraft performed its seventh close flyby of Jupiter. At the time the image was taken, the spacecraft was about 8,648 miles (13,917 kilometers) from the tops of the clouds of the planet at a latitude of -32.6 degrees.

JunoCam's raw images are available for the public to peruse and process into image products at:

http://www.missionjuno.swri.edu/junocam     

More information about Juno is at: https://www.nasa.gov/juno and http://missionjuno.swri.edu

Image, Text, Credits: NASA/Tony Greicius/JPL-Caltech/SwRI/MSSS/Björn Jónsson

Greetings; Orbiter.ch

Galactic David and Goliath












ESA - Hubble Space Telescope logo.

27 July 2017

NGC 1512 and NGC 1510

The gravitational dance between two galaxies in our local neighbourhood has led to intriguing visual features in both as witnessed in this new NASA/ESA Hubble Space Telescope image. The tiny NGC 1510 and its colossal neighbour NGC 1512 are at the beginning of a lengthy merger, a crucial process in galaxy evolution. Despite its diminutive size, NGC 1510 has had a significant effect on NGC 1512’s structure and amount of star formation.

Galaxies come in a range of shapes and sizes, and astronomers use this fact to classify them based on their appearance. NGC 1512, the large galaxy to the left in this image, is classified as a barred spiral, named after the bar composed of stars, gas and dust slicing through its centre. The tiny NGC 1510 to the right, on the other hand, is a dwarf galaxy. Despite their very different sizes, each galaxy affects the other through gravity, causing slow changes in their appearances.

Wide-field view of NGC 1510 and NGC 1512 (ground-based view)

The bar in NGC 1512 acts as a cosmic funnel, channelling the raw materials required for star formation from the outer ring into the heart of the galaxy. This pipeline of gas and dust in NGC 1512 fuels intense star birth in the bright, blue, shimmering inner disc known as a circumnuclear starburst ring, which spans 2400 light-years.

Both the bar and the starburst ring are thought to be at least in part the result of the cosmic scuffle between the two galaxies — a merger that has been going on for 400 million years.

NGC 1512, which has been observed by Hubble in the past, is also home to a second, more serene, star-forming region in its outer ring. This ring is dotted with dozens of HII regions, where large swathes of hydrogen gas are subject to intense radiation from nearby, newly formed stars. This radiation causes the gas to glow and creates the bright knots of light seen throughout the ring.

video
Zooming onto the galaxies NGC 1512 and NGC 1510

Remarkably, NGC 1512 extends even further than we can see in this image — beyond the outer ring — displaying malformed, tendril-like spiral arms enveloping NGC 1510. These huge arms are thought to be warped by strong gravitational interactions with NGC 1510 and the accretion of material from it. But these interactions are not just affecting NGC 1512; they have also taken their toll on the smaller of the pair.

The constant tidal tugging from its neighbour has swirled up the gas and dust in NGC 1510 and kick-started star formation that is even more intense than in NGC 1512. This causes the galaxy to glow with the blue hue that is indicative of hot new stars.

video
Pan across NGC 1512 and NGC 1510

NGC 1510 is not the only galaxy to have experienced the massive gravitational tidal forces of NGC 1512. Observations made in 2015 showed that the outer regions of the spiral arms of NGC 1512 were indeed once part of a separate, older galaxy. This galaxy was ripped apart and absorbed by NGC 1512, just as it is doing now to NGC 1510.

Hubble Space Telescope (HST)

Together, the pair demonstrate how interactions between galaxies, even if they are of very different sizes, can have a significant influence on their structures, changing the dynamics of their constituent gas and dust and even triggering starbursts. Such interactions between galaxies, and galaxy mergers in particular, play a key role in galactic evolution.

More information:

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Links:

Images of Hubble: http://www.spacetelescope.org/images/archive/category/spacecraft/

Press release on NGC 1512 (2001): https://www.spacetelescope.org/news/heic0106/

Image, Animation, Text,  Credits: ESA & NASA/Digitized Sky Survey 2/Acknowledgement: Davide De Martin/Videos: ESA/Hubble, Digitized Sky Survey, Nick Risinger (skysurvey.org)/Music: Johan B Monell.


Best regards, Orbiter.ch

A Tale of Three Stellar Cities












ESO - European Southern Observatory logo.

27 July 2017

The Orion Nebula and cluster from the VLT Survey Telescope

Using new observations from ESO’s VLT Survey Telescope, astronomers have discovered three different populations of young stars within the Orion Nebula Cluster. This unexpected discovery adds very valuable new insights for the understanding of how such clusters form. It suggests that star formation might proceed in bursts, where each burst occurs on a much faster time-scale than previously thought.

OmegaCAM — the wide-field optical camera on ESO’s VLT Survey Telescope (VST) — has captured the spectacular Orion Nebula and its associated cluster of young stars in great detail, producing a beautiful new image. This object is one of the closest stellar nurseries for both low and high-mass stars, at a distance of about 1350 light-years [1].

The jewel in Orion’s sword

But this is more than just a pretty picture. A team led by ESO astronomer Giacomo Beccari has used these data of unparallelled quality to precisely measure the brightness and colours of all the stars in the Orion Nebula Cluster. These measurements allowed the astronomers to determine the mass and ages of the stars. To their surprise, the data revealed three different sequences of potentially different ages.

“Looking at the data for the first time was one of those ‘Wow!’ moments that happen only once or twice in an astronomer's lifetime,” says Beccari, lead ­author of the paper presenting the results. “The incredible quality of the OmegaCAM images revealed without any doubt that we were seeing three distinct populations of stars in the central parts of Orion.”

The Orion Nebula showing three populations of young stars

Monika Petr-Gotzens, co-author and also based at ESO Garching, continues, “This is an important result. What we are witnessing is that the stars of a cluster at the beginning of their lives didn’t form altogether simultaneously. This may mean that our understanding of how stars form in clusters needs to be modified.”

The astronomers looked carefully at the possibility that instead of indicating different ages, the different brightnesses and colours of some of the stars were due to hidden companion stars, which would make the stars appear brighter and redder than they really were. But this idea would imply quite unusual properties of the pairs, which have never before been observed. Other measurements of the stars, such as their rotation speeds and spectra, also indicated that they must have different ages [2].

video
Zooming in on the Orion Nebula

“Although we cannot yet formally disprove the possibility that these stars are binaries, it seems much more natural to accept that what we see are three generations of stars that formed in succession, within less than three million years,” concludes Beccari.

The new results strongly suggest that star formation in the Orion Nebula Cluster is proceeding in bursts, and more quickly than had been previously thought.

video
Panning across the Orion Nebula

Notes:

[1] The Orion Nebula has been studied by many of ESO’s telescopes, including images in visible light from the MPG/ESO 2.2-metre telescope (eso1103) and infrared images from VISTA (eso1701) and the HAWK-I instrument on the Very Large Telescope (eso1625).

eso1103: http://www.eso.org/public/news/eso1103/
eso1701: http://www.eso.org/public/news/eso1701/
eso1625: http://www.eso.org/public/news/eso1625/

[2] The group also found that each of the three different generations rotate at different speeds — the youngest stars rotate the fastest, and the oldest stars rotate the slowest. In this scenario, the stars would have formed in quick succession, within a time frame of three million years.

More information:

This research was presented in a paper entitled “A Tale of Three Cities: OmegaCAM discovers multiple sequences in the color­ magnitude diagram of the Orion Nebula Cluster,” by G. Beccari and colleagues, to appear in the journal Astronomy & Astrophysics.

The team is composed of G. Beccari, M.G. Petr-Gotzens and H.M.J. Boffin (ESO, Garching bei München, Germany), M. Romaniello (ESO; Excellence Cluster Universe, Garching bei München, Germany), D. Fedele (INAF-Osservatorio Astrofisico di Arcetri, Firenze, Italy), G. Carraro (Dipartimento di Fisica e Astronomia Galileo Galilei, Padova, Italy), G. De Marchi (Science Support Office, European Space Research and Technology Centre (ESA/ESTEC), The Netherlands), W.J. de Wit (ESO, Santiago, Chile), J.E. Drew (School of Physics, University of Hertfordshire, UK), V.M. Kalari (Departamento de Astronomía, Universidad de Chile, Santiago, Chile), C.F. Manara (ESA/ESTEC), E.L. Martin (Centro de Astrobiologia (CSIC-INTA), Madrid, Spain), S. Mieske (ESO, Chile), N. Panagia (Space Telescope Science Institute, USA); L. Testi (ESO, Garching); J.S. Vink (Armagh Observatory, UK); J.R. Walsh (ESO, Garching); and N.J. Wright (School of Physics, University of Hertfordshire; Astrophysics Group, Keele University, UK).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.

Links:

Research paper: https://www.eso.org/public/archives/releases/sciencepapers/eso1723/eso1723a.pdf

Photos of the VLT Survey Telescope: http://www.eso.org/public/images/archive/search/?adv=&subject_name=VLT%20Survey%20Telescope

ESOcast 118 Light: A Tale of Three Stellar Cities (4K UHD): http://www.eso.org/public/videos/eso1723a/

ESO's Very Large Telescope (VLT): http://www.eso.org/public/teles-instr/paranal-observatory/vlt/

Images, Text, Credits: ESO/Richard Hook/Giacomo Beccari/IAU and Sky & Telescope/Videos: ESO, N. Risinger (skysurvey.org), Digitized Sky Survey 2. Music: Johan B. Monell (www.johanmonell.com).

Best regards, Orbiter.ch

mercredi 26 juillet 2017

Two Days and Counting After Crew Rocket Rolls Out to Pad













ISS - Expedition 52 Mission patch / ROSCOSMOS - Soyuz MS-05 Mission patch.

July 26, 2017

International Space Station (ISS). Animation Credits: NASA

The Soyuz MS-05 spacecraft that will launch three new crew members to the International Space Station has rolled out to its launch pad in Kazakhstan. The rocket was carted slowly by train from its processing facility to the pad and vertically raised to its launch position at the Baikonur Cosmodrome.


Image above: The Soyuz MS-05 rocket is vertically raised into launch position two days before its scheduled launch from Kazakhstan to the International Space Station. Image Credits: NASA/Joel Kowsky.

Cosmonaut Sergey Ryazanskiy will command the Soyuz when it launches Friday at 11:41 a.m. EDT. He will be flanked by flight engineers Randy Bresnik from NASA and Paolo Nespoli from the European Space Agency. The trio will take a six-hour, 19-minute ride from Earth to the station’s Rassvet module. NASA TV will broadcast the launch and docking activities live beginning at 10:45 a.m.


Image above: The Soyuz MS-05 spacecraft is seen as it is raised into a vertical position on the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, July 26, 2017. Expedition 52 flight engineer Sergei Ryazanskiy of Roscosmos, flight engineer Randy Bresnik of NASA, and flight engineer Paolo Nespoli of ESA (European Space Agency), are scheduled to launch to the International Space Station aboard the Soyuz spacecraft from the Baikonur Cosmodrome on Friday, July 28, at 11:41 a.m. EDT (9:41 p.m. Baikonur time. Photo Credit: (NASA/Joel Kowsky.

The three Expedition 52 crew members living on the space station now are moving right along with ongoing human research. Veteran astronaut Peggy Whitson continued exploring therapies that target only cancer cells. Flight Engineer Jack Fischer swabbed his mouth and body for a study tracking microbes in space. Station Commander Fyodor Yurchikhin worked life support maintenance and sampled the station’s air for a quality check.

video
Expedition 52 Soyuz Rollout (Soyuz MS-05). Video Credit: Roscosmos

Related links:

Cancer cells: https://www.nasa.gov/mission_pages/station/research/experiments/2347.html

Microbes in space: https://www.nasa.gov/mission_pages/station/research/experiments/1920.html

NASA TV coverage: https://www.nasa.gov/press-release/nasa-television-coverage-set-for-next-international-space-station-crew-launch-0

Soyuz MS-05 spacecraft pictures: https://www.flickr.com/photos/nasahqphoto/albums/72157685840653276

Expedition 52: https://www.nasa.gov/mission_pages/station/expeditions/expedition52/index.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Animation (mentioned), Images (mentioned), Video (mentioned), Text, Credits: NASA/Mark Garcia.

Best regards, Orbiter.ch

The Dark Side of the Crater: How Light Looks Different on the Moon and What NASA Is Doing About It











NASA logo.

July 26, 2017

Things look different on the Moon. Literally.


Image above: Scientists Build Sandbox to Simulate Lighting Conditions on the Moon. Image Credits: NASA/Ames Research Center.

Because the Moon isn't big enough to hold a significant atmosphere, there is no air and there are no particles in the air to reflect and scatter sunlight. On Earth, shadows in otherwise bright environments are dimly lit with indirect light from these tiny reflections. That lighting provides enough detail that we get an idea of shapes, holes and other features that could be obstacles to someone – or some robot – trying to maneuver in shadow.

"What you get on the Moon are dark shadows and very bright regions that are directly illuminated by the Sun – the Italian painters in the Baroque period called it chiaroscuro – alternating light and dark," said Uland Wong, a computer scientist at NASA's Ames Research Center in Silicon Valley. "It's very difficult to be able to perceive anything for a robot or even a human that needs to analyze these visuals, because cameras don't have the sensitivity to be able to see the details that you need to detect a rock or a crater."

In addition, the dust itself covering the Moon is otherworldly. The way light reflects on the jagged shape of individual grains, along with the uniformity of color, means it looks different if it's lit from different directions. It loses texture at different lighting angles.

Some of these visual challenges are evident in Apollo mission surface images, but the early lunar missions mostly waited until lunar “afternoon” so astronauts could safely explore the surface in well-lit conditions.

Future lunar rovers may target unexplored polar regions of the Moon to drill for water ice and other volatiles that are essential, but heavy, to take on human exploration missions. At the Moon’s poles, the Sun is always near the horizon and long shadows hide many potential dangers in terrain like rocks and craters. Pure darkness is a challenge for robots that need to use visual sensors to safely explore the surface.

Wong and his team in Ames' Intelligent Robotics Group are tackling this by gathering real data from simulated lunar soil and lighting. 

"We're building these analog environments here and lighting them like they would look on the Moon with solar simulators, in order to create these sorts of appearance conditions," said Wong. "We use a lot of 3-dimensional imaging techniques, and use sensors to create algorithms, which will both help the robot safeguard itself in these environments, and let us train people to interpret it correctly and command a robot where to go."


Image above: Above is a set from over 2,500 pairs of stereo camera images taken from at least 12 scenarios of recreated craters and rock formations that Wong and his team collected to accurately simulate the lighting conditions at the Moon's poles. The goal is to improve the stereo viewing capabilities of robotic systems to effectively navigate unknown terrain and avoid hazards at the Moon poles. Image Credits: NASA/Uland Wong.

The team uses a 'Lunar Lab' testbed at Ames – a 12-foot-square sandbox containing eight tons of JSC-1A, a human-made lunar soil simulant. Craters, surface ripples and obstacles are shaped with hand tools, and rocks are added to the terrain in order to simulate boulder fields or specific obstacles. Then they dust the terrain and rocks with an added layer of simulant to produce the “fluffy” top layer of lunar soil, erasing shovel and brush marks, and spreading a thin layer on the faces of rocks. Each terrain design in the testbed is generated by statistics based on common features observed from spacecraft around the Moon.

Solar simulator lights are set up around the terrain to create Moon-accurate low-angle, high-contrast illumination. Two cameras, called a stereo imaging pair, mimic how human eyes are set apart to help us perceive depth. The team captured photographs of multiple testbed setups and lighting angles to create a dataset to inform future rover navigation.

"But you can only shovel so much dirt; we are also using physics-based rendering, and are trying to photo-realistically recreate the illumination in these environments," said Wong. "This allows us to use a supercomputer to render a bunch of images using models that we have decent confidence in, and this gets us a lot more information than we would taking pictures in a lab with three people, for example."

The result, a Polar Optical Lunar Analog Reconstruction or POLAR dataset, provides standard information for rover designers and programmers to develop algorithms and set up sensors to safely navigate. The POLAR dataset is applicable not only to our Moon, but to many types of planetary surfaces on airless bodies, including Mercury, asteroids, and regolith-covered moons like Mars' Phobos.

So far, early results show that stereo imaging is promising for use on rovers that will explore the lunar poles.

"One of the mission concepts that's in development right now, Resource Prospector, that I have the privilege of working on, might be the first mission to land a robot and navigate in the polar regions of the Moon," said Wong. "And in order to do that, we have to figure out how to navigate where nobody's ever been."

This research is funded by the agency’s Advanced Exploration Systems and Game Changing Development programs. NASA’s Solar System Exploration Research Virtual Institute provides the laboratory facilities and operational support.

video
Scientists Build Sandbox to Simulate Lighting Conditions on the Moon

Related link:

Resource Prospector: https://www.nasa.gov/resource-prospector

For more information about NASA technology for future exploration missions, visit: https://www.nasa.gov/technology

Images (mentioned), Video, Text, Credits: NASA/Kimberly Williams/Ames Research Center/Kimberly Minafra.

Greetings, Orbiter.ch

Galileo arrives on the Space Station















ESA - Galileo Programme logo / ISS - International Space Station patch.

26 July 2017

If one’s good, two are better, and this is especially true when it comes to developing new applications for navsat systems like Galileo and GPS. That’s why an experiment on the International Space Station will start receiving signals from both simultaneously.

Satellites of America’s GPS provide signals for navigation and timing services in an enormous variety of applications worldwide – on smartphones, in automobile navigation systems and in economically vital services like aviation, maritime traffic and banking.

SCaN Testbed on Station

Today, GPS is synonymous with satnav, but after years of development and regular launches, Europe’s Galileo navigation system has come of age: its 18 satellites – soon to be 24 plus in-orbit spares – are now transmitting the highly accurate signals necessary to deliver navigation services across a wide range of activities.

“This means both European Galileo and American GPS signals can be received simultaneously, allowing us to investigate how the two sets of signals could be used together in a single device or application to provide mutually enhanced navigation,” says Werner Enderle, Head of ESA’s Navigation Support Office.

ISS - International Space Station

To achieve this two-for-one reception, a cutting-edge experiment conducted by ESA and NASA on the International Space Station will use special techniques to receive signals from both GPS and Galileo satellites.

“The aim is to generate data that can be used to demonstrate the value of a dual receiver compared to one that receives just GPS or Galileo alone,” says Werner.

“In future, this could open the door to a large range of new applications featuring the space-based use of multiple navigation satellite system signals.”

video
March 20, 2012 Space Station Briefing: SCAN Testbed Installation

SCaNing for accuracy

The experiment got underway with initial testing last year using NASA’s Space Communications and Navigation (SCaN) Testbed, an experimental software-configurable radio receiver that was installed on the Station in 2012.

The device’s capability to receive both GPS and Galileo signals had already been proven in 2014, opening the door for the use of Galileo, which uses the same frequencies and is interoperable with GPS.

Now the in-orbit experiments will make it among the world’s first space-validated, dual GPS-Galileo receivers.

This year, both agencies will continue developing the ground systems needed to support the experiment, and the main test phase is set to run from mid-2017 to the end of 2018.

Galileo satellite

“Dual Galileo–GPS signal reception in space allows us to study ways to enhance interoperability, while using the signals to achieve more precise and robust orbital predictions,” says David Chelmins, SCaN Testbed project manager at NASA’s Glenn Research Center, Cleveland, USA.

“This could lead to improved applications such as autonomous spacecraft operations and scientific measurements, and perhaps new scientific or commercial space applications no one’s even thought of yet.”

ESA teams take part

The Navigation Support Office, at ESA’s mission control centre in Darmstadt, Germany, will provide processing and analysis expertise eventually to perform a precise orbit determination to pin down the trajectory of the SCaN Testbed receiver on the Station to within tens of centimetres.

The development of the software needed to track GPS and Galileo signals simultaneously for the SCaN Testbed has been led by experts on the Radio Navigation Systems and Technology team at the Agency’s technical centre in the Netherlands.

Navigation Support Facility

This specialised software, developed in collaboration with Italian company Qascom, will convert the received Galileo and GPS signals into ‘observables’, numbers with a physical meaning from which the receiver position can be precisely calculated in space and on ground.

It is also planned that the software will generate realtime position solutions, demonstrating the ability of the Station to track its own orbit accurately and paving the way for new operational techniques.

Supporting navigation

ESA experts are well used to conducting the type of ultraprecise analysis that the SCaN experiment will require.

The Navigation Support Office routinely provides highly accurate navigation and satellite geodesy services to customers worldwide. It receives data from a wide variety of sources and then calculates and predicts highly accurate orbits, timing corrections and related products for satellites that are part of global navigation systems, like GPS, Galileo, Glonass and BeiDou.

These are used to improve global navigation satellite position accuracy, enabling even more sophisticated applications supporting scientific studies, large-scale climate monitoring, and tracking of long-term changes in Earth’s geology.

Related links:

Galileo navigation system: http://www.esa.int/Our_Activities/Navigation/Galileo/What_is_Galileo

EC Galileo website: http://ec.europa.eu/growth/sectors/space/galileo/index_en.htm

European GNSS Agency: http://www.gsa.europa.eu/

NASA’s Space Communications and Navigation (SCaN): https://www.nasa.gov/directorates/heo/scan/engineering/technology/txt_scantestbed.html

Navigation Support Office: http://www.esa.int/Our_Activities/Operations/gse/ESA_Navigation_Support_Office

Radio Navigation Systems and Technology: http://www.esa.int/Our_Activities/Space_Engineering_Technology/RF_Systems_Payloads_and_Technology

Qascom: http://www.qascom.com/

Glonass: http://www.navipedia.net/index.php/GLONASS_General_Introduction

BeiDou: http://www.navipedia.net/index.php/BeiDou_General_Introduction

ESA/Pierre Carril/J. Mai/NASA.

Greetings, Orbiter.ch