Image of the week: This Landsat image features the Clearwater Lakes in Canada’s Quebec province

This Landsat image from 9 September 2010 features the Clearwater Lakes in Canada’s Quebec province. Located to the east of the Hudson Bay, what appears to be two separate lakes is actually a single body of water that fills two depressions. The depressions were created by two meteorite impacts, believed to have hit Earth simultaneously up to 290 million years ago. The name 'Clearwater Lakes' comes from the clarity of its water.

ESA supports the Landsat series as a Third Party Mission, meaning it uses its ground infrastructure and expertise to acquire, process and distribute Landsat data to users.

This image is featured on the Earth from Space video programme.

This Landsat image from 9 September 2010 features the Clearwater Lakes in Canada’s Quebec province.

Located to the east of the Hudson Bay, what appears to be two separate lakes is actually a single body of water that fills two depressions. The depressions were created by two meteorite impacts, believed to have hit Earth simultaneously up to 290 million years ago.

The larger of the two to the northwest is about 36 km in diameter and has a ring of islands in the centre. The smaller is about 26 km in diameter. A string of islands separate the two water-filled craters.

The name 'Clearwater Lakes' comes from the clarity of its water.

The surrounding terrain is dotted with smaller lakes and rivers. The topography of this area, known as the Canadian Shield, was shaped by the huge ice sheets and glaciers from the last ice ages covering the area up to 15 000 years ago.

The Thematic Mapper on Landsat-5 is jointly managed by NASA and the US Geological Survey. ESA supports the Landsat series as a Third Party Mission, meaning it uses its ground infrastructure and expertise to acquire, process and distribute Landsat data to users.

This image is featured on the Earth from Space video programme.

ESA

Guillermo Gonzalo Sánchez Achutegui

ayabaca@gmail.com

ayabaca@hotmail.com

ayabaca@yahoo.com

ESA - International effort helps users get ready for Sentinel-1

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Vancouver harbour, Canada

 This radar image of Vancouver harbour was acquired by Canada’s Radarsat-2. Owned and operated by McDonald, Dettwiler and Associates, Radarsat-2 was carefully reprogrammed to match the way Europe’s upcoming Sentinel-1satellite will image Earth and show the quality of images that can be expected.-
Those who need satellite data for a wide range of applications, from mapping sea ice and tracking maritime traffic to monitoring geohazards over land, are eagerly awaiting the launch of Sentinel-1. ESA is helping users get ahead of the game by offering test data and simulated images.

To be launched later this year, Sentinel-1 is the first of five satellite missions dedicated to supplying a stream of data for Europe’s Global Monitoring for Environment and Security ‘Copernicus’ programme. 
This particular satellite will provide timely high-quality radar images of our planet’s surface to support European operational services that use Earth observation data in areas such as emergency response, marine and land monitoring, civil security and climate studies.

Sentinel-1

Getting ready for using Sentinel data is a complex task. The new data format and information structure, the increased data volume, the expected data quality and sensor characteristics all mean that users have to develop or update processing facilities before the launch.
An important step forward in this respect is the availability of simulated products and documentation to users. ESA is responding to these needs in two ways.
Firstly, ESA has just released a sample of Sentinel-1 simulated user products and associated format and product definition documents to GMES users. In addition, the Agency is planning a further distribution to all potential users in the coming weeks.

Simulated Sentinel-1 data

This first release contains a set of simulated radar intensity ‘Level-1’ products, covering all four Sentinel-1 imaging modes and different product types. An example is shown by way of the image of the Netherlands on the right.
Notably, these products were generated by a preliminary version of Sentinel-1’s operational Instrument Processing Facility.
Though they are not intended to reflect the final characteristics of the user products, the format and contents are representative of what the mission will offer.
This will evolve with new versions of the facility and may be slightly tuned following system qualification and inflight commissioning.

Joel Dorandeu from MyOcean said, “We very much welcome the efforts being made to help service providers such as us prepare for the new data from Sentinel-1.
“Considering the volumes of data we expect from Sentinel-1 along with its method of acquisition we have the challenge of developing new processing chains.
“We are now eager to start simulating our products."
To complement this initial release of test data, ESA is, in parallel, simulating Sentinel-1 acquisitions from space using Canada’s Radarsat-2 satellite.

Vancouver radar image

This initiative is now starting to bear fruit following the first full simulation of a Sentinel-1 radar image as shown in picture at the top and here on the left.
Thanks to its owner and operator, McDonald, Dettwiler and Associates, Radarsat-2 was carefully reprogrammed to match the way Sentinel-1 will be operated. A remarkable achievement is the fact that Radarsat was able to emulate the way Sentinel-1 images Earth’s surface using a method called TOPS, thus providing a quality of image almost exactly the same as Sentinel-1.

The very first results are promising, as can be seen in the images acquired over Vancouver harbour on the west coast of Canada. The city is clearly visible, as are the ships docked in the harbour, the coastline and the nearby mountain ranges.
The acquisition of more images over specific test sites are planned to demonstrate the suitability of Sentinel-1 for classifying sea-ice, for applications using ocean winds and waves, and for detecting ships, thereby preparing users for the uptake of data.
Dedicated acquisitions of image pairs and data stacks suitable for measuring surface movements such as glacier dynamics and subsidence are also planned to take place in the coming months.
As for the current set of test data, the Radarsat-2 simulated images will also be processed and formatted using the Sentinel-1 Instrument Processing Facility and made available to users shortly.

Sentinel-1

The Sentinel-1 mission is a polar-orbiting satellite system for the continuation of Synthetic Aperture Radar (SAR) operational applications.
Sentinel-1 is a C-band imaging radar mission to provide an all-weather day-and-night supply of imagery for GMES user services. The first Sentinel-1 satellite is envisaged to launch in 2013 and will be followed by the second satellite a few years later.
Dedicated to GMES, Sentinel-1 will ensure the continuity of C-band SAR data, building on ESA’s and Canada’s heritage SAR systems on ERS-1, ERS-2, Envisat and Radarsat.
The SAR sensor will operate in two main modes: Interferometric Wide Swath and Wave. The first has a swath width of 250 km and a ground resolution of 5×20 m. These two modes will satisfy most of the envisaged service requirements. Two other mutually exclusive modes are provided for continuity with other SAR missions and to accommodate emerging user requirements.
Sentinel-1's revisit time, geographical coverage and rapid data dissemination are key to providing essential data for GMES. The Sentinel-1 pair is expected to provide coverage over Europe, Canada and main shipping routes in 1–3 days, regardless of weather conditions. Radar data will be delivered within an hour of acquisition – a big improvement over existing SAR systems.

Sentinel-1 will aid sea-ice monitoring

The mission will benefit numerous services. For example, services that relate to the monitoring of Arctic sea-ice extent, routine sea-ice mapping, surveillance of the marine environment, including oil-spill monitoring and ship detection for maritime security, monitoring land-surface for motion risks, mapping for forest, water and soil management and mapping to support humanitarian aid and crisis situations.
The design of the Sentinel-1 mission with its focus on reliability, operational stability, global coverage, consistent operations and quick data delivery is expected to enable the development of new applications and meet the evolving needs of GMES.

Sentinel-1 is being realised by an industrial consortium led by Thales Alenia Space Italy as Prime Contractor, with Astrium Germany responsible for the C-SAR payload incorporating the central radar electronics subsystem developed by Astrium UK.
Sentinel-1 will be launched on a Soyuz rocket from Europe's Spaceport in French Guiana.

ESA

Guillermo Gonzalo Sánchez Achutegui

ayabaca@gmail.com

ayabaca@hotmail.com

ayabaca@yahoo.com

Astronomy: NASA Scientists Find History of Asteroid Impacts in Earth Rocks

Hi My Friends: A VUELO DE UN QUINDE EL BLOG., Research by NASA and international scientists concludes giant asteroids, similar or larger than the one believed to have killed the dinosaurs, hit Earth billions of years ago with more frequency than previously thought.

NASA Scientists Find History of Asteroid Impacts in Earth Rocks :

WASHINGTON -- Research by NASA and international scientists concludes giant asteroids, similar or larger than the one believed to have killed the dinosaurs, hit Earth billions of years ago with more frequency than previously thought.

To cause the dinosaur extinction, the killer asteroid that impacted Earth 65 million years ago would have been almost 6 miles (10 kilometers) in diameter. By studying ancient rocks in Australia and using computer models, researchers estimate that approximately 70 asteroids the same size or larger impacted Earth 1.8 to 3.8 billion years ago. During the same period, approximately four similarly-sized objects hit the moon.

"This work demonstrates the power of combining sophisticated computer models with physical evidence from the past, further opening an important window to Earth's history," said Yvonne Pendleton, director of NASA's Lunar Science Institute (NLSI) at NASA's Ames Research Center at Moffett Field, Calif.

Evidence for these impacts on Earth comes from thin rock layers that contain debris of nearly spherical, sand-sized droplets called spherules. These millimeter-scale clues were formerly molten droplets ejected into space within the huge plumes created by mega-impacts on Earth. The hardened droplets then fell back to Earth, creating thin but widespread sedimentary layers known as spherule beds.
The new findings are published today in the journal Nature.

"The beds speak to an intense period of bombardment of Earth," said William Bottke principal investigator of the impact study team at the Southwest Research Institute (SwRI) in Boulder, Colo. "Their source long has been a mystery."

The team's findings support the theory Jupiter, Saturn, Uranus and Neptune formed in different orbits nearly 4.5 billion years ago, migrating to their current orbits about 4 billion years ago from the interplay of gravitational forces in the young solar system. This event triggered a solar system-wide bombardment of comets and asteroids called the "Late Heavy Bombardment." In the paper, the team created a model of the ancient main asteroid belt and tracked what would have happened when the orbits of the giant planets changed. They discovered the innermost portion of the belt became destabilized and could have delivered numerous big impacts to Earth and the moon over long time periods.

At least 12 mega-impacts produced spherule beds during the so-called Archean period 2.5 to 3.7 billion years ago, a formative time for life on Earth. Ancient spherule beds are rare finds, rarer than rocks of any other age. Most of the beds have been preserved amid mud deposited on the sea floor below the reach of waves.

The impact believed to have killed the dinosaurs was the only known collision over the past half-billion years that made a spherule layer as deep as those of the Archean period. The relative abundance of the beds supports the hypothesis for many giant asteroid impacts during Earth's early history.

The frequency of the impacts indicated in the computer models matches the number of spherule beds found in terrains with ages that are well understood. The data also hint at the possibility that the last impacts of the Late Heavy Bombardment on Earth made South Africa's Vredefort crater and Canada's Sudbury crater, both of which formed about 2 billion years ago.

"The Archean beds contain enough extraterrestrial material to rule out alternative sources for the spherules, such as volcanoes," said Bruce Simonson, a geologist from Oberlin College in Oberlin, Ohio.

The research was funded by NLSI and conducted by members or associates of NLSI's Center of Lunar Origin and Evolution, based at SwRI.

The impact study team also includes scientists from Purdue University in West Lafayette, Ind.; Charles University in Prague, Czech Republic; Observatorie de la Cote d'Azur in Nice, France; and Academia Sinica in Taipei, Taiwan.

To learn about the NLSI, visit:
http://lunarscience.arc.nasa.gov/

Guillermo Gonzalo Sánchez Achutegui

ayabaca@gmail.com

ayabaca@hotmail.com

ayabaca@yahoo.com