Landsat 7, launched on April 15, 1999, is the latest satellite of the Landsat program. Landsat 7's primary goal is to refresh the global archive of satellite photos, providing up-to-date and cloud-free images. The Landsat Program is managed and operated by the USGS, and data from Landsat 7 is collected and distributed by the USGS. The NASA World Wind project allows 3D images from Landsat 7 and other sources to be freely navigated and viewed from any angle. The satellite's companion, Earth Observing-1, trails one minute following the exact orbital characteristics.
Landsat 7 was designed to last for five years, and has the capacity to collect and transmit up to 532 images per day. It is in a polar, sun-synchronous orbit, meaning it scans across the entire earth's surface. With an altitude of 705 kilometres +/- 5 kilometres, it takes 232 orbits, or 16 days, to do so. The satellite weighs 1973 kg, is 4.04 m long, and 2.74 m in diameter. Unlike its predecessors, Landsat 7 has a solid state memory of 378 gigabits (roughly 100 images). The main instrument on board Landsat 7 is the Enhanced Thematic Mapper Plus (ETM+).
On May 31, 2003 the Scan Line Corrector (SLC) in the ETM+ instrument failed. The SLC consists of a pair of small mirrors that rotate about an axis in tandem with the motion of the main ETM+ scan mirror. The purpose of the SLC is to compensate for the forward motion (along-track) of the spacecraft so that the resulting scans are aligned parallel to each other. Without the effects of the SLC, the instrument images the Earth in a "zig-zag" fashion, resulting in some areas that are imaged twice and others that are not imaged at all. The net effect is that approximately 22% of the data in a Landsat 7 scene is missing when acquired without a functional SLC.
Landsat 7 continues to acquire data in this mode. Data products are available with the missing data optionally filled in using other Landsat 7 data selected by the user. To continue the Landsat legacy, studies are underway to fly an equivalent scientific sensor on a new satellite.
Volgograd Arena (45,000 spectators): An emotional World Cup venue. On the bank of the Volga, the new stadium was built against the backdrop of the war memorial "Mother's Homeland Calls". During construction, bones were found by soldiers of the Second World War.
Group matches: Tunisia - England (June 18); Nigeria - Iceland (22 June); Saudi Arabia - Egypt (25 June); Japan - Poland (June 28)
Mordovia Arena (45,000 spectators): On the outskirts of Saransk, the new building was launched in 2010, the 1000th anniversary of the unification of the Mordovian and Russian population. After the World Cup there will be a dismantling for tennis and volleyball fields.
Group matches: Peru - Denmark (16 June); Colombia - Japan (19 June); Iran - Portugal (25 June); Panama - Tunisia (June 28)
Samara Arena (45,000 spectators): The ambitious construction project in the forest just outside the city lagged behind the schedule for a long time.
Group matches: Costa Rica - Serbia (17 June); Denmark - Australia (21 June); Uruguay - Russia (25 June); Senegal - Colombia (June 28)
A knockout round, a quarter-finals | Source: REUTERS
Rostov on the Don-Arena (45,000 spectators): Right on the banks of the Don is the new arena. The roof of the new building should symbolize the course of the river. FK Rostov, who beat the Bavarians in the Champions League, is playing here after the World Cup.
Group matches: Brazil - Switzerland (17 June); Uruguay - Saudi Arabia (June 20); South Korea - Mexico (23 June); Iceland - Croatia (June 26th)
A knockout round | Source: REUTERS