RADARSAT Constellation

<P><p><div><p><b>RADARSAT Constellation</b></p></P><P><img src="https://img.yfisher.com/1631236352424.jpg" style="margin:10px auto"></P><P><p>The RADARSAT Constellation Mission (RCM) is a three-spacecraft fleet of Earth observation satellites operated by the Canadian Space Agency. The RCM's goal is to provide data for climate research and commercial applications including oil exploration, fishing, shipping, etc. With satellites smaller than RADARSAT-2, the RCM will provide new applications-made possible through the constellation approach-as well as continuing to provide C-band radar data to RADARSAT-2 users. One of its most significant improvements is in its operational use of synthetic-aperture radar (SAR) data. The primary goal of RCM is to provide continuous C-band SAR data to RADARSAT-2 users, as SAR imagery at a high temporal resolution is required by several users in the Canadian government. Other improvements include more frequent area coverage of Canada and reduced risk of a service interruption. The three satellites were launched on 12 June 2019 at 14:17 UTC on board a Falcon 9 rocket. Originally booster B1050 was planned to be used for this mission. However, after the failed landing of B1050, B1051 was used in this mission.</p><p>------</p><p><b>Grus (constellation)</b></p><p>Grus (/rs/, or colloquially /rus/) is <a href="https://www.meetujewelry.com/a-radarsat-constellation.html">a constellation</a> in the southern sky. Its name is Latin for the crane, a type of bird. It is one of twelve constellations conceived by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Grus first appeared on a 35-centimetre-diameter (14-inch) celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayer's star atlas Uranometria of 1603. French explorer and astronomer Nicolas-Louis de Lacaille gave Bayer designations to its stars in 1756, some of which had been previously considered part of the neighbouring constellation Piscis Austrinus. The constellations Grus, Pavo, Phoenix and Tucana are collectively known as the "Southern Birds". The constellation's brightest star, Alpha Gruis, is also known as Alnair and appears as a 1.7-magnitude blue-white star. Beta Gruis is a red giant variable star with a minimum magnitude of 2.3 and a maximum magnitude of 2.0. Six star systems have been found to have planets: the red dwarf Gliese 832 is one of the closest stars to Earth to have a planetary system. Another-WASP-95-has a planet that orbits every two days. Deep-sky objects found in Grus include the planetary nebula IC 5148, also known as the Spare Tyre Nebula, and a group of four interacting galaxies known as the Grus Quartet.</p></P><P><img src="https://img.yfisher.com/1643077836652.jpg" style="margin:10px auto"></P><P><p>------</p><p><b>Constellation Theatre Company</b></p><p>Constellation Theatre Company is a non-profit theater company located in Washington, D.C. It performs at Source, a flexible black box theatre in Washington, D.C. Since its founding in 2007, Constellation has received several Helen Hayes Awards including The John Aniello Award for Outstanding Emerging Theatre Company in 2009.</p><p>------</p><p><b>Original Iridium constellation</b></p><p>The satellites each contained seven Motorola/Freescale PowerPC 603E processors running at roughly 200 MHz, connected by a custom backplane network. One processor was dedicated to each cross-link antenna ("HVARC"), and two processors ("SVARC"s) are dedicated to satellite control, one being a spare. Late in the project an extra processor ("SAC") was added to perform resource management and phone call processing. The cellular look down antenna had 48 spot beams arranged as 16 beams in three sectors. The four inter-satellite cross links on each satellite operated at 10 Mbit/s. Optical links could have supported a much greater bandwidth and a more aggressive growth path, but microwave cross links were chosen because their bandwidth was more than sufficient for the desired system.</p><p>Nevertheless, a parallel optical cross link option was carried through a critical design review, and ended when the microwave cross links were shown to support the size, weight and power requirements allocated within the individual satellite's budget. Iridium Satellite LLC stated that their second generation satellites would also use microwave, not optical, inter-satellite communications links. Iridium's cross-links are unique in the satellite telephone industry as other providers do not relay data between satellites; Globalstar and Inmarsat both use a transponder without cross-links. The original design as envisioned in the 1960s was that of a completely static "dumb satellite" with a set of control messages and time-triggers for an entire orbit that would be uploaded as the satellite passed over the poles. It was found that this design did not have enough bandwidth in the space-based backhaul to upload each satellite quickly and reliably over the poles. Moreover, fixed, static scheduling would have left more than 90% of the satellite links idle at all times.</p><p>Therefore, the design was scrapped in favour of a design that performed dynamic control of routing and channel selection late in the project, resulting in a one-year delay in system delivery. Each satellite can support up to 1100 concurrent phone calls at 2400 bit/s and weighs about 680 kilograms (1,500 lb). The Iridium System presently operates within a 1618.85 to 1626.5 MHz band, part of the wider L band, adjacent to the 1610.6-1613.8 MHz Radio Astronomy Service (RAS) band. The configuration of the Satellite concept was designated as Triangular Fixed, 80 Inch Main Mission Antenna, Light-weight (TF80L). The packaging design of the spacecraft was managed by Lockheed Bus Spacecraft team; it was the first commercial satellite bus designed at the Sunnyvale Space Systems Division in California. The TF80L configuration was considered a non-conventional, innovative approach to developing a satellite design that could be assembled and tested in five days. The TF80L design configuration was also instrumental in simultaneously solving fundamental design problems involving optimization of the communications payload thermal environment and RF main mission antenna performance, while achieving the highest payload fairing packaging for each of the three main launch vehicle providers.</p><p>The first spacecraft mock-up of this design was built in the garage workshop in Santa Clara, California for the Bus PDR/CDR as a proof-of-concept model. This first prototype paved the way for the design and construction of the first engineering models. This design was the basis of the largest constellation of satellites deployed in low Earth orbit. After ten years of successful on-orbit performance, the Iridium team celebrated the equivalent of 1,000 cumulative years of on-orbit performance in 2008. One of the engineering Iridium satellite models was placed on permanent exhibit in the National Air and Space Museum in Washington, D.C. Launch campaign95 of the 99 built satellites were launched between 1997 and 2002.[clarification needed] Four satellites were kept on the ground as spares. The 95 satellites were launched over twenty-two missions (nine missions in 1997, ten in 1998, one in 1999 and two in 2002). ^ Iridium satellite number changed over time following failure and replacement.</p><p>In-orbit sparesSpare satellites are usually held in a 666 kilometres (414 mi) storage orbit. These can be boosted to the correct altitude and put into service in case of a satellite failure. After the Iridium company emerged from bankruptcy the new owners decided to launch seven new spares, which would have ensured two spare satellites were available in each plane. As of 2009[update], not every plane had a spare satellite; however, the satellites can be moved to a different plane if required. A move can take several weeks and consumes fuel which will shorten the satellite's expected service life.</p><p>Significant orbital inclination changes are normally very fuel-intensive, but orbital perturbation analysis aids the process. The Earth's equatorial bulge causes the orbital right ascension of the ascending node (RAAN) to precess at a rate that depends mainly on the period and inclination. A spare Iridium satellite in the lower storage orbit has a shorter period so its RAAN moves westward more quickly than the satellites in the standard orbit. Iridium simply waits until the desired RAAN (i.e., the desired orbital plane) is reached and then raises the spare satellite to the standard altitude, fixing its orbital plane with respect to the constellation. Although this saves substantial amounts of fuel, it can be a time-consuming process.</p><p>As of mid-2016, Iridium has experienced in-orbit failures which cannot be corrected with in-orbit spare satellites, thus only 64 of the 66 satellites required for seamless global coverage were in operation. Therefore, service interruptions can be observed, especially around the equatorial region where the satellite footprints are most spread out and there is least overlap.</p></div></p></P>