3/18/2024 0 Comments Nasa's definition of duskConsider a notional platform in a Sun-synchronous orbit (nominally 600–800 km) capable of hosting 20 or more instruments andġ “The Use of On-Orbit Assembly Platforms.-The Committee on Appropriations notes interest from industry in partnering with NASA, to support the development and demonstration of a prototype on-orbit robotically assembled Earth Science Platform designed to address critical gaps in NASA’s climate, weather, and ecosystem monitoring.1 To assist in their preparation of the requested analysis, NASA requested the National Academies’ CESAS conduct a short study that would assess the potential use of a proposed multi-user, robot-tended, uncrewed commercial space platform as a potential host for a large number of Earth remote sensing instruments. Senate contain language directing NASA to study the feasibility and practicality of partnering with industry to develop a space-based platform using multiple modular Earth remote sensing instruments to conduct Earth science observations. So if we always want to be over something with nice bright midday Sun then we’ll make sure we always see that with the Sun-synchronous orbit.Robotically Assembled Earth Science Platform.-NASA is encouraged to support, in partnership with industry, the development and deployment of capabilities using NASA-supported robotic assembly and on-orbit structure manufacturing technologies to enable operation of multiple modular Earth remote sensing instruments.Ĭommittee reports accompanying FY 2023 appropriations bills from both the U.S. And that can be quite useful for observation and scientific missions where we want to get consistent lighting conditions on the ground. With the Sun-synchronous orbit, we’re locked to the Sun essentially, and so if we start out seeing noon and midnight, we’ll always see noon and midnight. If we weren’t in a Sun-synchronous orbit, then we might start out seeing noon and midnight and then later in the year we’d be seeing some other time of day, and it would change over time. If we pick the right altitude and the right inclination relative to the equator, we can actually get a precession rate at which that orbit changes that just happens to exactly match the rate at which the Earth goes around the Sun.Īnd what that means is that, if we put a spacecraft into an orbit where, when it initially takes off and is flying around the Earth, it spends part of its time directly over a point that’s seeing midday Sun and the other half of its orbit over the side of the Earth where it’s exactly at midnight, we’re going to maintain that all the way through the year, because as the Earth moves around the Sun, the orbit’s also shifting. But with a Sun-synchronous orbit, what we actually try to do is take advantage of that. Normally that’s something that we either ignore or counter the effects of by manoeuvring the spacecraft. So you’re not just orbiting around the Earth – the circle of the orbit is actually shifting in space as well. And in the case of the shape of the Earth, one of the changes that we see with orbits is something called precession of the orbit, and precession basically means that the orbit moves relative to the Earth over time. So orbits are not fixed in space, they tend to change over time, and one of the things that makes an orbit change is the shape of the Earth. Wow, this is where we get into the complexities or orbit mechanics. Sun-synchronous orbit is a special kind of orbit. Satellite examples: Landsat 7, CloudSat Transcript Dr Allan McInnes It is a low-Earth orbit.Īdvantage: consistent lighting conditions of the Earth’s surface enable us to compare images from the same season over several years A Sun-synchronous orbit matches the rate at which the Earth goes around the Sun.
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