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 In the footage, a cosmic ray striking the camera sensor is visible, materializing as a small black artifact in the 17th frame.A Sun-synchronous orbit matches the rate at which the Earth goes around the Sun. However, due to the rover’s other activities being intentionally scaled back ahead of the conjunction, NASA used this opportunity to let the Hazcams record 12 hours of snapshots for the first time ever-in an attempt to capture clouds on Mars and “dust devils” to gain a better understanding of Mars’ weather patterns.Īdditionally, a second video captures footage from the rear Hazcam, looking northwest down the slopes of Mount Sharp. NASA further notes that Curiosity’s Hazcams are typically used for identifying rocks, slopes, and other hazards that may be dangerous for the rovers to traverse. But plasma from the Sun can interfere with radio communications, so “missions hold off on sending commands to Mars spacecraft for several weeks during this time.”ĪLSO READ: NASA Beams ‘Ultra-HD’ Cat Video From Deep Space Same Tech To Aid Manned Missions On Mars “Instructions to record the videos were part of the last set of commands beamed up to Curiosity just before the start of Mars solar conjunction, a period when the Sun is between Earth and Mars,” NASA says.
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