The Perseverance rover is set to land on Jezero crater on Mars, in February 2021.

It is clear that if you want to land in location X you need to enter the atmosphere at point Y.

From the animated entrance video that NASA released, it seems like the spacecraft will get to Mars at the correct angle at the correct time at the correct location in order to end up in the right place, without rotating first around Mars.

Will that be the real situation? Will the flight to Mars be planed to the minutes and seconds - while taking into account Mars' rotation around itself - so once reaching the planet the spacecraft will be able to immediately start the entry phase?

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    $\begingroup$ The answer is basically "yes", though perhaps someone can elaborate. There are usually some very small "mid-course corrections" during the months of flight to make sure the spacecraft does get to exactly the right place at exactly the right time. $\endgroup$ – Steve Linton Jan 10 at 15:35
  • $\begingroup$ Also note that "point X" is large, its a landing ellipse of roughly 10km diameter. Its not like they are landing exactly on the X like SpaceX does for barge and RTLS landings on earth. $\endgroup$ – Polygnome Jan 11 at 9:52
  • $\begingroup$ Also, a very good read (although for Curiosity, but Perseverance is based on it): Mars Science Laboratory Entry, Descent, and Landing System Overview $\endgroup$ – Polygnome Jan 11 at 10:01
  • $\begingroup$ Rockets and guidance systems are very precise. $\endgroup$ – dalearn Jan 11 at 17:49

NASA plans multiple translational correction maneuvers for their spacecraft headed toward another planet. The intent of these correction maneuvers is to bring the spacecraft back on track so as to reach the intended target. NASA has become very proud of the fact that the last few correction maneuvers have been waived off; the corrections in the early maneuvers have become so accurate that the last few maneuvers are not needed.

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    $\begingroup$ They also track the spacecraft via radio signals, which gives them very accurate range and doppler information that allows them to check that it's on track. The process...and a failure to follow it correctly which led to loss of the mission...is described in this article: spectrum.ieee.org/aerospace/robotic-exploration/… $\endgroup$ – Christopher James Huff Jan 10 at 22:14
  • $\begingroup$ What about rapidly changing solar wind condtions / CMEs that might occur? I imagine those could fluff up the upper atmosphere of Mars, which is responsible for the majority of aerobraking, quite significantly. In those cases some last-minute corrections would still be required, or are the early trajectories that good? $\endgroup$ – AtmosphericPrisonEscape Jan 10 at 22:33
  • $\begingroup$ @AtmosphericPrisonEscape, unless the craft were to make multiple passes through the atmosphere, the difference in entry between a low-activity sun and a very high-activity sun will be tiny. The aerobraking phase is only a few minutes long in either situation. $\endgroup$ – BowlOfRed Jan 11 at 3:13
  • $\begingroup$ @AtmosphericPrisonEscape If the re-entry is anything like Curiosity's, then the vehicle is actively steering itself during re-entry, pretty much the same way that Apollo capsules were steered: The center of mass is offset, giving the capsule an angle-of-attack and therefore lift, and then rotational thrusters are used to point the lift vector in various directions to affect the reentry trajectory. I would imagine that a thicker or thinner atmosphere should be compensated for by the active steering. $\endgroup$ – Wayne Conrad Jan 11 at 18:58

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