The Perseverance rover is collecting samples of Martian rocks and soil, which will be picked up and returned to Earth on a future mission. In this comment to another question, I note that the sample return mission will need to be careful not to hit the samples and equipment already on the surface.

Such a sample return mission could be delivered by sky crane, like Curiosity and Perseverance were. A landing ellipse can be chosen that avoids existing equipment and samples. However, once the payload touches down, the sky crane is flown away and crashed.

To avoid crashing into existing equipment and samples, does the Curiosity/Perseverance skycrane already have the ability to fly away in a particular compass direction (e.g. northwest)? If not, is it just a matter of software changes, or is more hardware needed?

(The backshell and heat shield are also considerations, but I will leave that to another question.)


2 Answers 2


Yes, the skycrane was able to fly in a certain direction. Once the rover was on the surface and the bolts were cut, the skycrane was programmed to angle itself forwards or backwards, whichever way was closer to North, and fly that way. This was to ensure that the rover wouldn't be damaged by the rockets going over it.

You can hear Al Chen, the EDL lead, explain it during the landing livestream here (timestamp 42:34).


Lets have a look to the Mars landing locations:

enter image description here

Image Source Wikipedia

This map shows the full circumference of Mars, the equatorial radius is 3396.2 ± 0.1 km, so the circumference is 21,338 km. 5 degrees of the horizontal longitude scale are 295 km.

The distance between two close landing sites are at least several hundred kilometers. If a skycrane crashes some km away from its rover it is impossible to come close to any other landing site.

The aibility to fly away in a certain direction is not needed today.

This ability may be needed in the next decades when a sample return mission is planned in detail-

  • 3
    $\begingroup$ Sorry, but this does not answer the question. The premise of the question is that a new mission is intentionally landing near Perseverance, to collect its samples. In contrast, existing missions have been spread out, not only to avoid crashing into other missions, but also to diversify the scientific value. $\endgroup$
    – DrSheldon
    Mar 17, 2021 at 2:34

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