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During the earth to mars cruise and until the Skycrane lowering system was initiated Perseverance must have been attached to the SC frame and presumably released by frangible bolts...my question is: were the suspension cables stowed in Perseverance's body and then fed out via a braking system or was there a lowering system on the SC

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The skycrane fed the cables out from a spool contained in the Bridle and Umbilical Device (BUD).

As the DS maintains a constant vertical velocity of 0.75 m/s, the rover is lowered on a triple bridle to 7.5 m below the DS through the use of an electromagnetic brake connected to a spool containing the three bridles. All of the bridles pass through a confluence point on the DS which is nearly collocated with the DS center of mass. In doing so, the Rover imparts minimal disturbance on the DS. Since all three bridles pass through a single point, it is impossible for differential loading of the bridle to produce moments on the DS. Figure 15 shows the BUD.

enter image description here

....Once touchdown is declared, the DS halts vertical motion and the triple bridles are cut. The BUD has built-in retraction springs to retract the now free bridles away from the Rover top deck.

DS = Descent Stage

Source MSL Entry, Descent, and Landing Overview

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    $\begingroup$ That answers 100% of my question, well done $\endgroup$ Mar 8, 2021 at 20:47
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A lowering system was present on the SC. So the cable doesn't interfere with Perseverance. Also, you can see on Perserverence's pictures thoses cables cutted. This picture is from Curiosity but the technique was the same.

From What was the use of these cutted cables?

enter image description here click for larger

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