Perseverance's pyrotechnic cable cutters severed deployment lines after touchdown
the verdict
REFUTED
the evidence says no
refutedsupported
the weight of evidence
0 sources for · 2 against
AS REPORTEDno primary record reached; this is what the reporting says
Evidence shows that while pyrotechnic cable cutters were used on Perseverance, they were triggered during rover and descent stage separation rather than after touchdown as asserted.
# How were Perseverance's cables "cut" after touching down?
Tags: mars, landing, rovers, perseverance
- Score: 62
- Views: 12153
- Answers: 4
- Answered: yes
- Asked by: F16Falcon (703 rep)
- Asked: 2021-02-23
- Edited: 2021-02-23
- Site: space
## Question
In the NASA conference today regarding Perseverance's successful landing on Mars, they talked about how you can see the cable that held the rover in this picture below (I circled the cable).
I'm wondering: it looks to me like the cable was cut - if so, how did they cut it? And why would they choose to physically cut the cable rather than using some other mechanism that simply disconnects it (I'm sure they have a good reason, I'm just curious)?
## Answers
### Answer by transistor09 (score: 11 [ACCEPTED])
All cables, conductive or otherwise, were severed using pyro-cutters. These devices drive a sharp wedge through a cable using force of a small explosion.
But alas! The bundle of cables in question was actually not cut on touchdown, but during rover/descent stage separation. Cutters that were set off to confirm landing are actually still attached to the rover and will be visible in pictures!
Before landing
source: NASA/JPL-
Umbilical Deployment Device - NASA Technical Reports Server (NTRS)
## NTRS
## NTRS - NASA Technical Reports Server
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Umbilical Deployment DeviceThe landing scheme for NASA's next-generation Mars rover will encompass a novel landing technique (see figure). The rover will be lowered from a rocket-powered descent stage and then placed onto the surface while hanging from three bridles. Communication between the rover and descent stage will be maintained through an electrical umbilical cable, which will be deployed in parallel with structural bridles. The -inch (13-mm) umbilical cable contains a Kevlar rope core, around which wires are wrapped to create a cable. This cable is helically coiled between two concentric truncated cones. It is deployed by pulling one end of the cable from the cone. A retractable mechanism maintains tension on the cable after deployment. A break-tie tethers the umbilical end attached to the rover even after the cable is cut after touchdown. This break-tie allows the descent stage to develop some velocity away from
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