Winston
Lorenzo von Matterhorn
- Joined
- Jan 31, 2009
- Messages
- 9,560
- Reaction score
- 1,748
One of the improvement on Perseverance was to angle the Skycrane thrusters outward a few degrees more to avoid the dust and debris issue they had with Curiosity. Also, the two fragile wind sensors, two being needed to detect wind direction properly, one of which was killed by debris upon Curiosity's landing are retracted into a shield at landing. The Skycrane blown dust was so bad with Curiosity that it even got under hazcam dustcaps.
Curiosity [dust caps on]:
Perseverance [dust caps on]:
And how are the nylon lines which lower the rover from the Skycrane rolled out? Via a non-abrasive brake mechanism which uses an electrical generator loaded by an array of resistors! Vary the load and you vary the rate at which the lines are spooled out.
https://orise.orau.gov/resources/st...rporation-safely-landing-the-perseverance.pdf
A key component of the Skycrane landing system is the device which allows the rover to be lowered by a distance of 7.0 m to fully extend its bridle, as the cord couldn’t be extended during entry through the planets’ atmosphere. This device - the Descent Brake Mechanism - allows this deployment to happen quickly and with controlled speed that decreases toward the end of deployment for a controlled landing at the full bridle length. Composed of a main generator, resistor board, and additional parts illustrated in Figure 4, this design lets the mechanism work in a way that doesn’t provide friction against the bridle as it deploys at a constant rate to its’ max length. A lack of friction and a high degree of control over the deployment lets the minimum amount of energy be released, which came out to around 24 kJ. This design has the advantage of being completely passive, and unlike previous friction technologies, also offers highly consistent performance over a wide temperature range.
Other very interesting EDL and rover specifics in a 2018 JPL Powerpoint presentation:
https://www.colorado.edu/event/ippw..._7_stilley_presid564_presslides_docid1142.pdf
And some interesting stuff I heard on the JPL net on YouTube before they cut it off. They really don't think anyone is interested in hearing this kind of stuff?
Cruise stage: 55.91 kg propellant remaining at separation
Descent stage: 401 kg propellant loaded, 305 kg used, 96 kg remaining
Curiosity [dust caps on]:
Perseverance [dust caps on]:
And how are the nylon lines which lower the rover from the Skycrane rolled out? Via a non-abrasive brake mechanism which uses an electrical generator loaded by an array of resistors! Vary the load and you vary the rate at which the lines are spooled out.
https://orise.orau.gov/resources/st...rporation-safely-landing-the-perseverance.pdf
A key component of the Skycrane landing system is the device which allows the rover to be lowered by a distance of 7.0 m to fully extend its bridle, as the cord couldn’t be extended during entry through the planets’ atmosphere. This device - the Descent Brake Mechanism - allows this deployment to happen quickly and with controlled speed that decreases toward the end of deployment for a controlled landing at the full bridle length. Composed of a main generator, resistor board, and additional parts illustrated in Figure 4, this design lets the mechanism work in a way that doesn’t provide friction against the bridle as it deploys at a constant rate to its’ max length. A lack of friction and a high degree of control over the deployment lets the minimum amount of energy be released, which came out to around 24 kJ. This design has the advantage of being completely passive, and unlike previous friction technologies, also offers highly consistent performance over a wide temperature range.
Other very interesting EDL and rover specifics in a 2018 JPL Powerpoint presentation:
https://www.colorado.edu/event/ippw..._7_stilley_presid564_presslides_docid1142.pdf
And some interesting stuff I heard on the JPL net on YouTube before they cut it off. They really don't think anyone is interested in hearing this kind of stuff?
Cruise stage: 55.91 kg propellant remaining at separation
Descent stage: 401 kg propellant loaded, 305 kg used, 96 kg remaining