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Has NASA studied whether the Hypersonic Inflatable Aerodynamic Decelerator could allow for a skip-entry*, or anything other than direct entry to Mars, to aid in a craft's deceleration?

*Skip-entry or boost-glide trajectories allow for craft entering an atmosphere to extend the range the craft is in the upper atmosphere and more time for the craft to slow down rather than a going directly to the ground in a ballistic trajectory, "straight down."

Image of Earth to illustrate the concept for Mars entry.

enter image description here

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    $\begingroup$ maybe everyone else but me knows, but what is a "skip-entry"? $\endgroup$ – uhoh Dec 17 '19 at 5:52
  • $\begingroup$ The linked article appears to be a mechanism for helping landing on bodies with atmospheres, and doesn't mention "skip entry" at all. Is this about aerocapture or aerobraking or something? $\endgroup$ – Starfish Prime Dec 17 '19 at 11:14
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    $\begingroup$ A picture of Earth in a question about Mars? $\endgroup$ – Uwe Dec 17 '19 at 15:31
  • $\begingroup$ @uhoh Skip entries are when you skip the entry phase altogether and blow past your target. $\endgroup$ – BMF Dec 17 '19 at 16:40
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    $\begingroup$ I guess skip-entry has one significant problem - there is much more uncertainty for landing point than for direct entry. It could significantly limit accessible landing areas on Mars. $\endgroup$ – Heopps Dec 30 '19 at 6:26
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Earth has a much larger and fluffier atmosphere than Mars. Mars’ atmosphere provides little deceleration until about 50km or below (depends on location and angle), but then the deceleration turns on quite solidly.

The result is a very narrow window to do any maneuvering in the brief interval that the speed is dropping.

Source, originally from Aerothermodynamic Design of the Mars Science Laboratory Backshell and Parachute Cone

enter image description here

enter image description here From the (paywalled) paper discussed here.

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    $\begingroup$ The image was too small to see so I replaced it with a Wikimedia commons copy, though the x-axis is now in French. Feel free to roll-back or edit further. $\endgroup$ – uhoh Dec 30 '19 at 6:16
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    $\begingroup$ I'm not sure how to quantitatively compare the "fluffiness" of Mars' versus Earth's atmosphere, but you can compare scale heights. It might be interesting to calculate which one is actually "softer" (i.e. larger scale heigh, more gradual increase in density) $\endgroup$ – uhoh Dec 30 '19 at 6:17
  • $\begingroup$ In wikipedia article skip-entry is defined to happen in the "high upper atmosphere", but the way the black curve shows local increase of altitude in the first plot (in vicinity of 1.6km/s, 14km) looks essentially as skip-entry, but in the lower atmosphere. It is interesting, what caused this effect? $\endgroup$ – Sergiy Lenzion Dec 30 '19 at 21:37

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