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Fraser
2019-Feb-16, 01:40 AM
A team of researchers has devised a new strategy for landing heavier craft on Mars, which could allow for crewed missions to the Red Planet.
The post Land Heavier Payloads on Mars. Aim for the Ground and Then Pull up at the Last Moment (https://www.universetoday.com/141485/land-heavier-payloads-on-mars-aim-for-the-ground-and-then-pull-up-at-the-last-moment/) appeared first on Universe Today (https://www.universetoday.com).


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cjameshuff
2019-Feb-16, 12:04 PM
SpaceX has been talking about using inverted lift transitioning to positive lift and supersonic retropropulsion for landing heavy payloads on Mars without parachutes since Red Dragon, and they didn't invent the concept. What's new about this study?

The paragraph quoted to support the statement about the high cost of retropropulsion actually directly contradicts it. The claim is made that retropropulsion costs payload mass and needs larger vehicles, but Prof. Putman talks about landing larger payloads by replacing parachutes with larger engines.

Also, the "Artistís illustration of a spacecraft using retropropulsion to steer" does not depict a spacecraft using retropropulsion.

And...

Beyond Mars, this study could implications for landing on other Solar bodies that have thin atmospheres.

...like what? Mars is the only one. The next object in ascending order of atmospheric density is Earth. The previous one is Pluto, and its atmosphere is too thin.

cjameshuff
2019-Feb-16, 01:52 PM
The "Artist’s illustration of a spacecraft using retropropulsion to steer" is actually an artist's illustration of Mars Science Laboratory's entry, at a point in its descent where it was using attitude control thrusters to steer. The retropropulsion came quite a bit later, after the parachute deployed, heat shield was jettisoned, and sky-crane/rover assembly dropped. MSL did not use retropropulsion for steering beyond obstacle avoidance at the very end, but did use a more limited version of the aerodynamic steering described, using those attitude control thrusters and 300 kg of ejectable ballast masses used to adjust its center of gravity. However, it only used the lift to compensate for errors in its trajectory, not to fly a more efficient reentry trajectory.