7 ms·

I wonder why the helicopter drop was necessary then but not now?

Simulacra 8y ago
The sky crane maneuver (as JPL called it) was necessary because if they descended propulsively to the surface, it could kick up a huge dust cloud. That dust could land on the rover and damage the instruments. See this awesome video: https://www.jpl.nasa.gov/video/details.php?id=1090 https://www.jpl.nasa.gov/video/details.php?id=1090
- mikepurvis 8y ago
  I think there was also concern about the hydrazine-fuelled landing rockets contaminating the site and instruments. Listening for quakes is not an activity which will be impacted by the surface being gunked up.
- dempseye 8y ago
  The audacity of that.
  - dsfyu404ed 8y ago
    I like to think some manager saw the army drop a humvee from a blackhawk and asked "why can't we do this, but on Mars?" and nobody came up with a good enough answer so they did it. Edit: Why is this comment unacceptable?
    - noonespecial 8y ago
      I always just figured Wile E. Coyote was on staff at the time and had his ACME catalog handy.
- spookyuser 8y ago
  Plus this awesome video: https://www.youtube.com/watch?v=gZX5GRPnd4U https://www.youtube.com/watch?v=gZX5GRPnd4U
- spullara 8y ago
  I was standing next to one of the engineers who wrote the software for the landing while we were watching on the big screen at Twitter. A few moments after it landed he announced that his code worked and was being deleted to make room for surface operations code.
  - dylan604 8y ago
    That's one of those cool things that never gets thought about outside the people directly involved. "Why keep the code required for landing readily available permanently, since it'll never ever need it again." That's one of the aspects that I enjoy about programming Arduino devices. I'm so spoiled to essentially unlimited memory on desktop/laptops (in comparison) that writing code to fit into extremely limited finite amounts of memory becomes challenging in a fun way.
  - jcims 8y ago
    I always wonder if there was any video released of the sky crane tests on Earth. I have to imagine they were done at some point, but I never saw it.
JeremyReimer 8y ago
I think it's because Curiosity was a rover and Insight is only a lander. A lander can have rockets on the bottom that slow its descent, but a rover can't, as then the wheels won't work. So the "helicopter drop" puts the rockets on a platform far above the rover (so the exhaust won't damage it) and then it flies away once the rover is on the surface.
- deathanatos 8y ago
  Spirit/Opportunity were both wheeled rovers, and both landed with something under them; they had ramps that unfolded after landing, and the rover then proceeded to drive off the ramp onto the surface. So I don't think putting things under the wheels is necessarily a non-starter. (But those rovers, IIRC, did a bounce-and-roll-to-a-stop style landing.)
  - hrydgard 8y ago
    The difference is that those rovers are a small fraction of the size and weight of Curiosity - the latter probably couldn't have survived a bounce-and-roll.
  - henrikeh 8y ago
    Curiosity was too heavy for the airbag-style landing: https://en.m.wikipedia.org/wiki/Mars_Science_Laboratory#Entry,_descent_and_landing_(EDL) https://en.m.wikipedia.org/wiki/Mars_Science_Laboratory#Entr...
detaro 8y ago
I'd guess: Insight isn't a rover and thus less sensitive to a bad landing/getting stuck.
NikolaeVarius 8y ago
Weight. Curiosity weighs over twice as much as Insight and needed a special heavy lift landing device. Insight doesn't need it, so no reason to spend the money on it.
ChuckMcM 8y ago
As I recall there was also something about the complexity of having the rover drive off the landing platform which was to be avoided. It would have been several feet of the ground and needed to get down.

The sky crane maneuver (as JPL called it) was necessary because if they descended propulsively to the surface, it could kick up a huge dust cloud. That dust could land on the rover and damage the instruments. See this awesome video: https://www.jpl.nasa.gov/video/details.php?id=1090 https://www.jpl.nasa.gov/video/details.php?id=1090

mikepurvis 8y ago
I think there was also concern about the hydrazine-fuelled landing rockets contaminating the site and instruments. Listening for quakes is not an activity which will be impacted by the surface being gunked up.
dempseye 8y ago
The audacity of that.
- dsfyu404ed 8y ago
  I like to think some manager saw the army drop a humvee from a blackhawk and asked "why can't we do this, but on Mars?" and nobody came up with a good enough answer so they did it. Edit: Why is this comment unacceptable?
  - noonespecial 8y ago
    I always just figured Wile E. Coyote was on staff at the time and had his ACME catalog handy.
spookyuser 8y ago
Plus this awesome video: https://www.youtube.com/watch?v=gZX5GRPnd4U https://www.youtube.com/watch?v=gZX5GRPnd4U
spullara 8y ago
I was standing next to one of the engineers who wrote the software for the landing while we were watching on the big screen at Twitter. A few moments after it landed he announced that his code worked and was being deleted to make room for surface operations code.
- dylan604 8y ago
  That's one of those cool things that never gets thought about outside the people directly involved. "Why keep the code required for landing readily available permanently, since it'll never ever need it again." That's one of the aspects that I enjoy about programming Arduino devices. I'm so spoiled to essentially unlimited memory on desktop/laptops (in comparison) that writing code to fit into extremely limited finite amounts of memory becomes challenging in a fun way.
- jcims 8y ago
  I always wonder if there was any video released of the sky crane tests on Earth. I have to imagine they were done at some point, but I never saw it.

JeremyReimer 8y ago

I think it's because Curiosity was a rover and Insight is only a lander. A lander can have rockets on the bottom that slow its descent, but a rover can't, as then the wheels won't work. So the "helicopter drop" puts the rockets on a platform far above the rover (so the exhaust won't damage it) and then it flies away once the rover is on the surface.

deathanatos 8y ago
Spirit/Opportunity were both wheeled rovers, and both landed with something under them; they had ramps that unfolded after landing, and the rover then proceeded to drive off the ramp onto the surface. So I don't think putting things under the wheels is necessarily a non-starter. (But those rovers, IIRC, did a bounce-and-roll-to-a-stop style landing.)
- hrydgard 8y ago
  The difference is that those rovers are a small fraction of the size and weight of Curiosity - the latter probably couldn't have survived a bounce-and-roll.
- henrikeh 8y ago
  Curiosity was too heavy for the airbag-style landing: https://en.m.wikipedia.org/wiki/Mars_Science_Laboratory#Entry,_descent_and_landing_(EDL) https://en.m.wikipedia.org/wiki/Mars_Science_Laboratory#Entr...

detaro 8y ago

I'd guess: Insight isn't a rover and thus less sensitive to a bad landing/getting stuck.

NikolaeVarius 8y ago

Weight. Curiosity weighs over twice as much as Insight and needed a special heavy lift landing device. Insight doesn't need it, so no reason to spend the money on it.

ChuckMcM 8y ago

As I recall there was also something about the complexity of having the rover drive off the landing platform which was to be avoided. It would have been several feet of the ground and needed to get down.