Ingenuity- Mars 2020 Helicopter, Deployment & Operations Options

[Art Martin]

I'm putting this in the Early Drives category because I believe that one of the primary purposes of these first drives is to find a spot for the helicopter.

Is anyone else wondering like I am just what the terrain needs to look like to set the helicopter down? It sure looks to me that the areas we're in right now are largely free of obstacles for flying and landing with no large rocks. Unless you go for some completely sand covered spot I'm not sure you're going to find any areas any more pristine. Does anybody have any info about what type of zone they are exactly looking for? Since the helicopter is not really designed to be used for investigation of terrain but more as just a proof of concept of flight, I would imagine the choice of area would be wide open and flat.

Here's what I've got so far about upcoming events.

1. The helicopter below the rover limits ground clearance so it is vital that the helicopter phase be early in the drives so the rover is not limited in mobility.

2. The main purpose of the helicopter is proof of concept of Mars flight so the emphasis is not using it for exploration/route planning/research photography but merely that we can sustain flight - take off, fly autonomously, and land safely.

3. Once deposited on the surface, it will take a number of days of check outs prior to the first real flight.

Should we create a new topic that is discussion about the helicopter?

[Bill Harris]

The parachute was designed to make a controlled descent for the Skycrane to make a perfect landing. Certainly that is substantial damage to the Backshell. One might expect that once the Skycrane+Rover departed from the Parachute+Backshell that the weight would be greatly reduced and the Chute, et al, would drift lazily away. I imagine that the designers expected that too, and feared that the Chute would interfere with the Landing, and collapsed the Chute so it would impact away from the Landing area.
Or so it would seem

--Bill

[djellison]

One might expect that once the Skycrane+Rover departed from the Parachute+Backshell that the weight would be greatly reduced and the Chute, et al, would drift lazily away. I imagine that the designers expected that too, and feared that the Chute would interfere with the Landing, and collapsed the Chute so it would impact away from the Landing area.
Or so it would seem

.....


And look at the "gash" on the right side of the Chute. This Chute was intentionally disabled.

No. That 'gash' is part of the disk-gap-band design of the parachute.

https://mars.nasa.gov/resources/24989/wind-...nces-parachute/

Drag scales with the square of the velocity - so even when the powered descent vehicle drops out of the backshell and the mass is dropped to ~20% of what it was....the speed only reduces by a little over half to something like ~80mph ( the JPL release says about 78 )

Without the heatshield in place - the bottom of the backshell crashing into the ground at fast freeways speeds is frankly the absolute worst case for structural integrity of the backshell - it's little surprise it has broken up as much as it has.

Collapsing the chute would be a bad idea - that would have accelerated the backshell and increased the likelihood of a recontact issue with the powered descent vehicle. No EDL has done this. You want the backshell and parachute to take their time to drift in the breeze and end up far, far away. The divert maneuver as part of the powered descent phase is also to help reduce the recontact problem.

Everything in the Ingenuity images is consistent with the backshell and 'chute landing normally - at an expected terminal velocity with an intact and fully inflated chute.

[serpens]

....Drag scales with the square of the velocity - so even when the powered descent vehicle drops out of the backshell and the mass is dropped to ~20% of what it was....the speed only reduces by a little over half to something like ~80mph ( the JPL release says about 78 )....

I would have thought that following the Mars Climate Orbiter failure the Imperial system would be verboten for any purpose within NASA and only the metric used, or is this a conversion for public consumption.

[mcaplinger]

I would have thought that following the Mars Climate Orbiter failure the Imperial system would be verboten for any purpose within NASA...

Well, you'd be wrong. And I grow quite weary of hearing that since I worked on that project for years and know exactly what happened. It was far more than a simple units mixup. [mods, feel free to delete this exchange as it is off-topic.]

[MarkL]

Well, you'd be wrong. And I grow quite weary of hearing that since I worked on that project for years and know exactly what happened. It was far more than a simple units mixup. [mods, feel free to delete this exchange as it is off-topic.]

Off topic but worth discussing and it must have been a wonderful experience to have been involved in that project, a job most of us amateurs could only dream of. I think the reason the public still considers the mishap to have resulted from a measurement unit mixup is because the board stated:

"The MCO MIB has determined that the root cause for the loss of the MCO spacecraft was the failure to use metric units in the coding of a ground software file, “Small Forces,” used in trajectory models. Specifically, thruster performance data in English units instead of metric units was used in the software application code titled SM_FORCES (small forces). A file called Angular Momentum Desaturation (AMD) contained the output data from the SM_FORCES software. The data in the AMD file was required to be in metric units per existing software interface documentation, and the trajectory modelers assumed the data was provided in metric units per the requirements."

http://sunnyday.mit.edu/accidents/MCO_report.pdf

But as was also stated, the real problem was the fact the error went undetected which has little to do with the SI vs Imperial debate. The concept of error detection is certainly topical when discussing any remote mission, including Ingenuity, and probably what was learned after the MCO mishap has reduced the risk of all subsequent missions considerably.