Perseverance snaps its first picture of grounded Ingenuity
Click for interactive map.
Click for original image.
Perseverance on February 4, 2024 finally moved into a position where it was close enough to take its first picture of the now grounded Ingenuity helicopter. That picture, cropped, reduced, and enhanced to post here, is to the right, taken by the rover’s left high resolution camera. You can see Ingenuity sitting on the slope of a dune near the upper right.
The overview map above provides the context. The green dot marks Ingenuity’s final resting spot. The blue dot marks Perseverance’s present location, with the yellow lines indicating approximately the area covered by the photo.
Whether the rover is now close enough to get good imagery for a final engineering test of Ingenuity — where its rotors will be rotated and shifted slowly to determine the extent of the propeller damage — is not clear. Perseverance could move much closer, but its science team might not want to cross these dunes out of fear the rover would get stuck. They might move forward a few more feet, to the top of the south bank of Neretva Vallis, before doing that test.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Click for interactive map.
Click for original image.
Perseverance on February 4, 2024 finally moved into a position where it was close enough to take its first picture of the now grounded Ingenuity helicopter. That picture, cropped, reduced, and enhanced to post here, is to the right, taken by the rover’s left high resolution camera. You can see Ingenuity sitting on the slope of a dune near the upper right.
The overview map above provides the context. The green dot marks Ingenuity’s final resting spot. The blue dot marks Perseverance’s present location, with the yellow lines indicating approximately the area covered by the photo.
Whether the rover is now close enough to get good imagery for a final engineering test of Ingenuity — where its rotors will be rotated and shifted slowly to determine the extent of the propeller damage — is not clear. Perseverance could move much closer, but its science team might not want to cross these dunes out of fear the rover would get stuck. They might move forward a few more feet, to the top of the south bank of Neretva Vallis, before doing that test.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Oh crap, it landed next to the peak of a dune.
I bet that’s what did it.
Yes
It looks like it took a hard landing on a tilted surface.
It might have even buried its landing gear into the sand. Maybe to deep to take off again.
Slightly enhanced, with magnified inset by UMSF member “tau”.
http://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=54545
From this angle and shadows, there doesn’t seem to be much of the rotors left. I’m sure this is just an optical illusion. In my experience with quad rotor drones, touching ground on landing is not good for the blades. I am surprised Ingenuity is still upright.
Regarding Jeff’s comment: Since it has counter rotating blades perhaps the impact forces on the blades were balanced enough that the craft was left standing rather than falling over??
It looks like the two uphill feet touched down and slid before the downhill feet touched. Or is that brown spot on top of the dune the gouge made by the rotors as they broke off? I am curious as to what happened, and I am disappointed that Perseverance is unlikely to approach Ingenuity for a close look and analysis.
So here comes my question: how far would they have been thrown?
To answer this question we can determine a couple of things, such as the speed of the rotor tips when they departed the Marscraft. The rotors are 4 ft. diameter, or 2 ft. radius. We know that they rotate at around 2700 rpm (between 2400 and 2900 rpm), 45 revolutions per second. Making an assumption about how much broke off gives us an approximate center of mass of the broken off part and gives its radius from the spin axis. Assuming that around 1/4 of the blades broke off (maybe a little more) then the radius of the center of mass is around 1-3/4 feet, or about 0.53 meters, which I round down to 1/2 meter for ease of calculation of this approximation.
Equation 1: v = r * w,
Where:
v is velocity,
r is radius = 1/2 meter, and
w is omega (lower case) is rotation speed in radians = 45 rpm * π * 2 = 280 rad/sec.
Therefore:
v = 1/2m * 280rad/s = 140 meters per second.
Assuming that they were thrown from their just-under 1/2 meter height (rather than being tossed at an angle into the air due to striking the ground), we can calculate the time they would have taken to fall to the ground.
Equation 2: s = (1/2) * a * t^2,
Where:
s is distance to the ground = 1/2 meter,
a is acceleration of gravity = 0.37 m/(s^2), and
t = time taken to reach the ground.
Rearranging Eq 2:
t = √(s * 2 / a) = √(1/2m * 2 / 0.37m/(s^2)) = 0..52 sec
The distance thrown in 0.52 seconds is given by:
Equation 3: d = v * t,
Where:
d is distance thrown.
Therefore:
d = 140 m/sec * 0.52 sec = 73 meters (240 ft)
Precision is less than one significant digit, especially since the rotation rate is likely on the lower end, around 2400 rpm, during landing. This rate would give a rotation of 40 revolutions per second, a w of 251 rad/sec, a v of 125 m/sec, and a distance thrown of 65 meters (210 ft).
My conclusion:
Since they were counterrotating, and since they most likely all broke off at the same location on the ground, two would have flown in one direction, and the other two would have flown off in the opposite direction.
Even if after falling distance d they didn’t continue skidding along the ground like a skipping stone on water, weren’t still generating lift, weren’t fluttering randomly all over the countryside, and didn’t land on the far side of a dune, I don’t think Perseverance is likely to find them if it searched, and it is even less likely to stumble across any of them on its continued journey.
Of course, this assumes that the composite structure of the blades remained intact and did not shatter when they struck the ground and broke off. I like this assumption, because otherwise I think the picture from Perseverance would show some debris from the blade material.
_______________
Jeff,
Thank you for that slightly enhanced image.
Until it gets closer we have no idea exactly how much has been removed.
My guess it tilted and struck the ground and the force of the blades hitting the ground knocked the machine back up.
My guess is the two blades actually struck each other and that might have been the major damaging factor, The ground does not look like it would have been hard enough to grind off the tips.
pzatchok wrote: “The ground does not look like it would have been hard enough to grind off the tips.”
If my calculation of 140 meters per second is about right, that speed is close to 300 miles per hour. Hitting sand at that speed could be forceful enough to knock them off rather than grind them. This was my thinking in figuring out how far the pieces may have been thrown.
However, if they were ground off, perhaps by multiple contacts with the sandy dune, this may explain why the shadows did not show signs of threads remaining from the fiber portion of the rotors.