Sorry Bruce but in your own words, ow did they work that out? :-p
It does.
Amazing. Guess they might on future missions.
Itās called mathematics or statistics to be more precise. Why?
https://www.reuters.com/article/idUSKBN2AJ2L5
Propulsion Laboratory (JPL) near Los Angeles less than 24 hours after the landing.
The picture, looking down on the rover, shows the entire vehicle suspended from three cables unspooled from the sky crane, along with an āumbilicalā communications cord. Swirls of dust kicked up by the craneās rocket thrusters are also visible.
Seconds later, the rover was gently planted on its wheels, its tethers were severed, and the sky crane - its job completed - flew off to crash a safe distance away, though not before photos and other data collected during the descent were transmitted to the rover for safekeeping.
The image of the dangling science lab, striking for its clarity and sense of motion, marks the first such close-up photo of a spacecraft landing on Mars, or any planet beyond Earth.
Next week, NASA hopes to present more photos and video - some possibly with audio - taken by all six cameras affixed to the descending spacecraft, showing more of the sky crane maneuvers, as well as the supersonic parachute deployment that preceded it.
Being a part of this, what an achievement.
Nice, Longdogs!
Scroll down on this link and youāll find two clips where you listen to the first recordings of a Martian breeze. 
More pictures arriving from the Mars Rover on the Martian surface:
[CENTER]https://i.chzbgr.com/original/6487817728/h3A831235/
https://www.dbtechno.com/wp-content/uploads/2012/08/mars-photo-meme1.jpg[/CENTER]
Iām grabbing and sharing these, Bruce!
Empty water bottles are surely next.
They have recording of what they believe is a a quake by NASAās InSight.
Love it Bruceā¦
Mars helicopter may have taken off in a 30 second flight.
The data takes hours to get back over the distance between Mars and the Earth, however. Nasa will not announce how the flight went ā or whether it did ā until 11.15am UK time.
Hope it was a success. 
The American space agency has successfully flown a small helicopter on Mars.
The drone, called Ingenuity, was airborne for less than a minute, but Nasa is celebrating what represents the first powered, controlled flight by an aircraft on another world.
Confirmation came via a satellite at Mars which relayed the chopperās data back to Earth.
Chopper on Mars ā¦ :shock:
Well done, NASA ā¦ 
Apparently the new Mars rover is slowing down,
It is believed that dust settling on the voltaic cells is blocking light
from reaching the cells an thus reducing voltage to the batteries ??
Meanwhile the old lander has been perambulating around the
Martian landscape for l think a couple of years now?
Perhaps they should call the window cleaner ??
Donkeyman!
Apparently the atmosphere on Mars is only a fraction of that here on Earth, so the rotor blades have to be very large to scoop enough air to get it to rise. Our own helicopters can only fly up to a certain height before there is not enough air to keep them airborne.
Quote:
Turbine-engined helicopters can reach around 25,000 feet. But the maximum height at which a helicopter can hover is much lower - a high performance helicopter like the Agusta A109E can hover at 10,400 feet.
A lot lower on Mars.
I donāt think dust on the solar panels is anything new. I am sure I read somewhere that one of the vehicles on Mars shut itself down because of dust on the cells leading to low voltages in the battery however a Martian wind blew the panels clean again and, much to the surprise of the controllers on Earth, it rebooted itself and carried on as if nothing had happened.
Or was it the Martians that gave it a quick wipe over? Either way the software seems pretty clever and resilient as nothing can be controlled from Earth in real time.
I read that the rotors spin at about five times the rate on Mars. The good news is that there would be less resistance when on a good run 
.
Mars has an atmosphere but it is not like Earths at all I seem to remember that it is mostly carbon dioxide (that could be wrong) and that it is only 1% that of our atmosphere.
Mars is also much smaller than Earth because Jupiter swept in and cleaned planet forming debris from its orbit (thank you Brian Cox) so running would be a lot of fun if you had not died from lack of oxygen/atmosphere lost because of its smaller mass.
Your numbers are about right and yes, one would have to have a healthy supply of O2 in tow.
Though it is still quite low, there is a very surprising, above predicted, rise of oxygen on Mars during its spring and summer months. There are both abiotic and biotic possibilities for this increase which has everyone scrambiling.