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The Mars Helicopter Is Online and Getting Ready to Fly

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Re: The Mars Helicopter Is Online and Getting Ready to Fly

#211

Post by shellfishgene »

jefft255 wrote: post #2

I am incredibly excited for this. Can believe how nervous the control engineers must be for this. Not sure what quality of the footage to expect from this.

I was also excited about it, however an article critical of various points of Mars 2020 damped this quite a bit [1 (in German)]: Does the drone actually have any scientific relevance? I'm even doubtful it answers relevant engineering questions. I mean, it was tested in a pressure chamber already simulating mars atmosphere and gravity, we know it will work. The only question seems to be: Will it fail because of some engineering oversight or hardware failure, or not? There seem to be no scientific sensors on it at all. This 'commodity hardware test' could also be done with just the processor and monitoring, without the helicopter part. Looking at it like this it seems like mostly a toy or PR stunt, but one that takes $80M and space on the rover away from scientific projects.

[1] https://www.golem.de/news/perseverance-diese-marsmission-hat...

Re: The Mars Helicopter Is Online and Getting Ready to Fly

#212

Post by ChuckMcM »

zhoujianfu wrote: post #204
ChuckMcM wrote: post #150

Earlier quoted context omitted.

And given the density of Venus' atmosphere, here is a fun thought experiment. It may be possible to make 'titanium' balloons for longer term operation. The would work by creating the balloon envelope on earth, have a sealing mechanism that you activated in orbit so they had vacuum inside. And then drop them into the atmosphere. Same idea a glass floats on fishing nets[1] except with titanium (so they can withstand th…

Does anybody have any thoughts on how feasible it would be to make a metal “vacuum sphere” that floated in earth’s atmosphere? That’d be pretty cool! How huge would it have to be? Would it have to be made of titanium? Aluminum? Stainless steel? How good are those materials at withstanding a vacuum (or partial vacuum) if the diameter was say... 50m? I feel like at some size it must work, as the volume of air displaced…

The challenge is that Earth's air isn't dense enough. That said, the math is "easy" density is volume/mass, vacuum adds no mass, so it is just material mass / volume.

A 20cm diameter diamond sphere that was .5mm thick would have a mass of about 41g, a 20cm diameter sphere of air at sea level and "room" temperature is about 50g. So you would get 9g of "lifting force" from such a balloon (assuming I did all the calculations correctly). And experience about 2,900lbs of compression force.

Any air in the sphere would add weight.

Re: The Mars Helicopter Is Online and Getting Ready to Fly

#213

Post by buzzerbetrayed »

tachyonbeam wrote: post #124
TedShiller wrote: post #119

Earlier quoted context omitted.

A balloon is barely an aircraft

A solar drone that takes hours to charge and flies only a minute at a time is barely an aircraft too. Don't get me wrong, it's a very cool tech demo and I can't wait to see the video, but IMO if your goal is to take pressure/composition measurements in the atmosphere at a variety of altitudes, a weather balloon is the right tool for the job.

Nobody is arguing that it isn't the "right tool for the job". Just that a balloon isn't an aircraft. While a drone that flies for a minute at a time clearly is.

Re: The Mars Helicopter Is Online and Getting Ready to Fly

#214

Post by 8bitsrule »

cpgxiii wrote: post #206
layoutIfNeeded wrote: post #9

>One of the most significant obstacles for landing on Mars will continue to present problems for our heroic helicopter now that it is safely on the surface. The atmospheric pressure on the surface of Mars is only about 1% that of Earth. To put that in perspective, the summit of Mount Everest has only one-third the atmospheric pressure of sea level. While this is thought to be at (or sadly in some cases beyond) the li…

It should be clear that while Eurocopter and Aerospatiale before them liked showing off specific modified helicopters in the Himalayas (up to and including landing on Everest), none of them were capable of carrying a useful payload to that altitude. Helicopter altitude records are much like zoom-climb records in jet aircraft - yes, you can reach those altitudes, but not for long and not while doing anything else.

Everest landing video (2014). https://www.youtube.com/watch?v=WXNXSvnCtKA

Some current records. https://pilotteacher.com/how-high-can-you-go-in-a-helicopter...

Re: The Mars Helicopter Is Online and Getting Ready to Fly

#215

Post by tempestn »

thaumasiotes wrote: post #201
simcop2387 wrote: post #181

Earlier quoted context omitted.

Weight and volume. The air has weight so it'll cost more to launch. The volume would also make them more difficult to launch. Assembling or unfolding in space near earth would allow you to make them larger and inspect them before they leave for venus.

> Assembling or unfolding in space near earth would allow you to make them larger and inspect them before they leave for venus. Don't we want them to be rigid spheres?

Yes, but you could still construct it in orbit. Imagine building four quadrants, spooning them together for launch, then fusing ("cold welding") them into a sphere in space.

Re: The Mars Helicopter Is Online and Getting Ready to Fly

#216

Post by tempestn »

dal wrote: post #105
alpaca128 wrote: post #100

Earlier quoted context omitted.

> ...arguably the first _powered_ flights were done by the sky cranes of Opportunity and Perseverance Not the Apollo 11 lunar module? In contrast to the sky cranes it actually lifted off again.

The moon is not a planet.

Technically the moon is a dwarf planet, as it has sufficient gravity to form itself into a spheroid shape, but it has not cleared its orbit.

Re: The Mars Helicopter Is Online and Getting Ready to Fly

#217

Post by thaumasiotes »

tempestn wrote: post #215
thaumasiotes wrote: post #201

Earlier quoted context omitted.

> Assembling or unfolding in space near earth would allow you to make them larger and inspect them before they leave for venus. Don't we want them to be rigid spheres?

Yes, but you could still construct it in orbit. Imagine building four quadrants, spooning them together for launch, then fusing ("cold welding") them into a sphere in space.

It is surely better to construct them here, where we have all our tools, and if really necessary pump them out here. There just isn't an advantage to doing it in space. You end up paying more to create a lower-quality sphere.

And what weighs more - the air that got trapped in the sphere when we made it, or the machine we sent up to space to assemble a sphere there?

Re: The Mars Helicopter Is Online and Getting Ready to Fly

#218

Post by tal8d »

cpgxiii wrote: post #205
NikolaeVarius wrote: post #145

Earlier quoted context omitted.

What. I dont understand how you can make this claim. Guided bombs are NOT using CV with optical cameras. They use lasers, GPS, and other non "fancy" techniques. I just don't get in what world you think military munitions are using CV for targeting bombs.

The other poster mentions analog techniques used in contrast-tracking TV-guided munitions like the Walleye, but digital "CV-like" image/contour matching methods were used on the original Tomahawk cruise missile and the Pershing 2 missile to provide terrain-matching navigation and target guidance. GPS was neither sufficiently complete or accurate for strategic weapons in the late 1970s/early 1980s. In more modern weap…

> analog techniques used in contrast-tracking

aka edge detection :) I don't remember if it was the Sidewinder or Walleye that eventually dropped in a CCD (or both), but I know that the Maverick (which is technically older than Walleye) got along without a CCD until the GWOT - when it finally upgraded. The Javelin actually beat Maverick in that regard, having a 64x64 sensor 10 years earlier - able to handle scaling and perspective change for the 2-d designated target pattern.

https://apps.dtic.mil/dtic/tr/fulltext/u2/a454087.pdf

Re: The Mars Helicopter Is Online and Getting Ready to Fly

#219

Post by feralimal »

The mars atmosphere is equivalent to 120,000 feet.

The record altitude for a helicopter on earth is 40,820 feet.

How are helicopters able to fly so high on Mars?

Also, parachutes do not open when the altitude is greater than 15,000 feet.

How was the rover able to land at all with parachutes, in an atmosphere equivalent to 120,000 feet?

Re: The Mars Helicopter Is Online and Getting Ready to Fly

#220

Post by feralimal »

feralimal wrote: post #219

The mars atmosphere is equivalent to 120,000 feet. The record altitude for a helicopter on earth is 40,820 feet. How are helicopters able to fly so high on Mars? Also, parachutes do not open when the altitude is greater than 15,000 feet. How was the rover able to land at all with parachutes, in an atmosphere equivalent to 120,000 feet?

https://www.youtube.com/watch?v=uKEBHliLEYw
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