I'd love to see this video with some real-time overlays. Landing spot identification with a 90% confidence zone, hazard identification, altitude, etc. I'm also curious how much hazard identification was done in real time versus a pre-programmed map.
Perseverance rover’s descent and touchdown on Mars [video]
81–90 of 152 posts
Re: Perseverance rover’s descent and touchdown on Mars [video]
#82Earlier quoted context omitted.
We know how to land relatively small things on Mars landing humans will be a much larger craft and because of that a harder task.
But you don't have to worry that much about kicking up a lot of dust (the self-loading meatbags on board can clean your solar panels) so you can just point your thrusters at the ground and play with the throttle a little
It's not just the landing, that's relatively simple and can be mostly done with bigger thrusters on the craft but you have to slow down a lot before you can safely. Right now that's done through a heat shield then a parachute and finally the actual propulsive landing of the SkyCrane. We've done some testing of inflatable shields for the first step but nothing practiced actually in the Martian atmosphere yet and parachutes aren't great for heavier things.
You want to use the other two to slow down as much as possible so you're not hauling extra fuel all the way to Mars. Ideally you'd be using ISRU units to generate your return fuel too.
Re: Perseverance rover’s descent and touchdown on Mars [video]
#83Earlier quoted context omitted.
It got sent back via orbiters ranging from the ESA's Trace Gas orbiter, the Mars Reconnaissance Orbiter or Mars Odyssey. Through those they can get up to 2 megabits per second [0] back to earth but that depends a lot on the orbiter it's talking to at a given time. The TGO is doing a lot and is one of the early high speed relays for the data from Perseverance. [1] There's also direct links to and from Earth but they'r…
The more impressive part is that the sky crane shot pictures, video and data and had to download everything to the rover before it was cut loose. As soon as the rover wheels touched ground, the tether was cut and the lander flew away.
That's relatively simple just wire them directly into the rover to start with so the data is always in the right place.
Re: Perseverance rover’s descent and touchdown on Mars [video]
#84I don't know why I'm surprised at the amount of footage and the quality, but I am. This is really setting a new bar for missions like this, similar to what SpaceX has done in recent years. Stuff like this has got to be huge for getting interest and excitement from the general public and especially kids.
I still can't get over the fact this mission has legit good cameras on it.
Re: Perseverance rover’s descent and touchdown on Mars [video]
#85So glad they've realized the value in allowing everyone to experience how hard these things are. So impressive, I can't wait to watch this video over and over. The inflation of the parachute is spectacular, and knowing how hard it is, and how hard it is to test on earth - its just incredible. And the skycrane was flawless - just so impressive how well it works. Too bad it flies off to crash and can't land gently some…
If there was mass available to add something to the sky crane, you'd be better off putting that thing on the rover, since the rover has the plutonium power pack. I do feel a bit sorry for the crane as well though :)
This is what I was thinking. That sky crane has to be as barebones as can possibly be made. Every single bit of mass on it is something that could be better used elseware.
Tradeoff of course is if you skimp on the mass too much you'll get an unreliable sky crane and the whole thing is a dud.
Re: Perseverance rover’s descent and touchdown on Mars [video]
#86Can someone comment on why this is the first time I'm seeing videos from Mars versus previous missions. Did the memory write speeds increase, more sensitive CCD sensors, easier to send data back to Earth? I'm sure there must be some technological reason this wasn't done before because it's simply stunning...
The commercial cameras have gotten so good over the years so they could put cameras everywhere. They added some local storage to retain images for post processing. They post process the videos to a much smaller file before transmitting. So of-the-shelf technology keeps getting better.
Re: Perseverance rover’s descent and touchdown on Mars [video]
#87Earlier quoted context omitted.
At about 2:57 the operator says the rover is about 20 meters off the surface, if that helps at all. I agree it got really hard to get a sense of the scale once the thrusters started blowing up dust.
I rewatched listening to all that and it helped but only in an abstract way. It's like there needs to be a penny in the shot or something to get a sense of scale.
No, not a penny. It needs a banana for scale
Re: Perseverance rover’s descent and touchdown on Mars [video]
#88Can someone comment on why this is the first time I'm seeing videos from Mars versus previous missions. Did the memory write speeds increase, more sensitive CCD sensors, easier to send data back to Earth? I'm sure there must be some technological reason this wasn't done before because it's simply stunning...
It didn't have priority until now. Everything costs time and money and adds more complexity, more parts that can cause a failure. While videos are nice, they don't have such scientific value as another scientific instrument that could have been on board instead.
> While videos are nice, they don't have such scientific value as another scientific instrument that could have been on board instead.
While they don't have much scientific value, they have an extreme amount of value in a related field: marketing.
I mean, if you want more money for your hot new space rover mission nothing sells it better than high resolution quality videos of it landing on the surface of another planet.
Re: Perseverance rover’s descent and touchdown on Mars [video]
#89Earlier quoted context omitted.
1% atmospheric pressure would do that. Sound won't travel very well through the Martian atmosphere.
Wow, very interesting. I had a pre-conceived notion that Martian atmospheric pressure was something like 20% of ours, but you're right, it's quite a bit lower than even that.
If only.
>The minimum safe lower limit for the partial pressures of oxygen in a gas mixture is 0.16 bars (16 kPa) absolute.
https://en.wikipedia.org/wiki/Partial_pressure
If it was 20% that would be survivable with just an oxygen mask fwiw. Humans can go down to 16% atm pressure safely if they breathe 100% oxygen. The rest of the body can easily handle the pressure difference (1 full atm of pressure is equivalent to being 10meters underwater as a guide, human orifices have no issue with it contrary to pop sci beliefs).
So yes it's not 20% and it would be nice if it was.
Re: Perseverance rover’s descent and touchdown on Mars [video]
#90As it got closer to the ground, it seemed really hard to get a sense of scale with that downward camera. It felt like the ground just kind of "appeared" right before the sky crane did its thing. How big are the rocks under it? It felt like they were either big (1+ meter) or just little pebbles. I really couldn't tell. Either way, this is seriously the coolest video I think I've ever seen. I cannot wait for more.
Hah, totally agree. I assume the thinner atmosphere causes the dust to behave as if our view is much closer to the ground than it actually is.