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Perseverance Rover lands on Mars [video]

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Re: Perseverance Rover lands on Mars [video]

#121

Post by teraflop »

_Microft wrote: post #110
Azrael3000 wrote: post #94

Earlier quoted context omitted.

That is most certainly correct. They also mentioned that these are images from engineering cameras, so they are normally responsible for navigation. The real HD footage will come in over the next hours as the bandwidth just is not large enough. Elon Musk needs to provide some Starlink sats for a better connection.

Starlink would most certainly be of little direct use here. What I could imagine is having Starlink satellites around Mars that allow to route data from rovers anywhere on the planet to a dedicated high-performance communications platform that handles communication with Earth.

In fact that's exactly what they're doing: the Mars Reconnaissance Orbiter is serving as a communications relay, as it did for previous landers.

It's just that since there have never been more than a handful of spacecraft active on Mars at any given time, there's currently no point in spending huge amounts of money to launch a whole constellation of satellites for continuous coverage.

Re: Perseverance Rover lands on Mars [video]

#123

Post by thelean12 »

marcinzm wrote: post #114
thelean12 wrote: post #98

Earlier quoted context omitted.

> Also, remind me, did NASA develop reusable rockets? I can't tell if this is sarcasm or not but... yes, of course NASA developed reusable rockets. The space shuttle missions reused the shuttles and the boosters.

The Space Shuttle was reusable (with massive refurbishing after each flight) but given that'd it cost significantly more than a non-reusable rocket per pound I think the point stands. SpaceX managed to make a financially viable reusable rocket.

> I think the point stands

No it doesn't. The person was trying to say SpaceX > NASA. Many people here are trying to shit on the other side as if they have a real point.

They're both doing cool and useful things and they're both really really good at what they do.

Re: Perseverance Rover lands on Mars [video]

#124

Post by notum »

joe_91 wrote: post #53
raphaelj wrote: post #47

NASA's ability of succeeding at landing things successfully on the first try on foreign bodies since 1969 is mind-blowing. Meanwhile, SpaceX takes half a dozen tries before managing to do the same on a fully known environment on Earth.

NASA also requires 10-100x more money & time to do so. Both just have very different ways of working. Both work and there are pro's and con's to either way!

I'll just leave Thunderf00t's latest video here: https://www.youtube.com/watch?v=4TxkE_oYrjU

Let's not diminish ether's breakthroughs, but financial isn't one of SpaceX's.

Re: Perseverance Rover lands on Mars [video]

#126

Post by mikeyouse »

pupdogg wrote: post #51

It took them approx. 4,881 hours from launch to land approx. 127,770,000 miles away. Is it safe to say that the average speed of the mission can be calculated as 436 miles/hour?

I think you dropped a thousands somewhere.. 127.8M miles/4,881hrs = 26,000 mph.[1]

But in reality, it obviously didn't fly in a straight line, Looks like it traveled closer to 292 million miles[2], so more like 60,000 mph.[3]

[1] - https://www.wolframalpha.com/input/?i=127800000+miles%2F4881...

[2] - https://mars.nasa.gov/mars2020/timeline/cruise/

[3] - https://www.wolframalpha.com/input/?i=292526838+miles%2F4881...

Re: Perseverance Rover lands on Mars [video]

#127

Post by jxcl »

handedness wrote: post #103
kaycebasques wrote: post #78

Earlier quoted context omitted.

N00b question: why is it black & white?

The world is a complicated place, Hobbes.[1] The lower "HazCams" hazard avoidance cameras (which captured those initial photos) are there to detect hazards (rocks, trenches, etc.). They are stereoscopic, lightweight, and high resolution. My guess is that using color sensors would have either increased the 3D mapping precision or added weight/power/bandwidth requirements, or otherwise been less robust in that environm…

> My guess is that using color sensors would have either increased the 3D mapping precision or added weight/power/bandwidth requirements, or otherwise been less robust in that environment.

I think you meant to say decreased? In which case I think you would be correct! Camera pixels are made up of these things called photosites which don't by themselves record color, only brightness. In order to record color information, the photosites are placed behind a Bayer filter[1], which effectively reduces the resolution of the camera by 3, because in order to get the color of a pixel you need its red, green and blue component. Bayer filters also frequently have a small blurring filter in front of them to make sure that nearby photosites with different color filters get the information they need.

If you're looking for the highest resolution image possible, black and white is the way to go!

[1]: https://en.wikipedia.org/wiki/Bayer_filter

Re: Perseverance Rover lands on Mars [video]

#128

Post by dmurray »

hedgehog wrote: post #122

I read that the design life of the helicopter is five flights. Does anyone know what the limiting factors are? The brutal cold and abrasive dust both seem like they could contribute but I am curious what the real answer is.

The "design life" figure is something like the 5th percentile, if previous rovers are anything to go by. As in, they can estimate a 95% chance it makes it through 5 flights.

I'd bet on it making 20+ at evens.

Re: Perseverance Rover lands on Mars [video]

#129

Post by ALittleLight »

thelean12 wrote: post #123
marcinzm wrote: post #114

Earlier quoted context omitted.

The Space Shuttle was reusable (with massive refurbishing after each flight) but given that'd it cost significantly more than a non-reusable rocket per pound I think the point stands. SpaceX managed to make a financially viable reusable rocket.

> I think the point stands No it doesn't. The person was trying to say SpaceX > NASA. Many people here are trying to shit on the other side as if they have a real point. They're both doing cool and useful things and they're both really really good at what they do.

I'm not trying to say that SpaceX is better than NASA. I am responding to the point that NASA has done things that SpaceX hasn't (e.g. landing on other celestial bodies) by pointing out that SpaceX has done things NASA hasn't (e.g. SpaceX rockets land and can be reused).

I don't think it makes sense to talk about which is better unless there is some specific metric that can be measured so a conclusion could be reached. I am encouraged though that SpaceX has a trajectory that will allow greater access to space. By bringing the cost of space travel down, I expect we will get a lot more of it. NASA (and other governmental space programs) started the initiative, but I think SpaceX is continuing it marvelously.

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