How did China know how to make their rover without sending a bunch of probes onto Mars? Did NASA share its data and info with China so that they knew what specs to make the solar panels, etc?
CNSA did acknowledge that they benefited from prior explorations to mars done by everyone, including NASA, soviet union, ESA and more. They are able to find general scientific data on mars, such as atmospheric density, composition, potential weather events, general topography in the public domain (I mean, wikiepdia has a lot of these information). For these, they should and are appreciating scientists going before them are sharing these information in the public domain. But I am sure NASA and everyone else did not release all super detailed data, such as detailed topology maps. And from public available info, they also know about general designs of NASA's landers and rovers, and the troubles NASA has faced operating these crafts on mars. If they learn from NASA's experiences, they can avoid a huge amount of unknowns and negative encounters. These are significant assistance when you are engineering systems. The pioneer is always way more difficult. So of course respect is paid and hats off to NASA and other pioneers.
But knowing these are not enough for you to build and operate a fully successful mission. Even if you had the entire CAD file of a NASA lander and rover, you don't know why they are designed that way, you will not operate, use and troubleshoot issues correctly. You need to build the system from ground up, so the people on your teams have full understanding of every single "why" and "how". Only then will you have full control and ensure the mission is success.
I am sure you had experience taking ownership to a software project written by others. You always have go to the original designer to ask "why" and "how". The knowledge transfer often last months and countless meetings. If you don't fully understand, you can't fix issues or build new features. Most people would rather build their own then to fix something they don't fully understand.
For CNSA, they can access public available data. Then they have to simulate, wind tunnel tests, how to land, what shape of lander they need, how to balance and control the lander etc. They need to build up their understanding of the entire system. They actually has been improving their technology and understanding of atmospheric and controlled powered landing from earth and moon missions. One of things they did differently is adding a flap to the lander to stabilize it in flight, they said it was to increase the lander's robustness when encountering more extreme weather.
For solar panels, knowing the distance to the sun, the atmospheric density, pressure, composition, force of gravity on mars, you can estimate the theoretical max of the solar energy available per unit of area. Then you could say assume only 30% is available due to weather. I am sure they have more advanced ways to estimate. Interesting fact about the rover, it has a solar heat capture and retention system. And they use the heat for thermo-control at night instead of electricity captured from solar panels, saving electricity use.
For where to land, topology and maps of mars is in public domain. You can find a general region where to land but these data are not detailed enough to actually land. And mars surface could have changed since these were captured. So tianwen-1 contains a orbiter and the lander. The orbiter has instruments such has high resolution imaging. They arrived mars orbit in February, and the 3 months since the orbiter was collecting data on mars. From these data they finalized their landing plans.
This is China's first spacecraft to ever travel this far. They also don't have communication network between mars and earth. So Tianwen-1's orbiter is also a communication satellite.
The impressive thing is the engineering side, how they engineered the system that each component all worked correctly in one go. The rocket: the rocket required to launch tianwen-1 (weighs 5 tons) to mars orbit was only tested successfully in dec 2019. China also doesn't have earth mars communication satellites and fully operational deep space communication system before this mission. This the first time all these system are tested live. To fly a spacecraft to mars for the first time, have it being captured by mars, and orbit mars correctly. Take data on mars. Release the lander. The lander going through atmosphere, releasing parachute at super sonic speeds, the lander detaches from parachute and uses a rocket engine to fly. At height of 100m, optical imaging and laser maps out the ground and autonomously navigate the craft to soft land on flat ground. Orbiter forms communication link between mars rover and earth. Mars rover collects sun light, drives, survives the elements of mars (so far).
Overall, they are standing on the shoulders of people who went before them. One shouldn't look down on their success, nor should they over-hype their success.
CNSA said Zhurong landed 3km away from their designed coordinate. For the first 42 mars days, zhurong traveled 236m.
That's why the rover landing happened 3 months after the probe reached Mars orbit. They spent that time to do all the reconnaissance work to prepare the landing.
Also this is the reason this mission is considered to be a great success, it shows their ability to landing on a totally unknown planet.
Once you've got that down pat, it's not that different to land one on Mars, especially since the Chinese rover was small enough not to require the elaborate skyhook approach.
Also, NASA is legally prohibited from cooperating with China on anything space-related.
Of course it’s different. You need to know how to make solar panels so that it will work on Mars. It’s different than those you would need for the moon. It would have to work through the dust storms.
The equipment would need to be rated differently. How the signal is sent from the rover to the orbiter would be different, etc. There’s a lot of knowledge that you would need to build up about Mars and having probes on Mars and the logistics of sending data to and from Earth via orbiter that you would need before jumping all the way to sending a large expensive rover to Mars.
That’s interesting about NASA not being allowed to share data. I really wonder how China was able to leap to sending a rover without lots of investment in understanding everything else about it.
Many of the design outputs of the NASA rover programs are public domain. For example, the peak solar panel rating of the MER (Opportunity and Spirit) is published, the size of the panels are known (or can easily by estimated), the power needed to drive the rovers around is published, the weight of the rover is published, the size of wheels can be easily estimated (or is published).
The logistics of sending data back can be reasonably considered to be a challenge that could be solved on the first try. The first space probe that NASA managed to actually get to Mars (Mariner) worked. The first landers that NASA managed to get to Mars (Viking) worked.
The proportion of Chinese stem graduates who aren’t simply copying their way around and are gifted enough to run these programs is likely about the same as the proportion anywhere else. Chinese people are no more or less intelligent than anyone else.
In my country, and I guess otherd in western Europe, we often fail to appreciate the sheer power of those "other" countries such as Russia or China. Many are still stuck in the colonialist vision of things where Europe and US were vastly superior. This is not true anymore. And as you point out, intelligence is uniformly distributed.
Days when Russia could send problems to Mars are long over, so with regards to Russia reality ironically corrected itself to match the US expectations.
Well, I must admit picking Russia was a bit far fetched :-) However, I have the feeling Russia is still a strong player on the geopolitical level (see Syria, Ukraine -- although I'm sure civilian casualties say otherwise).
Not supporting OPs assertion, but. Even with same proportion they will have huge advantage in absolute nos. Also society and government are lot different, changing the way and proportion of people persevere for a particular career option.
let's put ideology aside. It's quite interesting to watch different societies, governance, cultures evolving, cooperating,competing among each other. Eastern world is more likely have low entropy societies while Western have high entropy societies.
Both have strength and weakness. Low entropy societies are more efficient, extremely good at building physical things. But tend to have less varieties. High societies are more chaotic, but also more innovative, more productive in spiritual domain. Not only in technologies but also arts ,etc.
It would be ideal that both societies can cooperate and share the benefits leveraging advantages of both worlds. But in reality it's quite complex and not going to a good direction in short term
This seems like a "just so" statement. Fifty years ago people would say that Western societies are more efficient and better at building physical things.
So I don't really see it. I don't think Western societies are necessarily always going to be better at technology and I think you really, really underestimate the chaos and varieties of many non-Western societies. In many ways the West is quite low-entropy.
On HN it seems like there is a huge anti-US/sinophile presence which seeks to elevate any achievement, no matter how minor or retread, as if it were some major accomplishment done in spite of insurmountable purposeful opposition by the evil colonial empire building westerners. When even the slightest accomplishment is so outlandishly propagandized it becomes hard to view actual ones in their proper light. Especially when it’s unclear whether they’re “standing on shoulders” or simply trying to pass the shoulders off as their own.
Don't make the mistake thinking that this happened without "lots of investment". The Chinese space program is massive and has been running for decades.
Does the Martian atmosphere filter out certain frequencies of light? And how does it compare against the frequencies that their rover solar panel is sensitive to? Or is their atmosphere thin enough such that UV light gets through? Can they make use of that?
Lots of questions just about their solar panels and what would be the most effective chemicals to make their solar panels out of to maximize their output.
They have no probes previously on the surface of Mars. How would they know how to make their solar panels to be the most efficient without data? Did they just guess? Did NASA share that information? Or is that secret information that NASA kept quiet and Chinese spies stole that information?
All three possibilities could have occurred but I really doubt that China would just guess and then spend billions of dollars to send a probe without knowing if it would work.
Composition of the atmosphere and knowing what frequencies of light make it all the way to the ground is different. There’s so much dust in the air that it might reflect different frequencies depending on where you are. That’s why having a cheaper probe on the ground that measures this makes it a better chance of getting it right for more expensive probes. But they don’t have those initial probes.
My point is China has no probes on Mars unless they have secret ones. They can GUESS what would be best optional frequencies to tune their solar panels for but my point is that they are spending billions of dollars. Do they really want to rely on data they didn’t retrieve themselves? That seems like an odd thing to take a risk on. Better to either work together with nasa since they have the expertise. Hence I’m curious what the relationship is between China and nasa for this project and if it was an open one or if they got the data some other way.
Of course it's different, but you're still sending a probe to a celestial body, so things like building the rocket, designing radiation-hardened hardware, space communications, launching on a desired trajectory, automated landing with retro-propulsion etc are all similar and needed for both. Basically, if you're going to practice the Moon is the place to do it, and that's why the US, Soviet, Chinese and now Indian space programs are all following the same basic game plan.
> How did China know how to make their rover without sending a bunch of probes onto Mars?
Why would they need probes? The Mars atmospheric composition isn't exactly classified information, they know it's a solid surface. The rest is just math and some very complex engineering.
