China on Mars: Zhurong rover returns first pictures | Hacker News Reader

China on Mars: Zhurong rover returns first pictures

bbc.com

243 pointsleemailll66 comments

It's an interesting design, in someways the ramp is a deceptively simple concept but I'm not sure if it's safer than the US approach.

Some other neat things are:

Solar panels, they are a specially designed to electrically repel Martian dust, in theory there should be a decent power gain from this and it will likely be used in future missions. While other rovers fortuitously found solar was self cleaning on Mars, power is still a knife-edge engineering problem for rovers.

Ground penetrating radar, can see down 100m, a lot further than anyone else has ever investigated, should yield some interesting data. Like most other missions they are very interested in prior and current water on the planet.

Coverage, they are planning a few hundred metres over 3 months, the rover itself can do 200m in a day though if needed, very unlikely that will happen but it is in a flat area of Mars. The landing zone was so huge that there'll be some tough choices about what is the most productive area to explore for planetary science.

The speed of entry, Zhurong came in at about half the speed of Perseverance, this makes life a lot easier. It takes a lot longer to bleed off that velocity in orbit but seems like other nations attempting a landing will follow this path.

I'd be interested to know about their uplink, remember hearing they might be using an ESA orbiter but not sure about that, the orbiter they have is not that great for a connection due to it's altitude.

Technical info is surprisingly hard to find, even in publications like nature or science mags normally focused more on the details.

The rocket backpack seems like it would allow you to land more weight than the lander an ramp method because you don't have a much superfluous structure on the rocket lander section of the craft. Zhurong is only about as big as Spirit and Opportunity that the US landed back in 2003 using big airbags, larger rovers can't do that so you get into more complex things like the sky crane.

The main problem with Zhurong is they brought their orbiter along with them. Since they can only launch 6000kg to trans-martian orbit, packaging the rover and orbiter together limits your rover.

NASA launched its orbiters on separate missions, which means both the Orbiter and Rovers can be bigger without needing a ginormous launcher.

I was mostly thinking about the amount of weight that the Zhurong style lander would be able to land vs the Curiosity/Perseverance skycrane style of lander used by NASA. It's quite complex but it seems like it allows more of the mass to be in the rover vs the rover just because the Zhurong lander needs to carry the weight of the rover on top of it where the skycrane doesn't.

I don't think the technical data being hard to find is that surprising. China has a pattern of not talking about their space missions unless they go well. Since they control their press the party only ever gets good press. It's also worth noting that the CNSA is not a civilian agency like NASA or the ESA. It's a military agency and treats programs as if they're secret military projects.

Here's a video from Chinese TV in Feb before the landing that someone else posted in this thread: https://www.youtube.com/watch?v=rBhVaihkDvc

I realize it doesn't have English subtitles, so I'll summarize some highlights of what's in there:

* interviews with scientists and engineers working on the project

* trajectory of the spacecraft and lots of talk about the challenges of reducing velocity for landing

* historical overview and context for why Mars exploration is important for science

* what to expect in the future landing and when it'll happen

It's pretty similar to video programs that NASA produces. Not sure what information you're expecting that isn't out there, but I think you're attributing to secrecy what is more easily attributable to people not translating open public reports into English.

Here's a technical review of the (engineering, not science) imaging system for Perseverance, published in November 2000 before a touchdown in February 2021:

https://link.springer.com/article/10.1007/s11214-020-00765-9

Here's the process for how the landing site was selected:

https://mars.nasa.gov/mars2020/mission/science/for-scientist...

I think this is more open than the Zhurong information has been, but I'd be happy to learn more.

CNSA is under MIIT (Ministry of Industry and Information Technology) not PLA.

> CNSA is not a cilivllian agency

Look at Wikipedia: CNSA is under the jurisdiction Ministry of Industry and Information Technology (工信部）, which itself is a civilian department, at least not less so than US department of energy.

What's the proof for your claim that CNSA is not a civilian agency?

I am no expert in china, I don't know what exactly it means. But if my country had a "State Administration for Science, Technology and Industry for National Defense", and the national space adminstration reported to them, i would assume the national defense was military.

According to https://en.wikipedia.org/wiki/State_Administration_for_Scien...

"State Administration for Science, Technology and Industry for National Defense" is a civilian ministry within the State Council of the People's Republic of China and is a subordinate agency of the Chinese Ministry of Industry and Information Technology and the superseding agency of the Commission for Science, Technology and Industry for National Defense (COSTIND).

You might as well think Ministry of Industry and Information Technology is in charge of civilian and military application of relevant tech in manufacturing and information tech. Just like DoE also manages nuclear weapons.

The DOE/NNSA has federal responsibility for the design, testing and production of all nuclear weapons. According to https://en.wikipedia.org/wiki/United_States_Department_of_En...

I am unhappy about the parent, is that people are commenting things without sensible realization of their own limitations. I frequent here, is because of people are far more sensible about their limitations on almost all topics.

But that sensibility is non-surprisingly low in China-related topics.

>China has a pattern of not talking about their space missions unless they go well

Not only space. This is the reason it always feels like the west is collapsing while Chinese hegemony is inevitable. Western news outlets publish hyper-critical editorials about western governments that wouldn't be allowed on state run media in the east.

Go read the book manufacturing consent.

Case in point, would that book have been published if all publishers were ideologically controlled by the state?

The whole point of the book is that it's not necessary for publishers to be controlled by the state for the state to control public opinion.

So, go read the book.

This is totally simplistic. If you think western journalists are incentivised to criticize basic societal norms and systemic problems, I have a bridge to sell you. I'm also not sure where you're getting these 'hyper-critical' editorials from - where I come from, nearly 150 thousand people just died in a pandemic, and the media has barely said a critical word.

Obviously, in China, they are allowed to criticize even less, but westerners do not read chinese news.

What's more, nor does anybody else.

So the image of China doing very well is not for a lack of bad press. If you read publications about China over the last decade or so, it's a constant slew of doomsaying, and negativity, mostly about problems that turned out to be very surmountable or insubstantial.

The image of China becoming more and more hegemonic is simple: look at their economic growth. Look at the size of the nation. Look at their intellectual culture. China being a very powerful country is a return to a historical norm, and is a totally reasonable development given how big their population is, how skilled it is, and its values.

Meanwhile, the west is seen as falling apart because it is having a massive identity crisis which involved things like the leader of the free world bragging about how big his nukes were on Twitter.

I'm not frankly particularly enthusiastic about China as a world power - I'm not a fan of confucianism, for example, and CCP spokespeople talk like politicians from dystopian sci-fi, but I think it's profoundly wrong to think China is deceiving the world with its masterful press controls. Far from it - the direct censorship and press controls are very blunt mechanisms most states have given up on because they don't work and if you're good at media, you don't need them anyway.

China was never really a world power, even at its height. Look back at Western history: Alexander the Great, the Roman Empire, the British Empire, or the Mongols, or further back, the Xiongnu. Han China mostly stayed confined to its own self imposed borders, with the exception of the acquisition of Xinjiang and the Tibetan plateau, and some voyages by Zheng He.

I guess what I'm saying is, if China becomes a hegemonic power, it won't be militarily, it'll be economically, sort of like monopolies/oligopolies today, and those kinds of powers can be resisted much more easily by soft power methods.

The economic growth argument fails to impress it. Every nation that goes through an agrarian->industrial conversion experiences huge economic growth until they transition to a developed service sector economy.

Much is made about Chinese infrastructure building, but did you ever look at what was done by FDR under the New Deal? 1 million kilometers of roads built. 10,000 bridges. 40,000 schools. etc. The Tennessee Valley Authority built tens of thousands of miles of electric grid. Or take progress in the Space Program of China. It looks impressive, but Von Braun founded the US rocket program in 1945, and NASA was founded in 1958. 11 years later, there were men standing on the moon.

Things only look fast now, because developed Western economies have settled into long term 2-3% service oriented economy growth. With China's declining birth rate, rising cost of living and wages, it too will experience a slowdown.

> It's also worth noting that the CNSA is not a civilian agency like NASA or the ESA

Given how many classified Shuttle missions[1] took place over the decades it was in service, and how the Hubble Space Telescope was likely a clone of a spy satellite, I don't think it's fair to say that NASA is entirely a civilian agency.

[1] https://www.space.com/34522-secret-shuttle-missions.html

> It's an interesting design, in som eways the ramp is a deceptively simple concept but I'm not sure if it's safer than the US approach.

It's the 'standard' way as far as I know (see Path Finder/Sojourner for instance).

The 'sky crane' system used by the US is fairly new and, I guess, much more complex to pull off and more expensive. I think it was developed partly because the payload had become too big/heavy for the previous airbag system.

Do you have a reference for the electrically-repelling solar panels? They sound fascinating.

Not original commenter, but here are some relevant papers that should have publicly available pdfs if you search for them on Google Scholar:

Landis, G. A. (1998). Mars dust-removal technology. Journal of Propulsion and Power, 14(1), 126-128.

Kawamoto, H., & Shibata, T. (2015). Electrostatic cleaning system for removal of sand from solar panels. Journal of Electrostatics, 73, 65-70.

Saravanan, V. S., & Darvekar, S. K. (2018). Solar Photovoltaic panels cleaning methods: A Review. Int. J. Pure Appl. Math, 118, 1-17.

Reading the last names of the authors of these publications is refreshing, particularly in contrast to the often nationalistic comments that have peppered discussion of this rover.

Maybe the future is brighter than we think!

Care to elaborate why you think the comments on this rover are nationalistic? Or, do you feel the same way about comments regarding NASA or JAXA achievements?

Disclaimer: I'm a China/Chinese national.

I think they were referring to earlier nationalistic dismissals/unfounded skepticism.

I haven't been able to find any evidence supporting this claim.

https://www.nytimes.com/2021/05/14/science/china-mars.html says, for example:

> Days after the touchdown, the rover will roll off the lander. Like Spirit and Opportunity, Zhurong will be powered by solar panels, which are retractable so that it can periodically shake off any accumulated dust.

I'd love to learn more.

The ramp approach was used by the 1997 Sojourner rover: https://flickr.com/photos/rhubarble/268583624

> It's an interesting design, in someways the ramp is a deceptively simple concept but I'm not sure if it's safer than the US approach.

I think its closer to the Sojourner rover approach. It works fine for lower weight rovers but at higher weight you need a rocketpack or something.

Although the US rover program has made Mars look easy, it's been fiendishly failure prone for other space agencys

Outside of one Russian lander working for 120 seconds after touchdown before failing, no nation outside the US has ever gotten a lander to work on Mars before.

Have a look at the list of mars missions and see just how many failures there are:

https://en.wikipedia.org/wiki/List_of_missions_to_Mars

joint effort with the the ESA (European Space Agency), let's not forget that

http://www.esa.int/ESA_Multimedia/Images/2020/04/Perseveranc...

Good for them. It's great to see space exploration picking up outside of our efforts in the US. I would be great if we could cooperate more upfront, but the more people around the world that know how to land a payload on another planet the better. That kind of applied science and engineering is really valuable.

competition is great, but it's a shame that space became primarily a warfare competition(chinese space programm is 100% army project)

Hopefully there is a chance, space will become a space for commercial and other civil kind of competition, when we start to mine asteroids

What is the map projection called in that map from NASA?

It basically looks like equirectangular and modified with pointy poles.

https://en.wikipedia.org/wiki/Equirectangular_projection

Maybe it is just regular equirectangular but the lines are drawn weird.

It's a completely standard Cartesian projection (x = longitude, y = latitude), but with nonsense graticules plotted on top. I think BBC took a NASA image of Mars and added their own graticules and landing-site labels. Compare the BBC image with these two NASA images:

* BBC: https://ichef.bbci.co.uk/news/976/cpsprodpb/825B/production/...

* NASA base map of Mars: https://astrobiology.nasa.gov/uploads/filer_public_thumbnail...

* NASA landing sites: https://mars.nasa.gov/resources/24729/map-of-nasas-mars-land...

It looks like the equirectangular Mars projection. Details can be found on the HiRISE or THEMIS sites.

Has there been any discussion on "nations" on mars? I just always assumed Mars would have colonies like ISS spread around.

I wonder if anyone is planning on marking territory

The Outer Space Treaty prohibits the claiming of territory in space or on other planetary bodies. This treaty is signed by all of the major spacefaring states. If states begin to extract resources or establish permanent habitation beyond scientific expeditions such as the ISS, the terms of this treaty will not be tenable. There is no magic solution to prevent states from being self-interested and claiming resources for themselves, but hopefully the resolution will be a new treaty which provides a framework for peaceful, fair, and sustainable development of space. Some self-enrichment can be allowed while also ensuring that some of the benefits flow to all of humanity. The alternative, if no such agreement can be reached between the spacefaring powers, is a free-for-all in which states withdraw from the OST and do whatever they want. This seems likely to lead to monopolization of the solar system’s resources by a few states. It also seems likely to lead to confrontation between the spacefaring powers.

they may need a treaty to resolve issues between private companies as well and not only nations give we are seeing more private enterprise enter spa(ce)tial frontier.

Space treaties (like sea treaties) consider states to be the parties to the treaty, and states are responsible for ensuring compliance from their private companies. Private companies are not directly party to the treaty. So, for example, if a treaty requires the United States to do something (such as avoid using a certain type of resource), the United States is responsible for making US companies (like SpaceX or ULA or whoever) comply. Again, this comes from the sea law tradition: private ships at sea must be registered in some state, which is responsible for ensuring compliance with the international laws to which that state is party.

I believe the current treaties do allow for extracting resources, but as you say, you can't stake claims. What this means, as far as I understand it, is that if you take a resource it's yours but once you leave the extraction site such as an asteroid, someone else can come along and take what's left. You can't claim it's yours because you visited it.

I think this is a reasonable approach and I doubt it would be much of a problem in practice. While you are physically present or have assets in place anyone else interfering with you would be infringing on your property - equipment, personnel, etc. That should be enough to establish functioning regulations, although there will be a lot fo details to work out.

What is "leave" in this context? If I leave my robominers or rovers somewhere do I still own them? If they aren't operational? If they are operational but not operating?

I thought this looked familiar https://youtu.be/0L01FxuRBZY?t=11

Is there a lot of cooperation between the NASA rover team and the Chinese?

"Since 2011, the United States National Aeronautics and Space Administration (NASA) has excluded the Chinese government and China-affiliated organisations from its activities, including using funds to host Chinese visitors at NASA facilities."

No. Many aspect of NASA's work is highly controlled under ITAR.

I used to have to be debriefed after ANY foreign travel because other people in my lab used image processing software that was covered under ITAR...

Does anybody know how these are reported in chinese media? NASA makes a huge effort to publish their stuff in the western world and you don't hear much about china. Is it the opposite from inside China?

They were very low key about it right up until it landed, then once they were sure it was ok they hit the domestic media pretty hard. Scenes of mission controllers hugging (somewhat awkwardly), group shots of the mission team with dramatic backdrop images, etc.

I can understand they were concerned about the risk of a problem, landing anything on Mars is hard. ESA has failed twice now, and historically about half of all missions to Mars have crapped out. It's a genuinely impressive achievement, for all the sour grapes about stealing US tech, actually implementing this stuff and following through like this is no cakewalk.

I suspect this will be pointed to as the moment China pulled ahead of Russia in space technology. Yes Russia has more achievements under it's belt, but most of that was over a generation ago. In terms of current capabilities I think this is really significant.

I don't think you can get an unbiased reply on this topic on HN unfortunately (or any other SoMe site). You can look at CNSA.gov.cn yourself though and make up your own mind :)

English site: http://www.cnsa.gov.cn/english/index.html

> (or any other SoMe site)

What does SoMe mean?

My guess : Social Media.

I never heard this either. Please just use social media

> I never heard this either. Please just use social media

I agree. It's also impossible to Google, since that acronym is also a common word.

Sorry about that. Social media :)

Oh no problem. I thought it was a place name, like SoCal for Southern California or Soho.

Here are a few videos from Chinese media, well before the landing. You can judge for yourself:

* January 2021: https://youtu.be/HaZOfZYOLgU

* February 2021: https://youtu.be/rBhVaihkDvc

My dad sends me articles about it on WeChat all the time, but I have difficulty reading it since my Chinese reading comprehension is barely at a 3rd grade level. They do make a big deal about it and it gets lots of coverage.

There are a lot of posts indeed circulating on my Wechat timeline so it is quite well covered.

Out of interest what is 3rd grade level Chinese reading? I'm curious to know what kind of grading is that?

I'm literate enough to read the entertainment section of a newspaper, and get a perfect score on the SAT 2 Chinese language test in the US. Technically, I wouldn't really be considered literate for an adult though.

When I came to the US at 4.5 years old, my mom brought with us some textbooks, enough for kindergarten through 3rd grade. I'm mostly self taught with help from my mom.

I more or less speak like an adult, but if I'm asked to read anything more complex (e.g., bank documents, geopolitics news), I'm completely lost.

Interesting. I can never imagine a grading system for chinese as a native speaker so got intrigued. Having done language tests for English when I was a student but can't imagine the other way around. Will look up for more. Thanks

There is a YouTube channel from New China News Agency. It's the Reuters in China. You can find quite a few videos on the Mars rover.

https://www.youtube.com/c/ChinaViewTV/videos

As a Chinese I know that the government doesn't publicize such things very often, even in Chinese. Medias are not really professional enough to do these kinds of reports either. Most reporters simply do not have enough science and tech background to even ask good questions. If you know Chinese and listen to the live reports you can feel it.

Things might turn around for the next decade when more young people who are motivated by these missions get into the fields (both R&D and media). But again I won't expect a lot of English reports. There will be some in the English channels such as CGTV.

The launch of the Tianhe core module was live streamed on Tiktok and possibly other outlets. Not sure about this one though.

I expect this post won't garner the same attention here. I wonder why that might be.

While I know what you mean (and it's true to some extent), I think the media strategy and of course lang sphere barrier are factors. With the American Mars landing it's a big live event with the landing time known down to the second in advance, designed to generate a lot of momentous excitement. The Chinese space programme tends to release information more sparingly and after the fact.

I'd actually love to know more about this from a good English source (unfortunately I haven't taken the time to study Mandarin), really. Especially the engineering - it's been a while since we had two distinct tech stacks on the Red Planet, it'd be cool to compare and contrast.

The official site of CNSA is available in English:

http://www.cnsa.gov.cn/english/index.html

Part of that is because a lot of space activity in the West is competing for public funding and so you get a huge amount of publicity around any event to ensure that the public sees where its money goes. A plan economy doesn't really have that problem, publicity is an afterthought and if it has value that is more on the international stage (so when it is successful) then nationally, where it is welcome but not a necessity.

So that's why you'll see the accent on success rather than on activity.

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