27 ms·

Julia and the satellite Amazonia-1 (2020)

185 points by montalbano 6y ago

montalbano 6y ago
I also found a press release on the Julia Computing website: https://juliacomputing.com/case-studies/BrazilNationalinstituteforspaceResearch/ https://juliacomputing.com/case-studies/BrazilNationalinstit... But the forum link above seems more informative and the software architect has answered questions within the thread.
myth2018 6y ago
Ronan's blog. Interesting stuff: https://www.ronanarraes.com/main/ https://www.ronanarraes.com/main/
vslira 6y ago
Between this, BNDES (Development Bank) and Bacen (Central Bank, its "Fed"), it seems like Brazil's public service is a Julia hotspot.
- haolez 6y ago
  Brazilian institutions used to love FORTRAN and Matlab. Maybe Julia was more familiar to their teams somehow.
  - selimthegrim 6y ago
    Did Lua ever have a corresponding long march through the institutions?
    - haolez 6y ago
      I don't think so. For example: Lua was supposed to be the official language for interactive broadcast TV apps in the early 2000s, but it lost to Java due to IT consulting firms pressure.
- boibombeiro 6y ago
  The Brazilian academics favors open source over commercial software (the most well ranked universities in the country are free, and many student cant't afford to pay license fee). So it doesn't come as surprise egresees uses Julia, R over the paid counterpart.
- elzbardico 6y ago
  Not really. julia is niche at the best in Brazil. Python largely dominates the scene
montalbano 6y ago
I didn't put a (2020) in the submission title as the post was only created 6 days ago. Did I miss something here? I'm sure it was editorialised for a reason but I can't figure it out, sorry if I'm being stupid.
- soneca 6y ago
  And the post couldn’t be older since it has a photo from a satellite that was launched this year. My guess it is some automated task that got confused because the post is in a forum, not a regular blog post with a publishing date.
- themulticaster 6y ago
  I just created an account to tell you my guess: The timeline to the right of the post shows "Mar 20", for the 20th of March (2021). I think some moderator misunderstood that as March of 2020 and changed the title.
  - 3JPLW 6y ago
    As an administrator at Julia's discourse, I'd be really curious if this was the reason. Discourse's default "short date" format is super problematic. By default, they display something from 5 days ago as `Mar 20` and something from a year ago as `Mar '20`. We've changed that to have the year+ old posts display as `Mar 2020`, but maybe we should also change the recent display to be something different; maybe `20 Mar`? The UI doesn't give us too much space, unfortunately.
    - neolog 6y ago
      > The UI doesn't give us too much space, unfortunately. I don't see where it's cramped, there's a lot of room on my screen. Another option is "June 20^{th}"
      - 3JPLW 6y ago
        That same format string is used in multiple places, and unfortunately I don't think the text engine they expose to us is smart enough to do the ordinal 1st 2nd 3rd thing. Edit: oh, we can do that. Changed experimentally.
sremani 6y ago
Amazonia-1 was put in orbit by PSLV launch from SHAR this year (2021). The annotation (2020) is wrong. https://www.space.com/india-launches-amazonia-1-satellite-18-others https://www.space.com/india-launches-amazonia-1-satellite-18...
- montalbano 6y ago
  See my comment above. I'm not sure why it was changed but hopefully one of the mods can change it back.
thatcherc 6y ago
SatelliteToolbox.jl[0] (one of the packages developed by the post author) is one of my most-used Julia packages! It's great for (among many other things) working with TLE orbits and presents a really nice interface for converting between all the different Earth-fixed and Earth-centered-inertial frames, which is generally a huge hassle. Ronan has also been very friendly to PRs on Github which is always nice. Awesome to see this mission come together! [0] - https://github.com/JuliaSpace/SatelliteToolbox.jl https://github.com/JuliaSpace/SatelliteToolbox.jl
muskox2 6y ago
Very cool thread, and encouraging to see that they could open-source a good bit of the satellite code.
junippor 6y ago
This post illustrates one of the reasons why I love Julia. When talking to Python colleagues about Julia one response is "well, but I don't really care about performance _that_ much". The thing about Julia is that you can code without caring about performance (and the performance will be Python-like). If later on it turns out that you DO care, you CAN optimize it. With Python you don't have that option, as in Python "optimizing" means using cython/numba over numpy arrays, and all the limitations inherent to that approach. This is obviously good, and I'm not even sure what the trade-off is. What am I losing?
- bb1234 6y ago
  You said "The thing about Julia is that you can code without caring about performance (and the performance will be Python-like)." This is not my experience. Even if you code without caring about performance it is way faster than Python. Also, it is not any harder to code in than Python. It is as high level if not more.
  - junippor 6y ago
    Yeah, that's often the case but I wanted to make a conservative claim. Two personal examples where Julia turns out to be much much faster than Python without me having to do anything but the most naive implementation: - order of 10 float arrays with order of 1_000_000 elements each. Broadcasting an element-wise function in Julia or just doing a for-loop in Julia is way way faster than a pandas operation like col1 * col2 + col3 etc. - the first time I tried one of Julia's optimizers (I think Optim.jl) it took 1ms on my problem. Sci-kit took 200ms. That's crazy.
  - oxinabox 6y ago
    > This is not my experience. Even if you code without caring about performance it is way faster than Python. It is very usecase dependant. If your Python code is writing lots of loops and scalar processing then naive julia code will trash it. but if it is basically spending all its time in numpy/BLAS routines then they will be comparable. and Julia will looks like its not worth it, since compile time makes it overall slower etc. > Also, it is not any harder to code in than Python. If you already know Python then it is easier to use what you know. Furthemore, if you already know Python (or even more so Matlab) it can cause some stumbling blocks. Some idiomatic code in other languages, (like writing everything as big array operations), is unidiomatic in julia (since it causes a lot of allocations tht you don't need)
ChrisRackauckas 6y ago
I'm glad to see some of Ronan's work get a spotlight. He was one of the early DifferentialEquations.jl users and discussions with him + bug reports really helped guide the SciML project in the right direction. He's one of those Julia community members that really makes OSS development a fantastic experience. You can trace a lot of the 2016-2017 design choices around callbacks to helping his satellite control use cases. Now, that satellite is up there. It's a really nice and personal example of how this "Julia Generation 3" community has grown and matured over the last half decade.
airstrike 6y ago
Off-topic, but I'm always amazed at how massive Sao Paulo is. I remember visiting a museum there - I think it was the MASP - and there was this sprawling installation of a satellite view of the city that you could walk over. I walked, and walked, and walked and it felt like I could never reach the edge

185 points by montalbano 6y ago

I also found a press release on the Julia Computing website: https://juliacomputing.com/case-studies/BrazilNationalinstituteforspaceResearch/ https://juliacomputing.com/case-studies/BrazilNationalinstit... But the forum link above seems more informative and the software architect has answered questions within the thread.

myth2018 6y ago

Ronan's blog. Interesting stuff: https://www.ronanarraes.com/main/ https://www.ronanarraes.com/main/

vslira 6y ago

Between this, BNDES (Development Bank) and Bacen (Central Bank, its "Fed"), it seems like Brazil's public service is a Julia hotspot.

haolez 6y ago
Brazilian institutions used to love FORTRAN and Matlab. Maybe Julia was more familiar to their teams somehow.
- selimthegrim 6y ago
  Did Lua ever have a corresponding long march through the institutions?
  - haolez 6y ago
    I don't think so. For example: Lua was supposed to be the official language for interactive broadcast TV apps in the early 2000s, but it lost to Java due to IT consulting firms pressure.
boibombeiro 6y ago
The Brazilian academics favors open source over commercial software (the most well ranked universities in the country are free, and many student cant't afford to pay license fee). So it doesn't come as surprise egresees uses Julia, R over the paid counterpart.
elzbardico 6y ago
Not really. julia is niche at the best in Brazil. Python largely dominates the scene

montalbano 6y ago

I didn't put a (2020) in the submission title as the post was only created 6 days ago. Did I miss something here? I'm sure it was editorialised for a reason but I can't figure it out, sorry if I'm being stupid.

soneca 6y ago
And the post couldn’t be older since it has a photo from a satellite that was launched this year. My guess it is some automated task that got confused because the post is in a forum, not a regular blog post with a publishing date.
themulticaster 6y ago
I just created an account to tell you my guess: The timeline to the right of the post shows "Mar 20", for the 20th of March (2021). I think some moderator misunderstood that as March of 2020 and changed the title.
- 3JPLW 6y ago
  As an administrator at Julia's discourse, I'd be really curious if this was the reason. Discourse's default "short date" format is super problematic. By default, they display something from 5 days ago as `Mar 20` and something from a year ago as `Mar '20`. We've changed that to have the year+ old posts display as `Mar 2020`, but maybe we should also change the recent display to be something different; maybe `20 Mar`? The UI doesn't give us too much space, unfortunately.
  - neolog 6y ago
    > The UI doesn't give us too much space, unfortunately. I don't see where it's cramped, there's a lot of room on my screen. Another option is "June 20^{th}"
    - 3JPLW 6y ago
      That same format string is used in multiple places, and unfortunately I don't think the text engine they expose to us is smart enough to do the ordinal 1st 2nd 3rd thing. Edit: oh, we can do that. Changed experimentally.

sremani 6y ago

Amazonia-1 was put in orbit by PSLV launch from SHAR this year (2021). The annotation (2020) is wrong. https://www.space.com/india-launches-amazonia-1-satellite-18-others https://www.space.com/india-launches-amazonia-1-satellite-18...

montalbano 6y ago
See my comment above. I'm not sure why it was changed but hopefully one of the mods can change it back.

thatcherc 6y ago

SatelliteToolbox.jl[0] (one of the packages developed by the post author) is one of my most-used Julia packages! It's great for (among many other things) working with TLE orbits and presents a really nice interface for converting between all the different Earth-fixed and Earth-centered-inertial frames, which is generally a huge hassle. Ronan has also been very friendly to PRs on Github which is always nice. Awesome to see this mission come together! [0] - https://github.com/JuliaSpace/SatelliteToolbox.jl https://github.com/JuliaSpace/SatelliteToolbox.jl

muskox2 6y ago

Very cool thread, and encouraging to see that they could open-source a good bit of the satellite code.

junippor 6y ago

This post illustrates one of the reasons why I love Julia. When talking to Python colleagues about Julia one response is "well, but I don't really care about performance _that_ much". The thing about Julia is that you can code without caring about performance (and the performance will be Python-like). If later on it turns out that you DO care, you CAN optimize it. With Python you don't have that option, as in Python "optimizing" means using cython/numba over numpy arrays, and all the limitations inherent to that approach. This is obviously good, and I'm not even sure what the trade-off is. What am I losing?

bb1234 6y ago
You said "The thing about Julia is that you can code without caring about performance (and the performance will be Python-like)." This is not my experience. Even if you code without caring about performance it is way faster than Python. Also, it is not any harder to code in than Python. It is as high level if not more.
- junippor 6y ago
  Yeah, that's often the case but I wanted to make a conservative claim. Two personal examples where Julia turns out to be much much faster than Python without me having to do anything but the most naive implementation: - order of 10 float arrays with order of 1_000_000 elements each. Broadcasting an element-wise function in Julia or just doing a for-loop in Julia is way way faster than a pandas operation like col1 * col2 + col3 etc. - the first time I tried one of Julia's optimizers (I think Optim.jl) it took 1ms on my problem. Sci-kit took 200ms. That's crazy.
- oxinabox 6y ago
  > This is not my experience. Even if you code without caring about performance it is way faster than Python. It is very usecase dependant. If your Python code is writing lots of loops and scalar processing then naive julia code will trash it. but if it is basically spending all its time in numpy/BLAS routines then they will be comparable. and Julia will looks like its not worth it, since compile time makes it overall slower etc. > Also, it is not any harder to code in than Python. If you already know Python then it is easier to use what you know. Furthemore, if you already know Python (or even more so Matlab) it can cause some stumbling blocks. Some idiomatic code in other languages, (like writing everything as big array operations), is unidiomatic in julia (since it causes a lot of allocations tht you don't need)

ChrisRackauckas 6y ago

I'm glad to see some of Ronan's work get a spotlight. He was one of the early DifferentialEquations.jl users and discussions with him + bug reports really helped guide the SciML project in the right direction. He's one of those Julia community members that really makes OSS development a fantastic experience. You can trace a lot of the 2016-2017 design choices around callbacks to helping his satellite control use cases. Now, that satellite is up there. It's a really nice and personal example of how this "Julia Generation 3" community has grown and matured over the last half decade.

airstrike 6y ago

Off-topic, but I'm always amazed at how massive Sao Paulo is. I remember visiting a museum there - I think it was the MASP - and there was this sprawling installation of a satellite view of the city that you could walk over. I walked, and walked, and walked and it felt like I could never reach the edge