Category Archives: X3Prospero

technical X3Prospero

Has anyone seen my satellite?

Sultans of Ping FC - Where me Jumper

As someone who is prone to losing jumpers and can never remember where i put my keys it might seem a bit ambitious to try and find a satellite, but I'm going to try.

Here's the plan, in fact here are both the plans.  in fact here are all the plans mostly.  When I first thought of this project, after coming up with this idea of making Prospero X3 tweet my next thought was is it actually possible?  The answer to after a quick search on the internet  was yes. Using or other similar sites its easy to find the position of pretty much any satellite that is in orbit around the earth.

For a few minutes my plan was to use that or a similar website, scrape the data from it and feed that to a twitter bot. I couldn't  write a twitter bot yet but twitter bots exist so writing one probably wasn't going to be that hard.  All in all I figured that scraping the data and writing the twitter bot could be done in a weekend or two. i could put my feet up, have a cup of coffee and cake, look back  at  the work i'd done then move on to the next thing.

Then it hit me. Prospero X3 was as far as I was aware a dead satellite, it wasn't transmitting it position back continuously,  the display was being updated  in real time so it wasn't done through observation.  It must be possible to work out where satellites are in space,that is cool and  this is when I started falling down the rabbit hole.

So far I've discovered Two Line Elements, Kepler's Laws of planetary motion, SGP4, Lagrange points and even how Astronauts go to the toilet.  It started off with buying Dr Lucy Rodgers book Its Only Rocket Science   and when I wanted to get a bit more technical Fundamentals of Astrodynamics and Applications  .

I have realised a couple of things. The work has already been done to produce the algorithms needed to work out where  satellites are, its taken may years of correcting and checking these, I was never going to be able  do this again from scratch and there was no need. , but I did want to do something more than just take the data and use it, but wasn't sure what.

The twitter bot in place, just waiting to be fed some data to tweet.  I can find the position of the satellite at any given time using the Python Implementation of the SGP4 Algorithm. The satellite position is given as a Vector  so doesn't make much sense in that form, the next job is to turn that into a Latitude and Longitude position on the surface Earth. Have been working on that today and its coming along nicely,lots of Greek letters to remember and it turns out there are multiple Latitudes .  The Maths isn't horrendously complicated, there are new symbols and words to learn but its mainly Vectors, Matrices and geometry, nothing too scary.  I Keep wanting to say its not rocket Science but actually it is which is pretty cool.

So feeding the twitter bot data from the python SGP4 script is easy and I could finish the project at that but I have decided that it would be interesting to have the entire project in nodejs which the twitter bot is written in.   Writing the  SGP4 Algorithm in nodejs  is the 'more' thing i mentioned earlier.

I am currently working through the Python Script nodejs'ing it .  I'm not doing a straight conversion, it is being written in the asynchronous nodejs style using callbacks rather than return of functions.  I'm not sure if this is the best way to do it but I am learning, when its finished that is when i'll be in a place to judge.  I'm also changing the variable names from there one and two letters into much more meaningful ones.  Again not sure if  that is the thing to do but its my project and it pains me to use single letter variable names so changing them.

Having Prospero X3 Tweeting is the top priority so will have it up and running as soon as possible then the nodejs  project will be after that. Have also decided to write blog posts going into a bit more detail about what i am  doing.  They might be a bit random jumping from the nodejs stuff to the space science stuff.  This might mean writing things that are wrong, quite often I do stuff that is wrong and have to go back and re-do them but decided it would be more interesting  than just saying i did stuff and  everything is awesome.

That seems a good place to finish on


Projects X3Prospero

Making a Satellite Tweet

This post is an introduction to a project I'm working on at the moment.  Officially its a work project but I'm finding it so fascinating its taking up quite a lot of my own time.

A while ago my boss asked me to look at making an object in the museum tweet.  Easy I thought we have loads of objects in the museum making one of them tweet will be easy.  Choosing the object to tweet was actually more difficult than I imagined. It needed to be something that could be fully autonomous,  either taking a data feed or generating the text of the tweets itself.  I looked at the some of the well known 'twittering objects' , I  went through a few ideas, talked to several people in the museum and outside but nothing was really clicking.

It wasn't until One sunday afternoon I was sat outside Stepney City Farm drinking coffee and trying to think of ideas.  My eyes looked up to the sky and thats when I came up with the idea of a tweeting satellite.  I knew we had Satellites on display in the Space gallery so  A quick search on the Science museum web site turned up Prospero  The first and only Satellite that Britain launched on a British Rocket.  The actual X3 Prospero is still in orbit, and we have the flight spare on display in gallery.

The project is progressing well.  I have the code written that can send a tweet, as of tonight i am able to obtain the position of X3 Prospero.  The next step will be to put the two together and create a tweet that will be both meaningful and interesting to people.

I'm planning a few blog posts on what I am doing.  These will cover:

The Historical story of the British space programme.

How to write the code to make a satellite tweet  and why  knowing how will help to keep you safe on the web, as with most of my technology posts this will finish with me banging my fist on the desk and calling for everyone to buy a raspberry pi or Arduino and take an interest in the understanding of the internet and web .

Finally the Science of  how satellites orbit  and how to find the position of just about any satellite orbiting the earth right now.


You can follow Prospero on Twitter @X3Prospero Its not saying much right now but you may find some of the test tweets interesting.

But thats it for now.  Here is a picture of the Flight Spare of X3 Prospero  on display in the Space Gallery of the Science Museum.


Flight Spare X3 Prospero
Flight Spare X3 Prospero
By User Geni Wikimedia Commons GFDL CC-BY_SA