I have chosen the visualization - "The World Above us". This is a visualzation of all the active satellites orbiting the earth. This was very interesting as it shows us a summary of what the satellites above us really do, the age of the satellites and who really owns them. Scroll down for more information and my critique on the visualization or click below for the app.
The first section of the page contains introduction to the application. The data source is mentioned along with the date limit to which the data is visualized. Then the size and color filters used for representing the satellites are shown.
The second section of the app is where the visualization begins. It starts by showing a 100kms distance from the earth which is where the space actually begins.There is a data snippet giving details on where the app really begins. The control to set the satellites into motion in the orbits is also mentioned.
The next is where the lower earth orbit is represented. This is where a majority of the satellites seem to be present. The iridium constellation and the oldest satellite - Amsat Oscar 7 are mentioned in data snippets.
There is an option midway through the app to change the color of the satellites based on the age of the satellites and also color based on the country which launched the satellite.
Then there is also an option to change the color of the satellites based on the primary user. Then comes the representation of the medium earth orbit. The geostationary orbit is the next level where the satellites density is high.
The last section of the visualization is from the higher earth orbit to the moon. The number of satellites is very less in this region when compared to the other orbits.
Clicking and hovering on a particular satellite brings up the information and the elliptical path of the satellite.
The footer contains a note on excluded satellites and the control to set the satellites in motion with relative speeds.
The data for the application as mentioned by the developers is taken from a database compiled by the Union of Concerned Scientists(UCS). Click here for the data source. The following points summarize what the data is all about.
The database used for the application is the data collected untill August 21st, 2014. But the data present now is for all satellites active untill September 1st, 2015.
The data for each satellite is covered over 35 data points. These data points include the technical information(mass,power,launch date etc), the information on who built, who owns the satellite and also the primary users of the satellite.
The data compilers have also provided a guide on how to interpret the data from the database.
There is also a very useful pdf on common misconceptions for gaining clarity on the domain.
Satellites in numbers
There are totally 1305 active satellites operating around the earth.
USA owns the highest number of satellites - 549 followed by China(142) and Russia(131).
Of the 549 satellites owned by the USA, 250 of them are of commercial use while 152 are for military usage.
The average cost for launching satellite is $4653 per kg of a satellite.
The heaviest unmanned satelites are American Keyhole spy sats weighing 10,000 kg as much as a school bus and the smallest is the cubseats weighing at 1kg.
The ISS has grown from 19,200kg to 420,000 kg today.
The largest private satellite constellation belongs to Iridium Communications which has 71 satellites in orbit.
The oldest satellite is Amsat Oscar 7, launched in 1974.
In 2013, the UN received 4500 applications fro 72 countries to launch satellites.
America has a space budget of $39billion which is the largest in the world.
The most distant orbiter from earth is a NASA satellite studying solar wind at an orbit peak of 470,310 km.
The following are my observations in the app which contriute to it being a good visualization.
Due credits is given for the data source. The date for the data is also mentioned which gives the user an understanding of the data.
The size representation of the satellite is reasonable and easy to identify according to the launch weight in kgs. Likewise, the color is also given good importance and different filter categories are provided to change the color. The colors dont have precednece over each other and are distinct enough to identify them. The weight unit is also mentioned.
Good information across the visualization to help the user identify the distance from earth.
Interesting data snippets across the visualization to keep the user interested and stick to the specific layer in the visualization.
As the visualization is made scrollable, everytime the user wants to change the color filters, one needs to scroll to the top to change it. So to kind of solve the issue, the app has filters positioned in between the visualizations which is a reasonable solution to the problem.
The color index for the selected filter is shown(not all but the major proportion) at the description as well.
Very good feature to show the elliptical path and the relative speeds of the satellites.
The following are my observations in the app on which there could be improvement to make the app perfect.
The whole visualization is not viewable on a single screenshot. It needs to be scrolled down which is a drawback.
The line drawn to represent the distance from the earth and the font color could have been made more distinct to be able to identify at the first glance.
There is no source to identify the filter we choose when we are in the middle of the page.
Selecting a particular satellite is a bit tough at the geostationary level where the density is very high.
The spacing between different heights from the earth is not even which could be a minor issue if the users make rough estimates quickly.
Following were some questions I asked to evaluate the effectiveness of the application as a tool for understanding our satellites.
How many satellites does a given country have in orbit, and what are they used for?
As such we cannot tell the total number of satellites for each country but it is definitely possible to see an estimate based on color of the satellites. The primary usage can also be seen similarily and also by hovering over the satellite.
How many satellites are used for military purposes versus commercial purposes?
Again as such we cannot tell the total number of satellites precisely but it is definitely possible to see an estimate based on color of the satellites.
Which countries have earth-observing satellites?
The app provides us a way to either select the country or primary usage and view the other accordingly. But at one go we cant see both the data facts together.
When was the oldest working satellite launched?
Thanks to the data snippets, we can actually see the oldest launched satellite at one click and that is really useful.
At what altitudes do most satellites orbit?
The visualization can be effectively used to gain a reasonable estimate of which height has the most number of satellites. Since the question is not very precise, it is possible to get a definite answer for the question.
What activities are most satellites involved with?
The color by primary use filter provides us an option to answer this question. The color can change depending on the usage and we can get an overview of which usage is high compared to the others.
On the whole, the visualization is very interesting as it provides us with an effective tool to visualize the various satellites in one go. It answers major questions one can possibly come up with the statistics of satellites. It also provides us a chance to know about interesting satellite orbits and satellites as such. There is some room for improvement when we look at it from a technical point of view of a satellite as to how technically can the visualization be helpful for researchers. With due credit to the developers, the app is a very interesting and an efficient tool.