In the movie Wall-e, there is a scene where the Earth is surrounded by billions of satellites, decorating the blue orb like garbage thrown on a Christmas tree. It made me wonder what exactly is happening up there right now. After talking with other researchers and attending a symposium on new satellite policy, I found the major technological thrust is Cubesats.
While researching Cubesats I wanted to share what I've been learning in a series of posts. In this post, I hope to educate those interested in Cubesats by answering the following questions:
- What exactly is a Cubesat?
- What are Cubesats doing up there?
- What is the future for Cubesats?
What exactly is a Cubesat?
Cubesats come in U or unit/cube form factors, where each U is roughly a 10 cm X 10 cm X 10 cm and a mass up to 1.3 kg. Radius Space shared the graphic below on their website showing the different form factors of Cubesats. Starting at the left in the figure below, these are 12U, 6U, 3U, 2U and 1U Cubesat form factors. With the largest configuration shown, the rack on the far left, a 12U cubesat, would weigh at most 15.6 kg.
Using Cubesats as standardized payloads, researchers or companies can take advantage of economies of scale and increase their access to space. Additionally, commercial off the shelf hardware is becoming available so developers can build custom payloads easily. With each Cubesat's expected life to be 1-3 years, constellations can be updated more quickly with better hardware at lower costs.
Most Cubesats are put into orbit through a ride share with a launch company. It's estimated that each cube costs about $40,000 to launch. I learned last month that there is a new demand for launch services of this type.
It's also important to note that most Cubesats are not going far into space. Many of the Cubesats are deployed from the International Space Station (ISS), which is around 400 km (250 mi) in altitude. This altitude is referred to as Low Earth Orbit (LEO). This photo below, taken by Astronaut Koichi Wakata, shows two 3U Planet Labs satellites being deployed from the ISS. Most communications satellites that provide well known services use a Geosynchronous Earth Orbit (GEO), which has an altitude of 35,786 km.
Dr. Swartwout, from St. Louis University, has created a data base of all the currently deployed Cubesats to date. From this data, I created this chart to illustrate what form factors of Cubesats have been deployed. There is basically two sizes currently in orbit 1U and 3U.
What are they doing up there?
Using data from Dr. Swartwout, the increased access to space was definitely shown to be successful by the chart below. Since 2013, there has been dramatic increase in the number of launches of Cubesats. Most them, until recently, have been for university research and used in technology demonstration and education purposes. The majority of these university Cubesats, 70%, have been the 1U form factor. However, In the last two years, there has been a significant increase in commercial use (and 3U Cubesats) from one company called Planet Labs.
With 135 satellites, Planet Labs has successfully deployed the most Cubesats to date. Their mission: to map every 3 meters of the earth into a pixel using their Dove satellite, which is shown below. I encourage you to visit the website to learn more about what they've done.
What is the future for Cubesats?
It's important to mention there is some confusion when it comes to satellite categories when discussing weight and Cubesats. Spaceworks provided the following guidance for satellite sizes, and I found this consistent with other sources of information while doing my research. Again for perspective, GEO satellites can be on the order of many tonnes (thousand kilograms).
Northern Sky Research (NSR) and Spaceworks have both made predictions for Cubesats. Unfortunately, Cubesats can span a wide range of weight, which makes it a little difficult in looking at these predictions from NSR from early 2015. Right now, I don't have a feeling for anything above 10 kg. However, you'll see roughly 30% increase launches in 2016 from 2015. I would have to say NSR did a fairly decent job in terms of short term predictions, since they are consistent with Dr. Swartwout's data.
Spaceworks provided these more optimistic predictions in 2014.
Based on Spaceworks and NSR data, launches of Cubesats could continue at their current rate, with most of their applications being earth observing. I'm showing the Spaceworks figure below, which is consistent with the NSR data. I'm surprised that not more of these Cubesats will be used for communications.
In a nutshell, Cubesats are about a hundred times closer to earth, a thousand times lighter, and cheaper than GEO satellites. If the given predictions are true, we should see about 250 new Cubesats each year. Most of these satellites will be performing earth observing missions. One application could be a real-time Google Earth.
Or course, there are still many questions to Cubesats. How much 'space junk' is up there an how? Do we need some type of space traffic control to steer around it? What about space garbage collection? How do the Cubesats get information back to the ground? How are they steered around? How do you get a Cubesat launched? I planning on answering these questions in a latter posts.
Let me know what you think in the comments.