KickSat will fly again! I was just notified that KickSat-2 has been selected for a launch by NASA's CubeSat Launch Initiative. You can read more about it on NASA's website. In addition to KickSat-2, thirteen other CubeSat teams were selected from all over the U.S.
We don't yet know when our launch will be, but I will be sure to keep you updated. Thanks again to all of you for your support over the past three years.
My name is Marc Choueiri and I am one of KickSat’s newest members. This is my first blog post and although I can’t entice you with the same technical details as Zac, I can tell you a little about myself, what I do for the project and why I love working for KickSat.
A born and raised New Yorker, I followed in my father’s footsteps coming to Cornell to pursue mechanical engineering. I joined KickSat this past summer and have stayed on the team for the academic year. I am part of the project’s mechanical team and am responsible for all mechanical components of KickSat.
Recently, my main focus has been working on KickSat’s deployment system for Sprites. For those of you who are unfamiliar with ‘KickSat’ terminology, Sprites are the femtosatellites we expect to deploy in low Earth orbit. They are 3.5cm x 3.5 cm x 2mm circuit boards with sensors, solar panels, a radio and an antenna.
I have been improving the design of the deployment system and building two new iterations for our planned future launches. The system consists of several aluminum deployer pieces tensioned with springs and held in place by a locking mechanism. When the satellite is at the proper altitude, a burn wire is activated that releases the locking mechanism. The Sprites, whose antennas double as deployment springs, are released into orbit at an altitude of around 300 km. See the pictures and video below to get an idea of how the deployment system works:
I enjoy studying mechanical engineering but most of the work we do is theoretical and not hands-on. That is one reason I am grateful to be part of this project. I work with the worlds' smallest satellites and something I help build with my own hands will be soon be in space. KickSat has given my colleagues and me a unique opportunity that not many other engineers at Cornell get to experience. Most importantly, the work we do also has direct application to life outside the classroom.
A question I get a lot is what is KickSat's ultimate goal? When can it be determined the project was successful? Although I can't speak for Zac, I say one of the two milestones that will signal to me the full accomplishment of the KickSat mission is to have Sprites deployed (by anyone) into another planet’s atmosphere. The concept is very inexpensive and would be ideal for studying other planets. It would be unfortunate to see KickSat have the same fate as most research projects and end up on the shelf. The other milestone would be to see crowd-funded space exploration projects being done on a mass scale. KickSat is a leader in inexpensive space exploration so hopefully it will pave the way for many other future projects. With those two things accomplished, I will be fully content with how far KickSat has come.
We know so little about space so hopefully the technological innovations from the KickSat project will help us change that. It's not on the same scale as the Curiosity Rover or MAVEN but certainly a step in the right direction.
Sorry for the very long absence. It's been a busy fall here at Cornell. The KickSat team has grown to include five new undergrad students and one new part-time engineer this semester. In the coming weeks we'll have guest blog posts from each new team member so you can learn what everyone is up to.
One of our group's highlights this fall was hosting NASA administrator Charles Bolden in our lab. Here he is holding a Sprite!
Administrator Bolden's visit was truly inspiring and it was very cool being able to personally show him KickSat.
On the technical side, we've made numerous improvements to the KickSat mothership design, including new power regulators, solar panels, and radios. We're also working on adding a GPS receiver so that the spacecraft will know when it's over our ground station and can turn it's receive radio on and off appropriately to save power. All of this work is being incorporated into KickSat-2, which we hope to have ready for launch in early spring. As usual, you can see our designs and follow along with our progress on GitHub.
That's it for now. We'll be posting a lot more in the next few weeks. As always, thanks for your support.
Remember the prototype Sprites I showed off during my original Kickstarter video?
Those were from the first batch of Sprites we made back in 2010. As some of you may know, we were lucky enough to be able to send three of those early prototypes to the ISS on STS-134 (the second-to-last Space Shuttle mission). The Sprites were installed on the outside of the space station as part of the MISSE-8 experiment, where they stayed for three years. Here are a couple of pictures from the spacewalk when MISSE-8 was installed (notice the three Sprites in the second photo).
In a very cool turn of events, MISSE-8 was returned to Earth on May 18 inside the same Dragon capsule that KickSat rode into space with as part of the CRS-3 mission. A few days ago our Sprites finally finished their long journey, making it all the way back to the lab at Cornell where they were made. As you can see, they've clearly been through a lot.
We were very curious to see how well the Sprites' off-the-shelf electronics held up to three years of space radiation. After a quick trip to the hardware store to track down an incandescent lamp (thanks to Ithaca's rainy weather, there wasn't enough real sunlight to power the Sprite's solar cells), we were to detect strong radio transmissions from two of the three Sprites. We still have a lot more testing to do, but this is a very promising first indication that the components we're using on the Sprites can survive for long periods of time in the harsh space environment. I'll keep you all posted as we learn more.
In addition to looking into new radios for KickSat-2, I've also spent some time over the last couple of weeks redesigning KickSat's antenna. KickSat-1, like many CubeSats, used a simple quarter-wave monopole antenna made from a piece of Stanley tape measure (yes, cut from an actual tape measure). The beauty of this design is that the tape measure can be folded flush against the CubeSat structure for launch and will snap out straight once the CubeSat is deployed.
While the tape measure monopole is simple and elegant from a mechanical perspective, it doesn't provide very good RF performance. One reason for this is that a monopole antenna needs to be mounted perpendicular to a large ground plane, and a CubeSat structure isn't quite big enough to be effective in that role. Another reason is that there are impedance matching issues when connecting a monopole to a radio. Basically, without careful engineering, a lot of RF energy is reflected back into the transmitter by the antenna. The reflections result in a loss of efficiency and, in extreme cases, can actually damage the radio.
Because radio waves interact in complicated ways with the metal structure of the satellite, we have to use a computer to simulate different antenna designs. Here is a simulated gain pattern from KickSat's original monopole antenna showing where the radiated signal is strongest and weakest:
Even more important than the gain pattern is a number called the standing wave ratio, or SWR. The SWR tells us how much reflection is going on between the antenna and the transmitter, with a value of one corresponding to the ideal no-reflection case. The higher the SWR, the more reflection, and the lower the power tranfer efficiency between radio and antenna. The monopole antenna simulation gave an SWR of nearly 4000 - not so good.
Here is the new design I came up with this week. It consists of two pieces of tape measure forming a slightly bent dipole antenna, like the "bunny ears" many of us used to have on our TVs.
The simulated SWR of this new antenna is 1.2 - close to a perfect match! That should help us squeeze much more efficiency out of our radio, ultimately making KickSat-2 easier to hear and easier to command than KickSat-1 was.
That's it for this week. I'll be back with more news next Friday. Thanks again for your support!