The Spacecraft Research Blog

The Sprite is being featured in a series of RadioShack advertisements both in magazines and online.  The first one is out now in the October issue of Wired magazine (page 58).  See it on their website here!

The National Geographic Channel filmed some footage of Laura’s and Joe’s research for an episode of “The Known Universe.” It will debut on Thursday June 9, 2011, at 9:00 pm Pacific.

Satellites come in all sizes–from the tiny ChipSats Zac is working on which are now on the ISS (see previous posts), to the massive communications satellites that bring you your favorite ball game from across the world. One particularly interesting size (at least to me) is the CubeSat size. These satellites are the size of one, two or three blocks (called U’s), each block being a 10cm x 10cm x 10cm cube. A satellite composed of three of these U’s in a row (a 3U CubeSat) is allowed to have a mass of at most 4 kg. At this scale, the satellites are just big enough to incorporate a relevant payload.

This particular shape and mass was standardized as a way to make launches cheaper and easier to attain for university-led projects. Since the standard was introduced in 1999, dozens of CubeSats have been launched into orbit. Most of these have been launched as secondary payloads, taking up some of the extra space on a larger satellite’s rocket. The spacecraft’s standard size also enables the use of readily-available off-the-shelf components, allowing developers to focus on the experimental parts instead of re-inventing routine parts.

So far, CubeSats have been confined to low Earth orbit because no propulsion system available at this scale can give the satellite the energy needed to go beyond. This may soon change, and with that change will come new missions and applications for CubeSats. What follows is a list of what I consider to be the 5 most interesting CubeSat-based missions. While the list is by no means exhaustive, it gives a good idea of the possibilities open to private researchers with relatively little cost. Feel free to post comments with your own ideas for what you’d do with a tiny spacecraft!

1. Earth Observation

The standard mission for a CubeSat in Low Earth Orbit is to communicate with ground stations and in some cases send back a few photos. As smaller and more powerful cameras become available, the resolution and detail of images taken from CubeSats will only improve. Also, with smaller components that allow the satellite to change its orientation (reaction wheels, control moment gyros, magnetic torque coils, etc.) the images will be targeted at specific locations, making them more relevant for Earth observation and studies of everything from land use to atmospheric data. Other types of sensors can be placed in CubeSats to aid in Earth remote sensing–one example of this (a CubeSat that uses magnetometers to observe earthquakes) has already flown. The general idea is that by taking advantage of the cheap, quick access to space provided by CubeSats we can learn more about the Earth.

2. Multi-body reconfiguration experiments

Magnetic flux pinning experiments using CubeSats. (Image courtesy of Joe Shoer)

One of the greatest appeals of CubeSats is that they’re (relatively) cheap to launch and fast to develop, especially when compared to larger, custom-built spacecraft. So, if you want to do experiments that require long exposure to zero-gravity environments, this might be the way to go. One active area of research that can benefit from this is the development of autonomous docking and maneuvering algorithms for large groups of satellites. Having a set of three or more 1U CubeSats that can move around each other would be a great platform for validation of these experiments. Once demonstrated in small-scale on the CubeSats, the same technology can be used in larger systems with more confidence. An example of this is the docking and reconfiguration work being done using magnetic flux pinning right here at SSDS. You can see more about this here.

3. Astronomy

If you’re outfitting your CubeSat with all sorts of cameras to look at the Earth, why not point it the other way? While there are countless things you could study with a cheap telescope in orbit, one interesting proposal for astronomy that can be done with CubeSats is the ExoplanetSat, detailed in this paper.

Essentially, the plan proposed involves a cloud of CubeSats, each with a telescope, tracking bright stars in order to detect Earth-like planets orbiting other stars.

4. Orbit the Moon

This is my personal favorite. Getting a CubeSat to go to the Moon might seem pretty far off. We all remember images of the Apollo missions, with giant rockets blasting off into space, using tons of fuel in seconds. How could something the size of a milk jug get to the Moon too?

Concept for a propulsion-enabled CubeSat

By hitchhiking part of the way on the same rocket as a larger satellite, CubeSats are able to gain much of the energy necessary to escape Earth orbit. A much smaller propulsion system, maybe even one that fits inside the small volume of a CubeSat, can then take the satellite the rest of the way to the moon. Depending on what orbit the CubeSat is released and what trajectory is chosen, the size of the propulsion system necessary can be reduced. While the Apollo spacecraft allowed astronauts to get to the moon in a matter of days, if time is not an issue, there are ways to trade time for propellant savings. This way, a CubeSat can get to the Moon in a few months, but much more efficiently than the Apollo missions. Getting anywhere near the Moon is beyond the capabilities of any propulsion system that has flown on a CubeSat to date, but here at SSDS we are hoping to soon change that.

5. Deliver ChipSats to cool places

ChipSats are far smaller than CubeSats, but their high surface area to mass ratio allows them to do things larger satellites can’t dream of. At the ChipSat scale, effects such as air drag, solar pressure and electromagnetic forces become much more important and affect the chip’s orbit significantly. Using a CubeSat as a way to deploy ChipSats can change where and how ChipSats can be deployed. From low Earth orbit, the CubeSat can time the release of the chips, which will then flutter downwards and cover a target area. If the CubeSat has propulsion, it can eject the chips in higher orbits where solar pressure forces are stronger than gravity. The chips can then use solar pressure to sail away from the Earth and explore the far reaches of the Solar System.

No-one else is calling it the Sprite Spacewalk, but I suppose we all have different priorities.

A few days ago astronaut Drew Feustel installed the ISS experiment, called MISSE-8, where the Sprite prototypes reside. The MISSE-8 hardware apparently deploys open in a way that may have exposed the prototypes to the sun and the earth in a convenient way to receive the data. So, was it possible for us to get that data?

I have not yet located NASA TV footage of the exact moment at which the MISSE-8 hardware opened up to expose Sprite to the sun for the first time. However, according to this video, EVA 1 for STS-134 was on mission day. The date was therefore roughly 5/20.

The MISSE activities are shown starting at 7:00 in the video. At 8:02 you see how they install MISSE-8, replacing MISSE-7a. It’s only when the MISSE-8 hardware opens that there’s some chance of a non-zenith exposure of the Sprite prototypes. After that, they face zenith (or antinadir) unless ISS undergoes some atypical attitude maneuver.

We have an antenna on Mount Pleasant, in Ithaca NY, that ought to be able to receive RF emissions from the prototypes if ISS is in view and if the antenna pattern of the Sprites and the ground line up. ISS will be visible from Ithaca at certain rare times as spelled out here:

Specifically,
SATELLITE LOCAL DURATION MAX ELEV APPROACH DEPARTURE
DATE/TIME (MIN) (DEG) (DEG-DIR) (DEG-DIR)

ISS Thu May 26/04:51 AM 3 15 10 above S 10 above E
ISS Sat May 28/04:03 AM 3 15 13 above SSE 10 above E

Try your own location. If you have HAM equipment capable of 902 MHz, please get in touch with us about exactly what to look for. When I figure out the exact time of the deployment, I’ll be able to estimate where ISS was at that instant. Then we may try to find out if anyone in that area was looking at ISS with a 920 MHz capable antenna at that time.

So, the installation events were not visible from Ithaca. Maybe some of us will be awake at 4:00 am in the next few days for our first shot at getting data, or maybe we’ll just wait until the pass geometry and our biological clocks are better aligned.

Hello blogosphere!  This post marks both the launch of our blog here at the Cornell Space Systems Design Studio, and the launch of three of our prototype Sprite “ChipSats” onboard Space Shuttle Endeavour.   Here I am talking about it on the local news:

I’ll post updates here as we try to detect signals from the Sprites when they fly over Ithaca – stay tuned! To learn more about our goal of building a complete spacecraft-on-a-chip, as well as some other really interesting projects, check out our group’s website.