Satellites controlled by a smart phone? Tiny CubeSats reach space.
When Orbital Sciences Corporation launched a Minotaur rocket from the Virginia coast last month, along with its primary payload it carried 28 tiny satellites that over the past decade have come to represent a democratization of space, of sorts.
They are known as CubeSats. About the size of a loaf of bread or smaller, the CubeSat has morphed from a educational tool for university undergraduate and graduate students to a low-cost research tool for developing satellite technology and for Earth and space sciences.
CubeSat technology has become so accessible that one launched Tuesday uses an Android smart phone as its control system while another was built by (very smart) high school students at the Thomas Jefferson High School for Science at Technology in Alexandria, Va.
The TJ3Sat satellite, which converts text messages into voice messages that can be radioed back to Earth, is the first built by high-school students anywhere to be lofted into space. Another CubeSat, built by students at Merritt Island High School, is in the pipeline for next year. Their satellite, dubbed StangSat, is designed to help test new communications systems for future CubeSats aimed at simplifying the radios such satellites carry to send data back to Earth.
At the other end of the sophistication spectrum, researchers and students at the Massachusetts Institute of Technology are developing mini-space telescopes designed to hunt for planets orbiting nearby stars.
Even hobbyists have gotten into the act. Enthusiasts of amateur radio (called ham radio), who have been using specially designed satellites for communications since 1961, were looking forward to the launch Nov. 21 of FUNcube-1, a CubeSat built by British and Dutch amateur-radio operators. The satellite is the centerpiece of a science education effort for secondary schools, as well as a way for ham-radio operators worldwide to communicate.
Twelve of the satellites aboard the Minotaur operate on ham-radio frequencies, which means amateur radio operators can help monitor the tiny craft.
These satellites include a pair designed to see if a shared tether can be used as propulsion for small spacecraft, as well as PhoneSat 2.4, a NASA CubeSat that is exploring the use Android smart phones to control satellites. Smaller, lighter, more-powerful computing power reduces the weight of a basic spacecraft, allowing scientists to pack it with more science instruments than might otherwise be possible.
The agency launched its first PhoneSats in April, appropriately named Alexander, Graham, and Bell. They were short-lived by design, just to test the basic idea. But PhoneSat 2.4 is designed to orbit for about two years, and includes two-way communications capabilities as well as the ability to control the satellite’s orientation. Among other things, mission engineers want to see how the reliable the electronics are after two-years’ exposure to radiation in space.
Engineers are also looking for ways to reduce the weight of the small launchers that attach to the main spacecraft and eject the CubeSats at the right point in the rocket’s ascent. The CubeSats currently weigh 2.9 pounds per cube, each roughly 4 inches on a side, and any weight that can be removed from the launch mechanism translates into additional ounces available for instruments.
As if to underscore the increasing access to space these diminutive satellites can provide, it took 10 years to launch roughly 75 CubeSats, with varying degrees of success. In 2006, 14 CubeSats were lost when the Russian Dnepr rocket carrying them failed to reach orbit. Tuesday’s Minotaur launch lofted 28.
Reports from ham-radio operators suggest one by one the satellites are phoning home.
Credit: Pete Spotts