Soaring 500 miles above Earth, a tiny British satellite built around a commercial smartphone was calling back to Earth on Tuesday, one day after launching from India.

Animation of the smartphone satellite. Credit: SSTL
 
But the satellite's biggest test is still to come, when engineers will switch its operating system to the Google Nexus One smartphone at the heart of the 9.4-pound miniature spacecraft.

For now, the STRaND 1 satellite is running on a standard computer system. It will next be transitioned to a Linux-based high-speed processor and once engineers are comfortable with the satellite's performance, they will turn over control of the spacecraft to the smartphone computer.

"We won't switch to the phone until all the satellite's own systems are all checked and working nominally," said Joelle Sykes, a spokesperson with Surrey Satellite Technology Ltd., the UK-based manufacturer of the STRaND 1 satellite. "Then the phone's health gets checked out before we can switch any [operations] to it."

Officials with SSTL and the Surrey Space Center expect the commissioning phase to last about two weeks.

"STRaND-1 from SSC and SSTL is an example of the real synergy of academic research linked to commercial development and exploitation that is the hallmark of Surrey," said Martin Sweeting, director of the Surrey Space Center and executive chairman of SSTL, in a statement. "This mission is a fantastic achievement and a great tribute to the hard work of the engineers involved. The UK's first nanosatellite SNAP 1, also built by SSC and SSTL and launched in 2000, was the world's most advanced nanosatellite at the time - STRaND-1 continues that story with the latest technologies available to us in 2013."

Based on the popular CubeSat design, the satellite is about the size of a household toaster oven, but engineers packed the tiny spacecraft with pulsed plasma thrusters and an experimental water-alcohol propulsion system - both first-time payloads on a nanosatellite - to remove STRaND 1 from orbit at the end of its mission.

Surrey engineers started working on their project in their free time in 2011, and technicians assembled the satellite in just three months beginning in late 2012.

Photo of the STRaND 1 satellite assembled before launch. Credit: SSTL

Although officials have not divulged the exact cost of the project, Sykes said the cost was comparable to that of a family-sized car.

Smartphones have flown in space before inside the International Space Station, and the computer from a PDA launched inside two Japanese CubeSats in 2006 and 2008.

But STRaND 1 will go a step further.

The Nexus One's Android operating system will take over most of the satellite's control functions, testing the phone's ruggedness in one of the most inhospitable environments imaginable.

Engineers beefed up the phone with radiation shielding, and designers took precautions to keep the phone's battery from getting too cold in space.

"A smartphone on a satellite like this has never been launched before but our tests have been pretty thorough, subjecting the phone to oven and freezer temperatures, to a vacuum and blasting it with radiation," said Chris Bridges, Surrey's lead engineer on the project. "It has a good chance of working as it should, but you can never make true design evolutions or foster innovation without taking a few risks. STRaND is cool because it allows us to do just that."

The phone is mounted on a panel inside the satellite, with its camera aligned with a hole to take pictures of Earth.

STRaND 1 also features what Surrey engineers claim is the first 3D printed component to fly in space.

Applications installed on the smartphone will help control the satellite, collect scientific data and try to boost interest in space exploration.

The apps were selected in a Facebook competition last year:

• The Scream in Space app was developed by Cambridge University Space Flight and will make full use of the smartphone's speakers. Testing the theory "in space no one can hear you scream," made popular in the 1979 film "Alien," the app will play videos of the best screams while in orbit, and the screams will be recorded using the smartphone's own microphone.
  
  
• iTesa will record the magnitude of the magnetic field around the phone in orbit. Used as a precursor to further scientific studies, such as detecting Alfven waves - magnetic oscillations in our upper atmosphere - the iTEsa app could provide proof of principle.
  
  
• The STRAND Data app will show satellite telemetry on the smartphone's display, which can be imaged by an additional camera on-board. This will enable new graphical telemetry to interpret trends.
  
  
• The 360 app will take images using the smartphone's camera and use the technology onboard the spacecraft to establish STRaND-1's position. The public will be able to request their own unique satellite image of Earth through the website, where images can be seen on a map showing where they have been acquired.

Amateur radio operators can listen to STRaND 1's signal as it goes overhead. Learn how to listen here.

NASA's answer to STRaND 1, named PhoneSat, will launch this spring. Three PhoneSats, all using Android operating systems, are slated to fly together on the first mission of the Orbital Sciences Corp. Antares rocket.

Surrey engineers are already working on a follow-up mission named STRaND 2. It will test the ability of two CubeSats to dock together in orbit using technology from Microsoft Xbox Kinect game controllers providing three-dimensional spatial awareness.