Space shuttle, Atlantis, was launched from Kennedy Space Center this morning at 11:29am. STS-135 is the last mission of over 30 years of space exploration. The two iPhone 4s taken into space are pre-loaded with the app SpaceLab for iOS, which will allow scientists to conduct several experiments, including the following -

Limb Tracker - This navigation experiment will involve taking photographs of the Earth and matching an arc to the horizon through manipulation of an overlay. This performs the function roughly equivalent to a “manual” horizon sensor. It will yield an estimate of altitude (height above the surface) and “off axis” angle, a measurement of the angle of the image with respect to the Earth's center.

Sensor Cal - This sensor calibration experiment uses a series of photos of a reference image, combined with propagated information using three-axis gyro and accelerometer measurements to calibrate the gyros and the accelerometers (i.e. bias and scale coefficients). This will improve the knowledge and accuracy of subsequent measurements.

State Acq State Acquisition - This navigation experiment uses a series of photos of a reference image and of the Earth, combined with information from the three-axis gyro and accelerometer, to estimate the position of the spacecraft (latitude and longitude). The position estimation is generated by manipulating and matching a wireframe overlay of the Earth's coastlines to the acquired Earth image(s). Performing multiple sequences, separated by a known amount of time, can permit estimation of the spacecraft's orbit parameters.

LFI Lifecycle Flight Instrumentation - This experiment will characterize the effects of radiation on the device by monitoring certain areas of memory for Single Bit Upsets - an unintended change in value of a memory location caused by exposure to radiation.

The iPhone's three-axis gyroscopes and accelerometer should perform well in zero gravity and let scientists conduct experiments in a more cost efficient way. The mission will last 12 days but the iPhones will remain in space. The Russian Soyuz vehicle will return the iPhone 4's to Earth possibly as soon as this Fall. Flight data will be collected and analyzed once they return to Earth.

You can check out SpaceLab for iOS in the App Store now (iTunes Link). Not all experiments will work without a zero gravity environment but it's still an extremely interesting app to check out.