SpaceLab for iOS is a commercially developed app by Odyssey Space Research to work with Apple’s iOS on iPhone® 4 in order to perform experiments onboard the U.S. National Laboratory on the International Space Station (ISS). The SpaceLab for iOS app was transported to the ISS on two, space certified iPhone 4’s on the historic final mission of the Space Shuttle program, STS-135, on the orbiter Atlantis. The purpose of SpaceLab for iOS is to demonstrate that an inexpensive consumer electronics device can perform tasks previously reserved for expensive single purpose devices. Modern smart phones contain hardware once only found in expensive avionics. Where an avionics box may have had a limited production run of 100’s or 1000’s of devices, a smart phone may have a similar engineer investment but a longer production run of millions, which significantly lowers the cost for users of the device. The goal of this project is to significantly lower the cost of space flight and lower the barrier to access in space.
The iPhone® 4 was chosen because it was the first widely accessible hand held consumer electronics device with a high resolution display, tactile interface, high density storage, 3-axis accelerometer, and 3-axis gyro. A series of 4 experiments were selected that, when combined, could prove that such a device could be used to locate a space vehicle relative to Earth. Space flight software is often created with expensive specialized software, so SpaceLab for iOS was purposefully created using open source or free software when available. All the software is written with XCode, which is free from the Apple website. Most graphics were created with Gimp, which is a popular open source graphics tool. Even some of the mathematical algorithms were designed and tested using Octave, an open source math utility, before being converted to code. During development, bug tracking was performed by Trac and version control by Git, both open source utilities. The idea is that this is an avionics platform that many college students already have, and they can write software for it using open source tools.
The two smartphones are currently onboard the ISS. We are finalizing approval of the procedure and crew training, and plan to have the smartphones unpacked and being used shortly.
Four experiments are planned. The experiments contain step-by-step procedures to allow a crew member to conduct the experiments without the need for supplementary paper procedures.
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. When returned to the ground, this data will be used to calibrate the camera lens, which may have shifted during launch.
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. The calibrated optics will be used to calibrate the motion sensors by providing a second means to determine movement.
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.
iPhone 4 was certified for spaceflight and was transported to the ISS on the Space Shuttle via NanoRacks, LLC of Houston, Texas. NanoRacks provides low-cost hardware and integration services for the U.S. National Laboratory onboard the ISS. Both iPhone 4’s will remain on the ISS for several months where the experiments will be conducted by the crew and data acquired and stored on the devices.
The app is available for download on the App Store℠ so that ground based users can get a sense of experience and tasks to be performed by crew members on the ISS. Some features are simulated to account for the presence of gravity.
When the experiments are completed, both iPhones will be returned to Earth. The first opportunity for return will be on a Russian Soyuz vehicle in the spring of 2012. Flight data from the experiments are expected to be collected, analyzed, and then shared via this app on the App Store.
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Johnson Space Center