A key question for future deep-space human missions is under what operational conditions and scenarios is it advantageous for crew to operate a robot “locally” versus controlling it from mission control on Earth? Future human missions to the moon, Mars, and other destinations offer many new opportunities for exploration. But, crew time will always be limited and some work will not be feasible for astronauts to do manually. Robots, however, can complement human explorers, performing work under remote control from a crew vehicle, or even from Earth.
The HET Smartphone project will explore how we can use free flying robots to augment and support crew activities. It uses the MIT SPHERE Satellite, which is a self-contained free flyer with power, propulsion, computing and navigation equipment. For our experiments, the Samsung Nexus S Smartphone is connected to the SPHERES free flyer through a communication cable. A wireless network connection to the ISS provides the data path to the ground. The Nexus S acts as an embedded computing platform and integrated sensor package since it has gyros (position), accelerometers (movement), magnetometers (compass), cameras, and microphones. The size and integration of the components make it an ideal platform for experiments like this.
Is this the first smartphone to communicate from the ISS?
Yes. This Google Android Nexus S will be the first smartphone to communicate from the ISS to the ground.
How do you plan to control the Smartphone? Is it like a radio-controlled toy?
Communications to and from the ISS can often be delayed as much as 6 seconds and there are regular communication outages due to ground station coverage. As such, we plan to use very high-level control for the Smartphone. “Navigate to this location.” “Look over here.” “Follow this path,” are just some examples of the types of command series that we might send to the Smartphone from Earth. The significant delay will prohibit us from flying the Smartphone the way that a person might “joystick” a radio-controlled toy on earth.
Will the SPHERES and Smartphone go outside of the ISS?
No. Currently the equipment is designed to operate within the atmosphere of the ISS. That said, the experiments that use the Smartphone are being used to explore how this technology might be used inside, and outside spacecraft on future missions.
What hardware modifications did you make to the phone?
The make it through flight qualifications, the team made two major modifications to the phone. First we removed the GSM chip on the phone so that the cell phone transmitter would not interfere with ISS equipment. This modification can be thought of as hardware “airplane mode” and is done for the same reason that you turn off your cell phone on airplanes.
The second modification was the removal of the Lithium batteries. Lithium rechargeable batteries are difficult to certify for flight, so we decided that using safer Alkaline AA batteries would be appropriate. We power the phone with 6 AA batteries that are connected to a DC regulator that makes the voltage compatible with the phone.
What software modifications did you make to the Android operating system?
We needed to load Android programs on the phone via the internal SD card and download movies and telemetry data from the phone’s SD card. The majority laptops on the ISS are Windows XP SP3. Since the Nexus S is a very new phone, we found that XP had some problems identifying the mass storage device functionality of Android.
We modified how the phone emulates a mass storage device by emulating the USB hardware ID of a Nexus One (which did work correctly) and allowed the user to enable the mass storage device mode prior to plugging in the USB cable.
The wireless tethering mode was also modified. In the even that we need to connect a laptop to the phone directly, we modified the wireless tethering feature so that it can act as an AP, but then the phone routes traffic through the connecting laptop. This is backwards from the normal mode of operation, where the connecting laptop routes its traffic through the phone.
Were there other safety modifications that you made to the phones?
There was a concern that the glass screen might break and eject material into the ISS. We discovered that the capacitive touch screen worked with Acrylic and Teflon tape covering the screen surface. So, during flight preparation we applied Teflon tape to the front of the phone and then trimmed the tape to the outside edge of the phone. In the event of a glass breakage event, the Teflon tape would contain the glass and ensure that no material escapes.
Is the software available to download on my Android phone?
For general data collection our first experiments, we used the Cellbots logger by Google. It is available on the Android Market — It is an open source sensor data logger and the version that will be running on the ISS only changes the icons to comply with NASA interface guidelines.