NASA MARS Odyssey Orbiter Puts Itself into Standby Safe Mode

NASA's Mars Odyssey orbiter put itself into a precautionary standby status early Friday, June 8, Universal Time (Thursday evening, Pacific Time), when the spacecraft detected unexpected characteristics in movement of one of its reaction wheels.

The spacecraft uses three of these wheels as the primary method for adjusting and maintaining its orientation. It carries a spare reaction wheel.

Odyssey's flight team is in communication with the spacecraft while planning actions in response to Odyssey entering the standby status, which is called safe mode.

"The spacecraft is safe, and information we've received from it indicates the problem is limited to a single reaction wheel," said Odyssey Mission Manager Chris Potts of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

"The path forward is evaluating the health of the reaction wheel and our options for proceeding."

Because the trigger for the incident was limited to a reaction wheel, the spacecraft did not need to completely reboot its computer, as it had in some earlier safing incidents during its record-setting decade of service at Mars. The flight team will be developing a recovery timeline in coming days.

NASA launched the Mars Odyssey spacecraft on April 7, 2001. Odyssey arrived at Mars Oct. 24, 2001.

After arrival, the spacecraft spent several months using a technique called aerobraking, which involved dipping into the Martian atmosphere to adjust its orbit. In February 2002, science operations began. Odyssey has worked at Mars longer than any other mission in history.

Besides conducting its own scientific observations, it serves as a communication relay for robots on the surface of Mars.

NASA plans to use Odyssey and the newer Mars Reconnaissance Orbiter as communication relays for the Mars Science Laboratory mission during the landing and Mars-surface operations of that mission's Curiosity rover.

Inside the iPhone 4's vibrational gyroscope

Apple first announced the iPhone 4’s gyroscope at WWDC 2010, but it was largely overshadowed by other big players inside the phone — the A4 processor, Retina display, and external antennas.

A lot of technology gets stuffed into vibrational gyroscopes (the type found in the iPhone 4), yet a casual observer may barely notice the chip itself, let alone the phenomenal contents within it. iFixit and Chipworks have partnered to show you exactly what’s inside these little gems.

Vibrational gyroscopes have a ton of practical uses, including automotive yaw sensors, game controllers, and image stabilization in cameras.

Now, iPhone 4 applications and games can also benefit from their superb accuracy.

The teardown covers not only the iPhone 4’s gyroscope, but vibrational gyroscopes in general.

We have tried our best to explain how vibrational gyroscopes function and have documented their internals at a microscopic level.

Some findings:

•The iPhone 4 utilizes a microscopic, electronic version of a vibrational gyroscope, called a MEMS gyroscope.
•A microelectromechanical system (MEMS) is an embedded system that integrates electronic and mechanical components at a very small scale.
•A basic MEMS device consists of an ASIC and a micro-machined silicon sensor.
•The AGD1 2022 FP6AQ chip found in the iPhone 4 is a MEMS gyroscope rumored to be designed by STMicroelectronics.
•Chipworks has confirmed that the MEMS gyroscope found inside the iPhone 4 is nearly identical to an off-the-shelf STMicroelectronics L3G4200D gyroscope.
•The picture (above) is that of the GK10A MEMS die, found in the L3G4200D.
•The GK10A is comprised of a plate, called the “proof mass,” that vibrates (oscillates) when a drive signal is applied to set of drive capacitor plates.
•When a user rotates the phone, the proof mass gets displaced in the X, Y, and Z directions by Coriolis forces. An ASIC processor senses the proof mass’ displacement through capacitor plates located underneath the proof mass, as well as finger capacitors at the edges of the package.