In The News

Genesis Mission

We really need to know what the initial composition of the Solar System was and we'll get that by measuring the oxygen that came from the solar wind   

Dr Ian Franchi, OU

The Genesis spacecraft opened for collection of solar wind.

• This artist's conception of the Genesis spacecraft shows it in full operational mode, opened up to collect and store samples of solar wind particles.

• The cover of the science canister, shown on the right, contains one set of collection materials. It is the same kind of hexagonal silicon wafer array that comprises the stack of four arrays that were rotated out of the interior of the canister when the spacecraft began to orbit L1.

• The bottom three of the stacked arrays are controlled independently, and may be rotated out from the cover of the top of the stack to collect particular types of solar wind.

• Inside the canister is an electrostatic concentrator to increase the collection of light-weight solar wind particles. It is exposed when the array stack is rotated out.

• The two solar panels, shown in blue in this drawing, which extend to the side of the spacecraft bus, provide electrical energy for the functions performed by the rest of the spacecraft.

• The two balls, shown in pink in this drawing, which sit at the sides of the spacecraft contain fuel for the small thruster rockets that maintain the Genesis spacecraft's orientation facing the Sun during its collection phase.

Video of Landing

• genesis.mov

Genesis.mov

193 mph

193 mph

Mishap Investigation

• ‘Investigators report a likely reason Genesis' chutes did not open was a faulty design that had these switches improperly installed on a circuit board.’ -NASA

One of Two Avionics Units Each Unit has Two G-Switches

Mishap Details

• Genesis' gravity-switches were responsible for detecting the spacecraft's braking motion when it began the high-speed reentry into the Earth's atmosphere. The pencil-thick cylinders are small, about three-quarters of an inch, and from the outside quite easy to mix up which end goes where, investigators said.

• The switches were expected to sense the braking, then initiate the timing sequence that would deploy a drogue parachute and parafoil and their appropriate times. The entire sequence takes about 5.5 seconds. Only two of the four switches aboard the capsule had to work properly to secure the probe's safe return, but that didn't happen.

Mishap Details

• "This is a redundant system, but because of the design flaw, the exact same flaw is repeated in both systems," Ryschkewitsch said. "In that case, redundancy does not buy you any increase in reliability."

• The same types of switches are used on NASA's Stardust comet sample return mission due back to Earth in 2006, but researchers said preliminary studies show they were installed correctly.

Wikipedia

• A first possible root cause of the failed deployment of the parachutes was announced in an October 14 press release. Lockheed Martin had built the system with an acceleration sensor's internal mechanisms wrongly oriented, and design reviews had not caught the mistake. The intended design was to make an electrical contact inside the sensor at 3 g (29 m/s²), maintaining it through the maximum expected 30 g (290 m/s²), and breaking the contact again at 3 g to start the parachute release sequence. Instead, no contact was ever made.

Genesis Mishap Investigation Board

Discussion Questions

1. Is this a ‘design’ problem ??

2. What are the performance characteristics of the g-switches ?

3. Have you ever installed a diode or capacitor backwards on a circuit board ?

4. How might this failure have shown up on an FMEA analysis ?

5. What design changes could have been made to eliminate any possible design or manufacturing errors?

Discussion Questions

• Is this a ‘design’ problem ??

– Appears to be a manufacturing problem not a design problem.

• What are the performance characteristics of the g-switches ?

– Seem to be unidirectional sensing with +/- output.

• Have you ever installed a diode or capacitor backwards on a circuit board ?

• How might this failure have shown up on an FMEA analysis ?

– If switch system fails or vehicle is in wrong re-entry orientation – vehicle crashes. Might have pointed out the need for more robust or a fully redundant backup system to deploy parachutes.

• What design changes could have been made to eliminate any possible design or manufacturing errors?

– Develop a fully redundant backup system. Install switches in several orientations to detect any braking g’s in any orientation.