Launch vehicles impart large shocks to spacecraft due to several flight events during ascent to orbit. These events include:

• Motor ignitions
• Motor shutdowns
• Stage separations
• Fairing separations
• Payload separations
• Structure-borne acoustics

In order for the spacecraft to survive such a trip to orbit, one of two choices must be made: (1) design all structure, payloads, and systems on the spacecraft to be strong enough to survive the high frequency and shock loads, or (2) reduce the magnitude of the these loads. The former is not a good choice because it typically requires additional cost, schedule, and weight. The latter is the preferred choice because it allows the focus of the spacecraft design to be primarily for on-orbit performance rather that for launch survival.

CSA Engineering is currently involved in the design and development of whole-spacecraft shock isolation systems. These systems are inserted between the launch vehicle and the spacecraft and will serve to attenuate structure-borne high frequency and shock launch loads imparted to the spacecraft.

The anticipated benefits of CSA's whole-spacecraft shock isolation systems include:

• Significant attenuation of shock events
• Shock-isolate entire spacecraft
• Relatively small and lightweight structure
• Very low risk
• Very high reliability
• Insignificant reduction of spacecraft rocking modes
• Insignificant loss-of-clearance

Shock testing at CSA.

PSD waterfall plots of the Taurus/STEX flight data show the frequency content as a function of time. From these plots it is clear that the SoftRide vibration isolation system performed very well to reduce structure-borne vibration levels transmitted to the spacecraft. The isolation system was designed specifically to reduce the effects of solid motor resonant burn in the 45 Hz to 60 Hz frequency range, which it did very well. It should also be noted that the SoftRide vibration isolation system provided extreme reductions of structure-borne acoustics at higher-frequencies as shown in the plots up to 2000 Hz.

The plots to the left look great on a larger scale. Click on the thumbnail image below to view the larger version:

Data is shown from a component-level shock test of the SoftRide isolation system that was flown on the Taurus/GFO mission. This data shows excellent shock attenuation from 100 Hz and upward. This concurs with the flight data that shows excellent attenuation of structure-borne acoustics.