Velocity Perturbations Analysis of the Spot 1 Ariane Rocket Fragmentation

Abstract

The breakup of the Spot 1 Ariane third stage rocket was one of the most prolific and puzzling satellite fragmentation events ever. The cause of the breakup was long listed as unknown, with several studies pointing to different conclusions. This study re-examines the breakup by studying the velocity distribution patterns of the fragments. The presence of six fragments in high energy orbits suggests collision as a possible cause of the breakup. The existence of butterfly patterns in the spread velocities of the fragments in planes between the vertical and the downrange directions also points to fragmentation by impact. The orientations of the debris concentrations flanking the high energy ricochet uncovers the possible path of the projectile that could have struck the Ariane rocket—the projectile could have come from an angle of 11° or less above the horizontal and about 6° from the left of the Ariane’s path. The velocity perturbations distributions in the radial and downrange components show that fragments lying outside the Gaussian envelopes comprised the high energy ricochet and ejecta which emanated from the contact area. Both of the Gaussian envelopes exhibited displacements opposite from the ricochet and ejecta, thus betraying recoil effects. The cross-range velocity distribution pattern was severely distorted with the ejecta forming concentrations on either side of the Gaussian envelope—a further sign of possible collision. Finally, a cluster analysis of the fragments indicates that the vast majority of the fragments suffered only small velocity changes while the high energy ricochet and ejecta formed their own distinct clusters, which is yet another indication of possible fragmentation by impact. The possible path of the projectile would place itself among the members of the Sun-synchronous orbiting group.