Impact Images
Space Shuttle
Some of the largest micrometeoroid and orbital debris impacts observed on the space shuttle radiator panels, windows, and wing edges are shown below. These are just a small subset of the thousands of impacts collected between the STS-50 and STS-135 missions. Post-flight damage inspections were generally limited in time available for inspection and to these three orbiter surface areas because MMOD impacts are easier to visually detect on these surfaces.
STS-118 Left-Hand Radiator No. 4
Based on impact tests and elemental analysis of the impact entry hole, an estimated 1.6mm diameter orbital debris particle traveling at about 9 kilometers per second left this 6mm diameter entry hole and punched completely through the radiator and down to the payload bay door structure.
STS-115 Right-Hand Radiator No. 4
This is a view of the STS-115 right-hand side radiator #4 MMOD hit. This image shows a close up of the entry hole into the radiator panel. Based on analysis of the entry hole residue and impact testing, the impactor was possibly a piece of electronic circuit board material. Estimated diameter of this debris particle was 1.2mm impacting at about 9 kilometers miles per second.
STS-133 Right-Hand Radiator No. 2 Sample No. 37
Analysis was unable to identify the impactor material, but it’s suspected that an aluminum orbital debris impactor measuring about 0.2mm diameter caused this 0.6mm hole in the radiator. The damage to the outer plastic covering is about 5mm and is unusually much larger than the central hole.
STS-128 Left-Hand Radiator No. 1
One of the most noteworthy radiator impacts – "the doubler hit" on STS-128 – proved that earlier MMOD protection added to the radiator not only was needed, but worked well. The doubler – a thin metal strip – was placed over each radiator tube to act as extra shielding against impacts. Early assessments in the late-1990s showed this was needed to protect the shuttle cooling system. Impact simulations of this event clearly show the radiator coolant tube would have been punctured and leaked. The doublers and coolant isolation valves installed earlier kept this impact from ending the STS-128 mission early.
STS-128 Left-Hand Radiator No. 4
Due to the presence of chromium, iron, and titanium in the impact residue around the entry hole, we think this was caused by a small paint flake about 0.3mm that hit the radiator at about 10 kilometers per second. The hole measures about 1.2mm diameter and the larger circular "tape hole" measures about 4.6mm in diameter.
STS-122 Right-Hand Radiator No. 3 Sample No. 28
This impact barely punctured the outer layer of the radiator, but the shape of the spray pattern suggest an impact direction and angle. Analysis of impactor residue yielded iron, chromium, nickel – probably a steel particle – estimated to be about 0.2mm in size.
STS-123 Right-Hand Radiator No. 1
This hole measures approximately 1mm across. Residue around the hole was analyzed for impactor residue, but was not determined. Note that many orbital debris particles are made of aluminum. Aluminum orbital debris impacts on aluminum radiator panels make it difficult to determine what the impactor material and origin.
STS-121 Right-Hand Radiator No. 1 Sample No. 6
Residue around this 1mm diameter hole was analyzed for impactor residue. Due to the presence of carbon fiber and silicon, it is estimated that this impactor was orbital debris and may have been about a 0.3mm diameter piece of the plastic used for electronic circuit boards.
STS-128 Nose Cap
Size: 2.9mm x 1.8mm
Depth: 0.29mm
Evaluated Particle Type: orbital debris
Particle Elements: tin, copper-zinc, titanium, silicon-oxide, bismuth, silver
Estimated Particle Size: 0.06mm
Estimated Velocity: 10 kilometers per second
Notes: Seen while on orbit during inspection of high-heat surfaces using remote controlled camera
Depth: 0.29mm
Evaluated Particle Type: orbital debris
Particle Elements: tin, copper-zinc, titanium, silicon-oxide, bismuth, silver
Estimated Particle Size: 0.06mm
Estimated Velocity: 10 kilometers per second
Notes: Seen while on orbit during inspection of high-heat surfaces using remote controlled camera