# Carbon Nanocomposites in Aerospace Technology: A Way to Protect Low-Orbit Satellites
## 2 Corrosion Factors and Mechanisms in Low Orbit Environment
### In-Flight Corrosion Experiments  
More than 1000 materials were tested in flight by several space missions. Space shuttle missions (STS-5, STS-8, STS-17, STS-32, STS-41, STS-46) and satellites (LDEF, Solar Max, COMES experiment) were used to select suitable materials for future space missions [31].  
The Materials International Space Station Experiment (MISSE) project is an extensive in situ long-term study conducted by NASA to study the effect of LEO environment on various materials. The samples were mounted externally on the international space station and were subjected to the effects of LEO environment [29]. Suitcase-like trays known as passive experiment containers were exposed to the space environment on both ram and wake directions of the International Space Station. It was found that the \(AO\) erosion was two orders of magnitude grater in the ram direction than that in the wake direction due to the high impact energies in the former [41]. Some of the key results of the MISSE program are summarized in Table 1.  
An example of the recent experiments is shown in Figure 6. Here, a 2U Cubesat platform was used to prepare flight experiments to investigate the effect of exposure to space environment on different materials.  
\begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Material** & **Polymer** & **MISSE 2** & **Density, g/cm\({}^{3}\)** & **Area, cm\({}^{2}\)** & **MISSE 2** \\  & **Abbreviation** & **Mass Loss, g** & **Density, g/cm\({}^{3}\)** & **Area, cm\({}^{2}\)** & **Erosion Yield, cm\({}^{3}\)/atom** \\ \hline \hline Acrylonitrile butadiene styrene & ABS & 0.033861 & 1.05 & 3.4944 & \(1.09\times 10^{-24}\) \\ \hline Cellulose acetate & CA & 0.191482 & 1.2911 & 3.4831 & \(5.05\times 10^{-24}\) \\ \hline Poly-(p-phenylene terephthalamide) & PPD-T (Kevlar) & 0.026790 & 1.4422 & 3.5099 & \(6.28\times 10^{-25}\) \\ \hline Polyethylene & PE & 0.102760 & 0.918 & 3.5489 & \textgreater{}3.74\times 10^{-24}\) \\ \hline Polyvinyl fluoride & PVF & 0.132537 & 1.3792 & 3.5737 & \(3.19\times 10^{-24}\) \\ \hline Crystalline polyvinylfluoride w/white pigment & PVF (White Tedlar) & 0.004714 & 1.6241 & 3.4176 & \(1.01\times 10^{-25}\) \\ \hline Polyoxymethylene; acetal; polyformaldehydehyde & POM (Delrin) & 0.378378 & 1.3984 & 3.5119 & \(9.14\times 10^{-24}\) \\ \hline Polyacrylonitrile & PAN & 0.047281 & 1.1435 & 3.4768 & \(1.41\times 10^{-24}\) \\ \hline Allyl diglycol carbonate & ADC & 0.267295 & 1.3173 & 3.5392 & \textgreater{}6.80\times 10^{-24}\) \\ \hline Polystyrene & PS & 0.115947 & 1.0503 & 3.5043 & \(3.74\times 10^{-24}\) \\ \hline Polymethyl methacrylate & PMMA & 0.194588 & 1.1628 & 3.5456 & \textgreater{}5.60\times 10^{-24}\) \\ \hline Polyethylene oxide & PEO & 0.066395 & 1.1470 & 3.5591 & \(1.93\times 10^{-24}\) \\ \hline Poly(p-phenylene-2 6-benzobisoxazole) & PBO & 0.056778 & 1.3976 & 3.5526 & \(1.36\times 10^{-24}\) \\ \hline Epoxide or epoxy & EP & 0.140720 & 1.1150 & 3.5576 & \(4.21\times 10^{-24}\) \\ \hline Polypropylene & PP & 0.072357 & 0.907 & 3.5336 & \(2.68\times 10^{-24}\) \\ \hline Polybutylene terephthalate & PBT & 0.036429 & 1.3318 & 3.5619 & \(9.11\times 10^{-25}\) \\ \hline Polysulphone & PSU & 0.105948 & 1.2199 & 3.5010 & \(2.94\times 10^{-24}\) \\ \hline Polyurethane & PU & 0.057227 & 1.2345 & 3.5182 & \(1.56\times 10^{-24}\) \\ \hline Polyphenylene isophthalate & PPPA (Nomex) & 0.030549 & 0.72 & 3.5626 & \(1.41\times 10^{-24}\) \\ \hline Pyrolytic graphite & PG & 0.02773 & 2.22 & 3.5703 & \(4.15\times 10^{-25}\) \\ \hline Polyetherimide & PEI & 0.126853 & 1.2873 & 3.5352 & \textgreater{}3.31\times 10^{-24}\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Polymer erosion data from the Materials International Space Station Experiment program [42].