## 2 Literature Review
### Discussion
#### Challenges  
Aside from the cost aspects, the obvious bottleneck of wildfire observation using satellite technology is optimizing the area covered with the frequency of data collection. The high-flying altitudes limit the resolving power of fires smaller than a pixel in the images, which can make identification of young fires extremely difficult. Dense clouds and smoke cover can severely reduce ground visibility to even IR and, therefore, adversely impact their utility for tracking active fires under such conditions. Until the end of the 20 th century, this technology was available only to a few niche organizations, due to high mission cost and limited capacity for onboard systems. Although CubeSats project have largely addressed this issue, launching a CubeSat network is still expensive compared to other methods discussed in this paper. Currently, the cheapest option is Interorbital Systems (IOS) TubeSatsatellite kits, at about USD 16,000 (academic pricing) and USD 32,000 (commercial pricing) for a 1U kit, including launch. The price for a single 3U kit with inclusive launch services is USD 36,480 (academic pricing) and USD 72,960 (commercial pricing) [99].  
\begin{table}
\begin{tabular}{l c c} \hline \hline
**Instrument** & **Notes** & **Launch Date** \\ \hline Airborne Visible/Infrared & \(\bullet\) & Optical sensor images 224 spectral bands between 400–2500 nm \\ Imaging & \(\bullet\) & Assesses fuel availability and condition, and stage of the fire \\ Spectrometer (AVIRIS) [100] & \(\bullet\) & Carried by ER-2 jet, WB-57, Twin Otter International’s \\  & Turboprop, etc. \\ Advanced Very High-Resolution & \(\bullet\) & Measures data in six channels in 0.6 \(\upmu\)m–12 \(\upmu\)m range \\ Radiometer (AVHRR) & \(\bullet\) & Records land surface temperature, fire \\ (NOAA) [101] & \(\bullet\) & temperatures/expanse/radiative power \\  & \(\bullet\) & Records images in 14 wavelengths between visible to thermal \\  & IR, including VNIR, SWIR and TIR bands & \\ Advanced Spaceborne Thermal & \(\bullet\) & Captures high resolution images and surface temperature \\  & Emission and Reflection & of Earth \\ Radiometer (ASTER) [102] & \(\bullet\) & Helps track smokes and active fires \\  & \(\bullet\) & Carried by Terra \\  & \(\bullet\) & Records 36 spectral bands data between 0.4 \(\upmu\)m–14.4 \(\upmu\)m \\ Moderate Resolution Imaging & \(\bullet\) & Monitors fires and hot spots through visible and IR imaging \\ Spectroradiometer (MODIS) [103] & \(\bullet\) & Carried by Terra and Aqua \\  & \(\bullet\) & Nine cameras gather RGB-IR data from different angles \\  & \(\bullet\) & tracks smoke plume and concentration of smoke particulates \\ Multi-angle Imaging & \(\bullet\) & 18 December 1999 \\ SpectroRadiometer (MISR) [104] & \(\bullet\) & Tracks wildfires \\  & \(\bullet\) & Carried by Terra \\  & \(\bullet\) & Measures IR radiation between 4.7 \(\upmu\)m–2.4 \(\upmu\)m wavelengths \\ Measurement of Pollution in the & \(\bullet\) & tracks emission and movement of carbon monoxide globally, \\  & \(\bullet\) & and emission contributions from fires \\  & \(\bullet\) & Carried by Terra \\  & \(\bullet\) & Tracks global movement of greenhouse gases, including \\  & \(\bullet\) & emission from fires, and IR mapping of Earth’s surface \\ Atmospheric Infrared Sounder & \(\bullet\) & Helps understand impact on weather patterns, climate change \\ (AIRS) [106] & \(\bullet\) & and forecast droughts \\  & \(\bullet\) & Carried by Aqua \\  & \(\bullet\) & Uses 532 nm and 1064 nm LIDAR \\ Cloud Aerosol Lidar with & \(\bullet\) & Tracks smoke plumes and aerosol concentrations, focusing on \\ Orthogonal Polarization & \(\bullet\) & Carried on CALIPSO \\ (CALIOP) [107] & \(\bullet\) & CALIPSO also has a 645 nm widefield camera, infrared \\  & \(\bullet\) & radiometers (8.65 \(\upmu\)m, 10.6 \(\upmu\)m, 12 \(\upmu\)m) to assist in data collection \\ \hline \hline \end{tabular}
\end{table}
Table 2: NOAA and NASA satellites that help in wildfire detection, tracking and for studying its global impacts on climate and pollution.