## 2 UAS Platform Types and Characteristics
### Characteristics and Examples of UAS Categories
#### 2.2.4. MALE UAS

Table 1: Summary of Western (US) States Fire Mission (WSFM) flights, 2006–2009. Figure 8: NASA Ikhana. Image courtesy NASA. October 2007 firestorms that caused extensive damage, evacuations of \(\sim\)500,000 people, and considerable loss of life. During that mission period (over five days) the Ikhana was granted access to airspace over densely populated regions of southern California, an event never before allowed by the FAA. Ikhana flew at a constant altitude of FL230 (7,000 m), under constant control of a NASA pilot through some of the world's busiest airspace, supporting image data collection over 11 wildfires near San Diego and Los Angeles metropolitan areas. This mission series opened the door for greater UAS capabilities within the remote sensing data collection community and demonstrated the safe operations of larger UAS in support of regional assessments of environmental conditions. The NASA Altus II UAS was a modified General Atomics Gnat-750 used as the platform for the Altus Cumulus Electrification Study (ACES), which investigated thunderstorms in Florida, USA, in 2002. ACES investigated the relationship between storm electrical activity and storm morphology, and validated satellite-based lightning measurements. ACES also demonstrated the utility and promise of UAV platforms for Earth science. The payload included sensors to characterize lightning activity and the electrical environment near thunderstorms, contributing electrical and optical observations unavailable from other sources. The Altus's endurance allowed flights near and over thunderstorms for long periods of time that allowed investigations to be conducted over entire storm life cycles [13]. The NASA Sensor Integrated Environmental Remote Research Aircraft (SIERRA) is a MALE-class, unmanned aircraft system (UAS) that can perform remote sensing and atmospheric sampling missions in isolated and often inaccessible regions (Figure 9). Designed by the US Naval Research Laboratory and developed at NASA's Ames Research Center, the 180 kg (gross takeoff weight) SIERRA can carry a 45 kg payload on flights lasting up to 10 hours, at a maximum altitude of 3,600 m and at airspeeds of 100 km/h. The SIERRA has supported several airborne science data collection campaigns, including the following missions:  
* CASIE (2009): The Characterization of Arctic Sea Ice Experiment operated from Svalbard, Norway, above the Arctic Circle. The CASIE experiment focused on measurement of sea-ice  
Figure 9: The NASA SIERRA, shown flying near Svalbard, Norway, 2009. Image courtesy NASA. roughness via remote sensing to try to detect basic changes in ice conditions such as thickness and ice age and other factors;
* RAM-GGM (2011): The Right-of Way Automated Monitoring-Greenhouse Gas Mission pilot study occurred in Railroad Valley, NV, USA, with the focus to test bed instruments for autonomously detecting and locating methane releases from petroleum production, extraction sites and distribution networks. The missions in June 2011 with a Cavity-Ring Flux Analyzer onboard the SIERRA aircraft were successful in mapping methane levels in the lower atmosphere above a variety of locales in Railroad Valley;
* Long-Term Earthquake Hazards and groundwater measurement UAS (SIERRA) campaign (2011-2013): The SIERRA platform is being used to characterize seismic hazard potential and map paths for groundwater flow using high resolution magnetic field data collections along faults and fractures in otherwise inaccessible terrain in the western US (Oregon and California). * High Resolution Assessment of Carbon Dynamics in Seagrass and Coral Reef Biomes (2011-2013): This SIERRA UAS mission focuses on hyperspectral bio-optical observations to assess core physiological and biogeochemical variables in seagrass and shallow tropical coral habitats. The primary SIERRA mission areas are the areas around Cedar Key, FL, USA, and Buccal Reef, Tobago (Caribbean Sea). The use of MALE platforms is appropriate when data collection is required at regional scales and at altitudes common to manned aircraft.