Search NASA⌕ Search

Engineering topics

Pitts, David E.

Publications and source records attributed to Pitts, David E..

12 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

High-Definition Television (HDTV) Images for Earth Observations and Earth Science Applications

As part of Detailed Test Objective 700-17A, astronauts acquired Earth observation images from orbit using a high-definition television (HDTV) camcorder, Here we provide a summary of qualitative findings following completion of tests during missions STS (Space Transport System)-93 and STS-99. We compared HDTV imagery stills to images taken using payload bay video cameras, Hasselblad film camera, and electronic still camera. We also evaluated the potential for motion video observations of changes in sunlight and the use of multi-aspect viewing to image aerosols. Spatial resolution and color quality are far superior in HDTV images compared to National Television Systems Committee (NTSC) video images. Thus, HDTV provides the first viable option for video-based remote sensing observations of Earth from orbit. Although under ideal conditions, HDTV images have less spatial resolution than medium-format film cameras, such as the Hasselblad, under some conditions on orbit, the HDTV image acquired compared favorably with the Hasselblad. Of particular note was the quality of color reproduction in the HDTV images HDTV and electronic still camera (ESC) were not compared with matched fields of view, and so spatial resolution could not be compared for the two image types. However, the color reproduction of the HDTV stills was truer than colors in the ESC images. As HDTV becomes the operational video standard for Space Shuttle and Space Station, HDTV has great potential as a source of Earth-observation data. Planning for the conversion from NTSC to HDTV video standards should include planning for Earth data archiving and distribution.

Robinson, Julie A.↗
NASA NTRS1992

Astronaut observations of the Persian (Arabian) Gulf during STS-45

As a result of the 1991 Persian Gulf war, between mid-January and June 1991, the Persian Gulf was contaminated with an estimated 4 to 6 million barrels of crude oil, released directly into the Gulf from refinement facilities, transhipment terminals, and moored tankers along the coast of Kuwait, and precipitated from oil fire smoke plumes. To assess the environmental impact of the oil, an international team of marine scientists representing 14 nations was assembled under the auspices of the United Nations International Oceanic Commission and the Regional Organization for Protection of the Marine Environment to conduct detailed surveys of the Persian Gulf, the Strait of Hormuz, and the Gulf of Oman, including hydrographic, chemical, and biological measurements. To supplement the field surveys and to serve as an aid in data interpretation, astronauts aboard the Space Shuttle Atlantis photographed water features and coastal habitats in the Persian Gulf during mission STS-45 (24 March to 02 April 1992). The astronauts collected 111 hand-held, color photographs of the Gulf (72 70-mm photographs and 39 5-inch photographs) from an altitude of 296 km (160 n.mi.). The photographs reveal distributions in water turbidity associated with outflow from the Shatt-al-Arab and water circulation along the entire coast of Iran and the Strait of Hormuz, coastal wetlands and shallow-water habitats, and sticks appearing in the sunglint pattern, which appear to be oil.

Ackleson, Steven G.↗
NASA NTRS1992

Earth observations during Space Shuttle mission STS-45 Mission to Planet Earth - March 24-April 2, 1992

A description is presented of the activities and results of the Space Shuttle mission STS-45, known as the Mission to Planet Earth. Observations of Mount St. Helens, Manila Bay and Mt. Pinatubo, the Great Salt Lake, the Aral Sea, and the Siberian cities of Troitsk and Kuybyshev are examined. The geological features and effects of human activity seen in photographs of these areas are pointed out.

Pitts, David E.↗
NASA NTRS1992

Analysis of video imagery of the reentry and breakup of the STS-31 external tank

Some of the major questions concerning the reentry and breakup of the STS-31 external tank (ET), which had a deactivated tumble valve, are addressed. The time of breakup, the altitude, and the geographic location of the ET at breakup were determined. The tumble rate was estimated to be between 8.59 deg and 8.84 deg/s. The ET broke up into at least 50 pieces 7 s after initial rupture.

Snyder, Michael W.↗
NASA NTRS1992

Global distribution of hand-held photographs of ocean and coastal regions taken during space shuttle missions - 1981-1991

During the first 10 years of the US Space Shuttle program, 26,736 high-quality, hand-held photographs have been acquired of the earth's ocean and coastal areas from orbit by astronauts during 40 missions. The photographs are cataloged and stored in the Space Shuttle Earth Observations Project (SSEOP) database. While the majority of photographs are of tropical and subtropical coastal areas, many open-ocean and high-latitude areas have also been photographed. The majority of space shuttle missions have permitted photographing northern hemisphere areas in daylight. As a result, the latitudinal distribution of photographs is biased toward the northern hemisphere, particularly in high latitudes. Coastal areas and islands are most frequently photographed, while photographs of central ocean areas are either infrequent or nonexistent.

Ackleson, Steven G.↗
NASA NTRS1992

Analysis of lightning flash videos from the Space Shuttle using blob and morphological techniques

Flash rates measured from the Space Shuttle range from 27.8 flashes per minute to 77 flashes per minute. The cloud is an optically thick medium which effectively scatters the energy from a lightning discharge and thereby broadens the risetime and duration of each lightning pulse. Because of the small size, spacecraft sensors with resolutions of 1 km or more are unlikely to detect the individual lightning channels. Instead, the energy from the lightning channel is scattered within the cloud, thereby broadening the apparent area. All of these measurements of lightning flash area and flash rate have involved manual manipulation and analysis of the video or film data. Only a small percentage of the Space Shuttle lightning video has been analyzed. An attempt is made to combine the use of real-time digital disk system and an automated analysis routine in order to overcome this limitation and make processing of a sequence of video frames a much less labor-intensive task.

Pitts, David E.↗
NASA NTRS1992

Space Shuttle photographic/television analysis project - An overview of image analysis techniques

The Space Shuttle photographic and television analysis project (SSPTAP) at the Johnson Space Center (JSC) is described. The films and videos of every Space Shuttle launch and landing are scrutinized for information on the vehicle's condition and performance which can only be obtained by photographic means when necessary. On-orbit video is used to assess problems. The photographic information is used with various other data sources to develop feasible scenarios for particular events. The data and methods used to analyze the state of the Shuttle launch vehicle are analyzed, and examples are given of some of the studies that have been conducted.

Dailey, Christine L.↗
NASA NTRS1991

Lightning flash mensuration using video from the Space Shuttle Columbia (STS-32)

Using the payload bay television cameras from various Space Shuttle missions, a study was performed to investigate the relationship between the size and duration of lightning flashes, though separated by 1-100 km, that appeared to be flashing in synchronization. The area, duration, and rate of propagation of the lightning in these storms was also studied. By employing the analytical methods described, the use of deinterlaced video of lightning observed from STS-32 provides the highest sampling rate ever utilized for this purpose from space (1 image each 16.7 m/sec).

Pitts, David E.↗
NASA NTRS1988

The use of a helicopter mounted ranging scatterometer for estimation of extinction and backscattering properties of forest canopies-I: Experimental approach and calibration

A helicopter-borne C-band scatterometer with the capability of collecting the backscattered power as a function of range is described. This instrument was repeatedly flown from May to September 1984 to study the microwave properties of forest canopies of aspen and black spruce in the Superior National Forest in Minnesota. The characteristics of the instrument, its calibration, the data collection, and preprocessing, are described.

Pitts, David E.↗
NASA NTRS1988

The use of a helicopter mounted ranging scatterometer for estimation of extinction and scattering properties of forest canopies-II: Experimental results for high-density aspen

An analytic expression is derived that describes the backscatter power from a semi-infinite plane parallel homogeneous canopy as a function of distance from an airborne radar. This model is fitted to observed data for a high-density aspen canopy by a modification of a technique developed by Tyapkin (1960). This inversion of the model provides unbiased estimates of the canopy extinction and backscattering parameters. An active radar calibrator located underneath the canopy provides an independent method of determining the volume extinction coefficient. The results reported indicate that the coefficients change throughout the year. A comparison of these coefficients with Eom and Funk's (1984) disk model, using measured canopy properties, shows that at C-band frequency, only a part of the scattering and absorption can be attributed to the canopy leaves.

Pitts, David E.↗
NASA NTRS1987

Estimation of biophysical properties of forest canopies using C-band microwave data

A scatterometer ranging experiment is described in which C-band data and boresight photography were collected using a helicopter so as to provide a capability to study scattering processes in forest canopies in the Superior National Forest in Minnesota. An inversion scheme is used to determine C-band volume extinction and scattering coefficients for high density aspen sites. Analysis of data through the season indicates that VV, HH, and VH volume extinction coefficients change during the year and are presumably affected by the emergence and senescence of leaves. A linear relationship was observed between sigma(0) (VV) and leaf area index for low and medium density aspen sites, but a large decrease occurred in sigma(0) for both high density sites. Calculations using the Fung disk model, which accounts only for the leaves, shows an underestimate of sigma(0) by a factor of two or three indicating that scattering by branches and soil background may be important at C-band.

Pitts, David E.↗