Module 1 Assessment Flashcards
(30 cards)
Question with image
Match each fundamental RS resolution with its correct brief definition:
Spatial Resolution
Spectral Resolution
Angular Resolution
Temporal Resolution
Radiometric Resolution
———————————-
- Physical size of pixels in resulting imagery
- Number and width of EV wavelength portions measured by a sensor
- The number of different angles the same place is observed at (near)simultaneously
- The revisit frequency, or how long between subsequent observations of the same place
- The number of different brightness levels distinguishable by the sensor
Spatial Resolution → Physical size of pixels in resulting imagery
Spectral Resolution → Number and width of EV wavelength portions measured by a sensor
Angular Resolution → The number of different angles the same place is observed at (near)simultaneously
Temporal Resolution → The revisit frequency, or how long between subsequent observations of the same place
Radiometric Resolution → The number of different brightness levels distinguishable by the sensor
Which of the following is a characteristic of a system conducting active vs passive remote sensing?
a. Measures the ultraviolet energy from the sun that is reflected by Earth back into space
b. Measures the intensity of microwave emissions from the Earth itself
c. Measures the thermal wavelength radiation emanating from Earth (i.e., temperature)
d. Measures the EM energy reflected from Earth from a pulse created by the sensor itself
d. Measures the EM energy reflected from Earth from a pulse created by the sensor itself
What is the orbital period of a hypothetical satellite orbiting Earth at an altitude of 1825 km (round to the nearest whole number)?
a. 123 minutes
b. 0.02 seconds
c. 13 minutes
d. 84 minutes
a. 123 minutes
Of the more than 7000 satellites currently tracked by the UCS, about how many have Earth Observation (EO) as their primary mission?
a. More than 1000
b. 643
c. less than 50
d. Nearly all of the >7000 have EO missions
a. More than 1000
Which of the following is an example of an active remote sensing technology?
a. MODIS measures 36 different spectral wavelengths of EM radiation reflected off Earth from the sun, enabling a wide suite of terrestrial and marine applications
b. Landsat 8’s OLI instrument measures infrared radiation from the sun that is reflected by Earth, enabling the measurement of chloroplast abundance
c. The GEDI instrument aboard the ISS uses a lidar instrument to measure the height and vertical distribution of tree biomass on Earth
d. GOES-16 is a meteorological satellite that can image an entire hemisphere of Earth every 5 minutes. It measures visible wavelengths of reflected sunlight as well as several narrow infrared bands to measure atmospheric water vapor
c. The GEDI instrument aboard the ISS uses a lidar instrument to measure the height and vertical distribution of tree biomass on Earth
Which characteristic is most associated with hyperspectral sensors?
a. 10s to 100s (or more) spectral bands
b. A very distant orbit
c. Are mostly used for monitoring the weather
d. The highest signal-to-noise ratio
a. 10s to 100s (or more) spectral bands
The ISS orbits at about 400 km above Earth, what is its approximate orbital velocity?
a. 7,910 m/s
b. 7,670 m/s
c. 31,410 m/s
d. 242,557 m/s
b. 7,670 m/s
Which of the following is not among the discoveries enabled by the Landsat program?
a. Measuring the rapid retreat of glaciers in the Chugach Range of Alaska
b. Illegal gold mining, leading to mercury poisoning of wildlife in people in the Amazon
c. Reduction in local gravity in the Indogangetic Plain resulting from ground water pumping
d. Ecosystem recovery dynamics following natural disasters
c. Reduction in local gravity in the Indogangetic Plain resulting from ground water pumping
Landsat cannot make measurements of local gravity, and so would not be able to measure subsurface water mass. However, the GRACE satellites are able to make this type of measurement and have indeed made this discovery
Which of the following is not a reason that the Landsat program has been valuable to science
a. Landsat’s hyperspectral sensor system allows for the identification of particular plant species
b. The spatial resolution and spectral bands of Landsat are well chosen for studying terrestrial phenomenon like land cover/use change, deforestation, and agriculture
c. The Landsat archive provides a 50 year record of highly consistent Earth imagery
d. The Free and Open data access policy, which began in 2008, made the imagery free to everyone in the world and ushered in a new era of applications and techniques for moderate resolution remote sensing
a. Landsat’s hyperspectral sensor system allows for the identification of particular plant species
Which of the following is true of the Landsat series of satellite sensing systems?
a. Were originally a US Air Force project designed to map and monitor Soviet missile silos
b. The most recent versions of Landsat sensors (OLI and OLI+) are active, synthetic aperture radar (SAR) sensors
c. Have been deployed in geostationary orbits (GEO) because they are mostly used to track meteorological phenomenon
d. The sensors have evolved in terms of spatial and spectral resolution, but have maintained consistency that enables scientific comparison of images collected by different sensors
d. The sensors have evolved in terms of spatial and spectral resolution, but have maintained consistency that enables scientific comparison of images collected by different sensors
Many EO satellites operate in LEO orbit, around 700 km above Earth. About how long does it take these satellites to complete one orbit around Earth?
a. 5924 minutes
b. 9.8 minutes
c. 24 hours
d. About 99 minutes
d. About 99 minutes
An Earth observing satellite’s orbital speed is determined solely by its:
a. Spatial resolution
b. Launch vehicle
c. Swath width
d. Altitude
d. Altitude
Which of the following satellite orbits would be the best choice for a sensing system designed to monitor hurricanes and other large-scale meteorological phenomena?
a. A very low and high-velocity orbit such as the one used by the International Space Station (about 400 km)
b. Geostationary orbit (GEO), about 36,000 km away
c. A highly elliptical orbit with an apogee over the North pole
d. Low Earth orbit (LEO), about 700 km away
b. Geostationary orbit (GEO), about 36,000 km away
Yes, this will ensure that it’s always monitoring the same place
Seeing Earth in its entirety, like in the Apollo astronaut photographs, created pyschological effects characterized by feelings of awe, fragility, and connectedness. This phenomenon has come to be known as the:
a. Fermi Paradox
b. Gaia Hypothesis
c. Stockholm Syndrome
d. Overview Effect
d. Overview Effect
The Silicon Valley company, Planet (formerly Planet Labs), offers high resolution (3-5 m pixel sizes) multispectral imagery of nearly the entire Earth everyday. How are they able to overcome the resolution tradeoff and offer products with high temporal AND high spatial resolution?
a. They have a constellation of hundreds of satellites. Each individual satellite has high spatial resolution, but relatively low temporal resolution. However, in combination, the constellation can “see” most everywhere on Earth at least once a day.
b. Planet’s Doves are in a lower orbit than other sun-synchronous LEO satellite systems, and thus they orbit faster and can use less powerful telescopes to achieve higher resolution.
c. Planet combines all other LEO satellite sensor observations, like Landsat, Sentinel-2, MODIS, etc. into a higher resolution, higher temporal resolution product using advanced machine learning techniques like adversarial generative AI and convolutional neural networks.
d. They have engineered very advanced sensor technology using quantum principles. When combined with their innovative multiresolution telescope system, they are able to overcome the spatial-temporal resolution tradeoff
a. They have a constellation of hundreds of satellites. Each individual satellite has high spatial resolution, but relatively low temporal resolution. However, in combination, the constellation can “see” most everywhere on Earth at least once a day.
Yes, the tradeoffs we mentioned are limited to a single-sensor systems. Planet overcomes this by having hundreds of microsatellites
Question with image
Which of the following has the lowest orbital velocity?
a. The Landsat series of satellites at an orbital height of ~700 km above Earth
b. Satellites in the GPS constellation orbiting at ~20,000 km above Earth
c. A geostationary satellite orbiting ~36000 km from Earth
d. The ISS (International Space Station) orbiting at ~400 km above Earth
c. A geostationary satellite orbiting ~36000 km from Earth
d is incorrect - The further away from Earth, the slower the orbital velocity. So, in this case, the GEO satellite 36,000 km away has the slowest orbital speed
If a researcher wanted to make a map of different types of plant communities across a large area, which of the following RS resolutions would be most important to maximize?
a. Spatial resolution
b. Temporal resolution
c. Angular resolution
d. Spectral resolution
d. Spectral resolution
While we would need the spatial resolution to be as small or smaller than one of our plant communities, maximizing the spectral resolution is the best answer here. That is because, regardless of the spatial resolution, we’d be unable to distinguish different species/communities at all without being able to discriminate subtle differences in their spectral response
A researcher is interested in making a map of the water turbidity in the Gulf of Mexico for a single snapshot in time. Which of the following RS resolutions would be most important to maximize in this application?
a. Spatial resolution
b. Radiometric resolution
c. Spectral resolution
d. Temporal resolution
b. Radiometric resolution
Yes, water is very dark and so being able to discriminate many different levels of brightness would be paramount when mapping water turbidity
A researcher is interested in how tropical cyclones evolve, which RS resolution would be most helpful to maximize in this application?
a. Radiometric resolution
b. Temporal resolution
c. Spatial resolution
d. Spectral resolution
b. Temporal resolution
Yes, having high temporal resolution is essential because cyclones develop and change hour-to-hour
Which of the following is uniquely true of satellites in a sun-synchronous LEO orbit?
a. They will collect observations of a place at different times during the day, allowing for the characterization of diurnal processes
b. Exclusively use along-track scanning systems in order to mitigate against failures
c. They will always image a certain place at the same local solar time.
d. The will revisit the same place on Earth every 16 days
c. They will always image a certain place at the same local solar time.
It is commonly accepted that the “Space Race” between the United States and the Soviet Union started and ended with which events?
a. Goddard’s development of liquid fuel rockets and establishment of the International Space Station
b. End of WW2 and Apollo 11’s successful lunar landing
c. End of WW1 and the launch of Sputnik
d. The launch of Sputnik and Yuri Gagarin’s first orbital flight
b. End of WW2 and Apollo 11’s successful lunar landing
Evaluate the accuracy of this statement: An across-track, or whisk broom, scanner is less prone to failure because it does not include moving parts, such as a rotating scan mirror.
False
