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Remote Sensing Practice Test — Easy Level

A free 10-question Remote Sensing practice test for Science Olympiad, written at invitational level. Every question and answer choice is listed below — correct answers and scoring are revealed when you take the timed test.

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1. Which statement best describes a passive remote sensing sensor used in climate studies?

  • A.A) It sends out microwave pulses and measures the returned signal from the surface
  • B.B) It emits laser light to map the height of ice sheets and forest canopies
  • C.C) It detects natural sunlight reflected from Earth or thermal infrared energy emitted by the surface
  • D.D) It uses radio waves to penetrate clouds and measure surface roughness

2. A researcher wants to monitor how quickly a large wildfire scar in a western U.S. forest recovers over several growing seasons using free satellite data. They need consistent land-cover information every couple of weeks at about 30 m resolution. Which satellite mission is the MOST appropriate primary data source for this project?

  • A.A) GOES-R geostationary weather satellite
  • B.B) Landsat series polar-orbiting satellites
  • C.C) GRACE gravity mission
  • D.D) ICESat laser altimetry mission

3. A Division C team is using Landsat reflectance data to compare vegetation health in two fields. For Pixel A, the surface reflectance is NIR = 0.60 and Red = 0.20. For Pixel B, NIR = 0.40 and Red = 0.30. Using the NDVI formula NDVI = (NIR - Red) / (NIR + Red), which statement best describes the relative vegetation condition?

  • A.A) Pixel A has higher NDVI and likely healthier, denser vegetation than Pixel B.
  • B.B) Pixel B has higher NDVI and likely healthier, denser vegetation than Pixel A.
  • C.C) Both pixels have NDVI values close to zero, indicating mostly bare soil.
  • D.D) Both pixels will have negative NDVI values, indicating water or non-vegetated surfaces.

4. A satellite image shows four spectral bands: blue, green, red, and near-infrared (NIR). In a standard false-color composite where NIR is displayed as red, what will healthy, dense vegetation usually look like?

  • A.A) Bright red, because vegetation strongly reflects NIR
  • B.B) Dark blue, because vegetation mainly reflects blue light
  • C.C) Bright green, because vegetation only reflects visible green light
  • D.D) Gray, because vegetation reflects all wavelengths equally

5. You are given two maps of the same coastal city: (1) a raster satellite image showing land cover, and (2) a vector map of building footprints and roads. You want to estimate which neighborhoods are MOST at risk from sea level rise using GIS. Which basic GIS operation would be the MOST directly useful for combining these datasets to find low-lying, highly developed areas?

  • A.A) Overlaying the vector building layer on the raster elevation/land cover layer
  • B.B) Converting the raster image to grayscale to enhance contrast
  • C.C) Increasing the spatial resolution of the raster by resampling
  • D.D) Stacking additional spectral bands into a hyperspectral cube

6. A glacier’s area is mapped from classified satellite images at two times. In 2015, the glacier covers 120 km². In 2020, it covers 108 km². Assuming a constant rate of change, what is the average percentage area loss per year over this 5-year period, and what does this trend indicate in the context of climate change?

  • A.A) 1.0% per year; indicates a minor change that is not clearly related to climate.
  • B.B) 1.7% per year; indicates sustained retreat consistent with regional warming.
  • C.C) 2.0% per year; indicates random variability with no clear long-term trend.
  • D.D) 2.4% per year; indicates acceleration of glacier growth due to cooling.

7. A student calculates NDVI for a pixel using satellite data: NIR reflectance = 0.7 and red reflectance = 0.3. Using NDVI = (NIR − red) / (NIR + red), what is the NDVI value and what does it most likely indicate?

  • A.A) NDVI = 0.25; sparse or stressed vegetation
  • B.B) NDVI = 0.40; healthy, relatively dense vegetation
  • C.C) NDVI = 0.80; open water or snow
  • D.D) NDVI = −0.40; bare soil or urban surface

8. A climate scientist compares two satellite images of Arctic sea ice extent: one from September 1990 and one from September 2020, both from similar passive optical sensors. The 2020 image shows a noticeably smaller bright white area of sea ice. To turn this visual comparison into quantitative climate evidence, which step is the MOST appropriate next action?

  • A.A) Measure the area of sea ice in each image using pixel counts and compare the long-term trend with additional years
  • B.B) Visually estimate the percentage change in sea ice by eye and report that value
  • C.C) Assume the difference is due to different satellite sensors and discard the images
  • D.D) Recolor the images using a different false-color scheme so the ice appears red instead of white

9. Which type of resolution is most important for a climate satellite designed to monitor the day-to-day development of hurricanes and thunderstorms over the same region?

  • A.A) Spatial resolution, so the sensor can distinguish very small features on the ground
  • B.B) Spectral resolution, so the sensor can measure many narrow wavelength bands
  • C.C) Temporal resolution, so the sensor can revisit the same area very frequently
  • D.D) Radiometric resolution, so the sensor can detect tiny differences in brightness levels

10. You receive NDVI data from a satellite over an agricultural region for June in two different years. Field A has an average NDVI of 0.75 in Year 1 and 0.40 in Year 2, while neighboring natural grassland shows NDVI values that are nearly the same both years. Assuming the same sensor and processing were used, which is the MOST reasonable interpretation related to climate conditions?

  • A.A) Field A likely experienced more drought or crop stress in Year 2, while the natural grassland was relatively unaffected
  • B.B) Field A must have changed from vegetation to bare soil in Year 2, so NDVI should be negative
  • C.C) The grassland data prove that NDVI cannot be used to detect drought impacts on vegetation
  • D.D) The lower NDVI in Field A in Year 2 must be caused by switching to a radar sensor instead of an optical sensor

Questions are AI-generated for Remote Sensing practice and can contain mistakes — check answers against reliable sources. Take the timed version to see correct answers, scoring, and explanations: start the Remote Sensing test.