What is an orbit? (think very generally)

the repeating path that one object takes around another

What is an orbit cycle?

The interval of time required for a satellite to pass a point on Earth’s surface directly below the satellite for a second time.

What is revisit time?

The interval of time between observations of the same point on Earth by a satellite

Why can the revisit time of a satellite differ from its orbit cycle?

because satellites can look off-nadir and therefor pass a point twice without imaging it both times.

What is a Geostationary Orbit?

An orbit that matches the speed and direction of
Earth’s rotation and therefor appears to be stationary over a fixed position of the earth.

What would be some uses of a satellite in geostationary orbit (2)

Continuous data collection over one location for weather, communication satellites

Decreasing the revisit time of a satellite _____________ the temporal resolution of its images. Geostationary satellites have a ________ temporal resolution.

decreases, high

What is a near-polar orbit?

An orbit path close to the North and South Poles

What is a sun-synchronous orbit? What is the advantage of this?

An orbital path set so the satellite crosses the
same area at the same local time. Consistent illumination conditions in each season, reduces the variables between images to provide more accurate comparisons.

What is a satellite swath?

The width of the ground area a satellite images

What is an Across-track scanner? What is the other name it's referred to as?

A scanning method that uses a rotating mirror to collect data by moving back and forth, also referred to as a whiskbroom scanner.

What is an Along-track scanner? What is the other name it's referred to as?

A scanning method that uses a linear array to collect data directly on a satellite’s path, also referred to as a pushbroom scanner.

What is relief displacement?

When objects towards the edge of an image appear to lean away from the centre of the image

What is Tangential scale distortion?

The compression of image features located further away from nadir

What is Off-Nadir viewing?

The capability of a centre to look off nadir

What do we use to track satellites?

Receiving stations

The U of L Satellite Receiving Station is owned by which company currently?

Planet labs

What is the spatial resolution of a satellite?

The smallest unit of area the sensor can collect
information about

What is the Radiometric resolution of a satellite?

The sensor’s ability to determine fine
differences in a band of energy measurements.

What is the Spectral resolution of a satellite?

The number and width of bands measured by a
sensor.

What is the Temporal resolution of a satellite?

The revisit time, or time between images in the
same location.

___________ has over _____ years of continuous monitoring and is considered the gold standard due to its quality data and longevity.

Landsat, 50

When was Landsat 1 launched?

1972

With which satellite did Landsat switch from across track to along track sensors?

Landsat 8

Landsat satellites have progressed from ___ bit with Landsat 1 to ___ bit with Landsat 8 and 9.

6 bit, 12 bit

A _______________ sensor measures one broad range of wavelengths

Panchromatic

What is pansharpening?

The process of merging high-resolution panchromatic and lower resolution multispectral imagery to create a single-coloured image

What does SWIR stand for? What does NIR stand for?

SWIR = short wavelength infrared

NIR = near infrared

What broke on Landsat 7 that corrected for forward motion?

The Scan Line Corrector (SLC)

What are the two new bands added to Landsat 8 and 9? What are they used to detect?

Band 1: ultra-blue- to detect chlorophyl concentrations (ocean colour) in coastal
regions and for aerosol detection

Band 9: cirrus band- to detect cirrus clouds by measuring reflected NIR energy

________ is the 2nd longest-running Earth Observation mission (37 years) but has a ________________ orientation instead of an experimental one.

SPOT, commercial

SPOT is capable of off-nadir viewing which
creates image ____________ and allows for the creation of which type of model?

parallax, digital elevation models

SPOT orbits the world from pole to pole and revisits points on earth at the same local time each time it passes over them. Which two terms apply to SPOT's orbits?

Near-polar and sun-synchronous

Sentinel, operated by the European Space Agency (ESA), has three main uses. What are they?

Land Monitoring (information on land cover like vegetation state and the water cycle), Emergency management (information for the management of natural disasters, man-made emergency situations and humanitarian crises), and Security (border and maritime surveillance)

Why was the company Digital Globe revolutionary?

They produced the first public collection of high-resolution imagery that rivalled military technology with the satellite IKONOS-2.

Why was the company WorldView revolutionary?

They produced the world’s first 50 cm resolution commercial satellite.

What is the goal of Maxar’s WorldView Legion?

To support US national security through surveillance and monitoring

Planet labs has three satellite types that make up their constellation. What are they?

• Dove
• RapidEye
• SkySat

Why were Dove satellites so different in a practical sense from the norm of the time? (2)

• Size, 10 X 10 X 30 cm and weigh about 10 lbs
• Many can be launched at the same time

Of the three satellite types that made up the Planet labs constellation which was retired?

RapidEye