Tag: Resources

If you’re a frequent user of Terra data, you’re probably somewhat aware of the recent and upcoming changes to Terra’s “traditional” orbit. (If you weren’t aware of these upcoming changes, or if you just want to read an excellent overview of Terra’s legacy and future, click on the link to read Blumenfeld’s article “From Terra to Terra Firma”).

In efforts to get the news out about Terra’s lowering and drift – and to inform users of potential data impacts resulting from these orbit changes — we’ll be posting several new infographics and short animations on the Terra website, as part of a larger campaign to celebrate over two decades of Terra data. Any graphics posted are available for public use and redistribution. (Click on the image for larger resolution and please share with others!)

Here’s an example of the new graphics we’ll be posting on the site:

Drifting: For over 20 years, Terra has shared an orbital path above the earth with a group of other polar-orbiting, earth-watching satellites (aka Terra's satellite constellation). Terra also passes over the equator at the same time every day. But how does Terra maintain its altitude and speed when Earth's gravity is constantly pulling on it? The answer: by burning fuel to counteract the drag! But Terra's also getting older (in satellite years) and is almost out of fuel; so since 2020, the satellite has been drifting, with no burns to counter the drag, causing slight increases in orbit speed and a resulting earlier passover time each day. DATA IMPACTS: Minor. Data is collected <15 minutes earlier each morning. Slight changes to surface shadows and data swath edges.

Constellation Exit: In October 2022, Terra will be lowered about 4 miles out of its constellation group's path (to make room for new missions) BUT will continue drifting and collecting data in an orbit that's closer to Earth. DATA IMPACTS: Slight to minor. Terra will be even closer to earth, so the images will be collected even earlier in the morning (>15 min) and will have more detail, with only slight changes to swath margins.

Passivation: Terra will keep collecting data until HQ begins the passivation process (aka turning off the satellite's power), sometime within the next 3 to 5 years.
Timeline showing important dates and upcoming orbit changes for the Terra satellite.

This infographic gives a simplified overview of Terra’s orbital movements, from its current drift, through the constellation exit this Fall, and finally into a lower, drifting orbit – along with the estimated (minor) effects possible due to these orbital changes. 

Check the Terra website often for additional information on the Celebrating 25 Years of Terra Data campaign and events!