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Artist’s rendition of satellites orbiting the Earth – rottenman/123RF Stock Photo

Today we’re looking at the Earth Observation (EO) satellite launches expected this week, together with a shout-out to one of the longest datasets in the industry!

SpaceX Launches

Note: The expected launch of the two WorldView-Legion satellites detailed below did not go ahead. There is currently no planned launch date available.

The long-awaited launch of the first pair of WorldView-Legion EO satellites is due to take off later today from the Vandenberg Space Force Base in California on the SpaceX Falcon 9 rocket. The satellites were due to be launched originally in April last year, and again in June, and finally last week. Hopefully, they will be put into orbit at an altitude of 450 kilometres.

WorldViewLegion-1, and -2, were built, and will be operated, by Maxar. They are both carrying a WorldView Legion Camera, which is a very high resolution optical imager with 9 spectral wavebands – two blue wavebands, one green, one yellow, three red, and one near-infrared offering a spatial resolution of 1.16 metres; together with one panchromatic band offering a spatial resolution of 29 centimetres. The swath width for all bands is three kilometres.

These are the first two of a six-strong constellation, which will eventually replace the existing WorldView-1, WorldView-2 and GeoEye-1 EO satellites. The data is expected to be used for environmental sustainability, disaster response, and national security applications.

Rocket Labs Satellite Launches

Wednesday 24^th April could be a very popular EO launch day as it’s when the window for Rocket Lab’s next mission also opens. The mission, called The Beginning of the Swarm, is scheduled to take off from New Zealand onboard the Electron rocket. There will be two payloads:

• NeonSat-1 is a high resolution optical EO microsatellite developed by a consortium of the Korea Advanced Institute of Science and Technology (KAIST), the Korea Aerospace Research Institute, and Satrec Initiative; which should be taken put into an orbit of approximately 500 kilometres. It will offer both multispectral and panchromatic modes, with the multispectral mode offering a spatial resolution of 4 metres, while the panchromatic mode resolution is 1 metre. Neonsat-1 is a prototype, and if this launch is a success, it is expected that five further satellites will be launched in 2026, and a further five the following year to create a constellation of eleven, with the satellites operating in various orbital planes to enable more frequent observations of the Korean Peninsula. It is focused on monitoring natural disasters using artificial intelligence.
• ACS3 is a technology demonstration satellite developed by NASA to test deployable structures for solar sail propulsion systems that use sunlight to propel the spacecraft.

Shout-out To The OG!

Finally, while we frequently talk about the latest EO satellite to go into space, or plans for the next big constellation, it is also worth reflecting on those satellites that have been there and done it for EO. Today, we want to recognise Landsat – in particular, Landsat-7 which last week celebrated twenty-five years in space!

Landsat 7 was launched on the 15^th April 1999 from the Vandenberg Air Force Base in California onboard on a Delta II rocket. Landsat-7 carried the Enhanced Thematic Mapper Plus (ETM+) instrument with six spectral bands offering a spatial resolution of 30 metres, together with a panchromatic band offering 15 metres spatial resolution. The satellite has had its problems as its scan line corrector failed on the 31^st May 2003, causing parts of the swatch edge not to be mapped resulting in black stripes of missing data in affected images. Despite this issue, around 78% of the image was still usable and, as discussed in last week’s blog on flamingos, still offered valuable data!

The satellite has orbited the planet over 130,000 times and collected over 3 million images as part of a dataset going back over sixty years! The imaging function of Landsat-7 was stopped in January of this year due to full sunlight exposure, which caused issues with the batteries. However, the satellite is still in orbit!

Conclusion

As new satellites are launched so regularly, it can be easy to think of EO as a new and emerging sector; but it is worth remembering some datasets have long and proud history and there is some age to our industry.