Orbital Focus - International Spaceflight Facts and Figures
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Tyneside, UK
2024 Jul 24
Wednesday, Day 206

Curated by:

OTV-6 Navigation Warnings

Prior to planned launch of the sixth mission for an X-37B (OTV-6), NOTAMs and Maritime Navigation Warnings were issued for areas off the east coast of the United States. Separately, a Maritime Navigation Warning was issued for an area in the Indian Ocean to be used for disposal of the Atlas V launch vehicle upper stage. The warnings covered May 16 with a backup date May 17.

Orbital Inclination

Using three of the areas indicated, it is possible to construct a model of the spaceplane's first circuit of the Earth. It tells us that the target inclination is about 44°.6. It doesn't help with the orbital altitude because the time between launch and the Atlas V re-entry is less than one hour and the track fits any height up to 500 km, or even more.

Post Launch Observation

Following the precedent of earler X-37B flights, it is unlikely that orbit data will be made available via Space-Track. Amateur visual observers would normally hope to get the chance to observe the spaceplane soon after launch and measure its orbit. Unfortunately, the situation for this launch will be similar to the previous flight with passes over the world's populated areas happening in daylight for the first week or so.

In order to be observed visually, a satellite needs to be in sunlight and the observer in darkness. This occurs in the region of the terminator, or line that separated the day and night zones of the Earth. The map shows that this occurs around 10° north latitude and 20° south.

The majority of satellite observers are based in Europe and the USA, far away from the two visibility zones. In fact, very few people live at the critcal latitudes that cover mainly central South America, central Africa and northern Australasia.

After a couple of weeks the orbit will have moved to where the X-37B will potentially be visible to lots of observers. However, by that time it will be difficult to find because there will be few, if any, clues as to its actual whereabouts and it will have changed orbit from it's initial one.

Eventually, it will be found.

Page Date: 2020 May 12
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