December 13, 2017

Astro-event: SDO and STS-130 are go!

Two (count ‘em!) launches will light up the Florida Space Coast over the next few days; that of the Space Shuttle Endeavour on mission STS-130 and the Solar Dynamics Observatory (SDO). STS-130 is scheduled to liftoff from launch pad 39A out of the Kennedy Space Center on the morning of Sunday, February 7th at 04:39 AM EST enroute to the International Space Station. Cargo includes the Tranquility connecting node which houses the Cupola, a Millennium Falcon-like window that will give residents unprecedented views and aid in spacewalks and exterior work.

This will be the second to last flight of Endeavour, the final night launch, and the fifth to last of the shuttle program.   Conditions willing, Astroguyz intends to make an off-site pilgrimage to the launch, as part of our “All STS-130, all-the time,” campaign culminating with the NASA tweetup at the Johnson Space Flight center on February 17th!

Two days later, NASA’s Solar Dynamics Observatory (SDO) is to launch out of neighboring Cape Canaveral Air Force Station on Tuesday, February 9th. The hour-long launch window opens at 10:30 EST local, and SDO is part of NASA’s Living With a Star (LWS) program. SDO is headed for an inclined geosynchronous orbit over the US East Coast longitude to provide nearly continuous monitoring of the Sun. SDO with also provide a continuity replacement for ESA’s SOHO, which has provided some outstanding science over its +10 year career. SDO is also hosting its own tweetups, as well!

So, you ask, how might I, the satellite spotting public, spot these celestial sights? Well, SDO will be headed out in a south easterly direction, (link) and its mission beyond Low Earth orbit will take it well out of visible sight. Centaur main engine start, burn, cut off all occur over the Pacific to the southeast of Guam, and may provide some outstanding night time views of the event. The action starts 1:42 after launch.   As for STS-130, views of the actual launch up the eastern seaboard should be a good show; unfortunately, once in orbit, geometry will favor Europe and Northern Asia for the pre-dawn passes and Australia-south Pacific on the dusk passes.

The astro-word for this week is geosynchronous orbit. Place a satellite at a distance of 22,236 miles above the Earth’s surface, and it will orbit once every 24 hours, and thus stay in a fixed position above its respective longitude as seen from the Earth. SDO is headed for just such an orbit; this will enable it to observe the Sun and downlink to the Goddard Spaceflight Center in Beltsville, Maryland nearly without interruption. First proposed by famed science fiction writer Arthur C. Clarke in 1945, geosynchronous orbit is sometimes also referred to as the Clarke Belt in his honor. The first satellite to reach geosynchronous orbit was Syncom 2 in 1963, and the population of the Clarke Belt is estimated to be in excess of 300. It’s tougher to put satellites out in a geosynchronous orbit, and once there, they are well beyond the range of shuttle retrieval and repair, as the orbiters operate exclusively in Low Earth Orbit. One plus is that three satellites placed in orbits 120° apart can provide global coverage for communications purposes. These satellites are too distant to be spotted with the naked eye; they can, however, on occasion be seen via a wide field telescope as they slowly nod north-to-south-to-north in their lazy orbits!

Comments

  1. John M says:

    “… geosynchronous orbit is sometimes also referred to as the Clarke Belt…”

    Well, you’re close. A geosynchronous orbit can be called a Clarke Orbit. Objects in Clarke Orbits are within the Clarke Belt.

    Expressed the other way around, the Clarke Belt is the region of space populated by objects in Clarke Orbits.

  2. David Dickinson says:

    Point taken; a more exact way to say it would be “the area of geosynchronous (or geostationary) orbit is also referred to as the Clarke Belt…” Thanks for the clarification.

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  3. [...] orbit:  Place a GEO satellite in orbit with a zero degree orbit, and it is considered Geostationary. Also sometimes referred to [...]

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