No Rest for SpaceX as It Prepares for Thanksgiving Day Launch

SpaceX’s Falcon 9 v1.1 with the SES-8 satellite sitting on the launch pad Monday. Photo: SpaceX

The SpaceX launch team isn’t taking a break for Thanksgiving. The Falcon 9 v1.1 rocket was set to lift off on Monday from Cape Canaveral in Florida with the company’s first geostationary satellite payload, but a trifecta of hiccups forced an abort of the launch. And the Federal Aviation Administration says because of busy holiday air travel, they won’t allow another launch attempt until the skies are quiet on Thanksgiving day.

The 224 foot-tall Falcon 9 rocket sat ready on the launch pad, loaded with fuel and the liquid oxygen that serves as the propulsion source for the nine Merlin engines that power the first stage. But around 13 minutes before the scheduled launch, the first of three holds occurred after an issue related to a relief valve within the LOX system. A second hold was the result of a minor electrical issue.

After careful analysis, launch controllers were confident each of the first two issues had been resolved and the countdown continued. But the oxidizer relief valve problem appeared on their screens once again, so Monday’s launch was scrubbed.

“We observed unexpected readings with the first stage liquid oxygen system, so we decided to investigate,” was the short explanation provided by SpaceX in a statement.

Company founder and CEO Elon Musk added on Twitter the team saw “pressure fluctuations” in the first stage oxidizer tank, and they wanted to be “super careful” before proceeding.

Unfortunately, the FAA, which controls the airspace for rockets as well as airplanes, had already determined that launch opportunities on Tuesday and today might interfere with busy holiday airline schedules due to the airspace closure around Cape Canaveral during launch windows. So SpaceX announced the next opportunity to fly their rocket would be at 5:38 p.m. ET on Thanksgiving day. If the launch does occur tomorrow, it will be the first Thanksgiving launch from Cape Canaveral since 1959.

The payload is significant for SpaceX because it’s the first time the company will launch a satellite into geostationary orbit. Earlier Falcon 9 launches delivered payloads into low-earth orbit including the company’s Dragon spacecraft that has made three trips delivering cargo to the ISS, and a Canadian research satellite launched earlier this year.

The SES-8 satellite being prepared for its ride to geostationary orbit. Photo: SpaceX

During the satellite launch on September 30, SpaceX tested the Falcon 9′s second stage rocket by attempting a restart of the engine once payload had been delivered to the proper orbit. This was part of its development of a second stage that could deliver payloads to a geostationary orbit.

The reason for the extra boost is because geostationary satellites must travel much, much further before they are deployed. Unlike most satellites in low-earth orbit that circle around the earth and cover most of the non-polar regions of the planet over the course of several orbits, geostationary satellites live up to their name by staying fixed over a particular location. They’re able to do this thanks to an orbital period of 23 hours and 56 minutes (and 4 seconds), the same time it takes the earth to spin one time. In order to stay in a fixed location (most of them are communication or broadcast satellites) they must reside at much higher altitudes of 22,236 miles compared to around 200-300 miles for many low-earth orbiting satellites. The ISS is at roughly 250 miles with an orbital period of 93 minutes.

But to take advantage of some orbital mechanics, the satellite is actually boosted to a much higher, and very elliptical “transfer” orbit before onboard propulsion delivers it to its final circular orbit. So SpaceX will boost the satellite to more than 49,000 miles at the high point — or apogee — of its transfer orbit (80,000km x 295km).

In order to log the extra frequent flier miles, SpaceX’s second stage will make two burns separated by a long coasting phase. The first will last five minutes and 20 seconds and will be followed by an 18 minute coast. Then the second stage Merlin engine — which is optimized for operating in the vacuum of space — will be restarted with the second burn lasting just one minute.

The SES-8 satellite will park itself over south Asia, China and India and will provide communication and broadcast signals for the region. In an interesting twist, the satellite was built by Orbital Sciences, the Virginia based company that also is competing with SpaceX for payload contracts to the International Space Station. Orbital has been building satellites, as well as launch vehicles for decades.

SpaceX has one more launch on its docket for this year, scheduled for late December. Its third of 12 cargo missions to the ISS is planned for early 2014. After Orbital’s successful demonstration and docking to the ISS back on September 30, the company is planning its first contracted cargo delivery for next month.

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