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SpaceX Falcon 9 shutdown
A launch pad camera shows the Falcon 9 rocket’s engines flaring during a last-second shutdown. (Credit: SpaceX via YouTube)

A wayward boat and a load of liquid oxygen that got too warm forced SpaceX to abort what might have been a successful launch of the SES-9 telecommunication satellite today, just as the engines were firing up.

The snags mean SpaceX will have to wait until at least Tuesday for the next opportunity to launch its Falcon 9 rocket from Cape Canaveral Air Force Station in Florida, and to try landing the first-stage booster on an oceangoing platform in the Atlantic.

Today marked the third scrub for the launch, which is aimed at putting Luxembourg-based SES’ satellite into orbit to provide TV and data services to customers in the Asia-Pacific region. The first two delays were due to concerns over chilling down the rocket’s liquid oxygen propellant to the optimal temperature. Liquid oxygen played a role in today’s postponement as well, but there were a couple of additional twists.

The countdown was held up for more than a half-hour because an unauthorized vessel was in the “keep-out zone,” which is meant to keep boat traffic out of harm’s way as the rocket passes overhead. After a helicopter went out to shoo the ship out of the zone, SpaceX got clearance to launch at 7:21 p.m. ET (4:21 p.m. PT).

When the countdown clock reached zero, the engines flared up – and then immediately shut themselves down.

SpaceX’s billionaire founder, Elon Musk, said in a tweet that the shutdown was triggered by a low-thrust alarm about the engines. He said rising temperatures in the liquid oxygen tanks contributed to the weak thrust, and suggested that the launch might have gone ahead if it weren’t for the earlier countdown hold.

SpaceX launch commentator John Insprucker said the Falcon 9 rocket and the satellite were safe. “This is a sequence that we’ve gone through … many times,” Insprucker said during a countdown webcast.

The U.S. Air Force 45th Space Wing, which handles range issues at Cape Canaveral, said on Facebook that the launch was officially scrubbed at 7:34 p.m. ET, and that the next launch opportunity would come up in no less than 48 hours.

Putting the SES-9 satellite into its proper orbit is the mission’s primary objective. After the Falcon 9’s second stage separates to continue the ascent, SpaceX wants to try bringing the first stage down to what it calls an “autonomous spaceport drone ship” hundreds of miles out in the Atlantic Ocean. The company has come close to making a successful at-sea rocket landing three times over the past 13 months or so – in January and April of 2015 as well as last month.

SpaceX brought a Falcon 9 booster back to its Cape Canaveral landing zone after a launch last December, safe and sound, but the company wants to perfect the at-sea landing routine for situations in which an on-land touchdown is not logistically possible.

Because of the higher-than-usual propellant requirements for the SES satellite launch, SpaceX doesn’t think the landing will be successful this time – but it wants to try anyway. Rocket recovery and reuse are key steps in Musk’s plan to reduce the cost of access to space and eventually make it possible to send colonists to Mars.


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