Having originally been scheduled to celebrate Thanksgiving by taking to the stratosphere, SpaceX's launch was aborted at the last moment today. The Falcon 9 rocket had been scheduled to take off from Florida's Cape Canaveral Air Force Station sometime during a 65-minute launch window starting at 5:39 PM ET.

The aborted launch was initially set to occur earlier this week, but SpaceX missed its last launch window due to a technical glitch. "Saw pressure fluctuations on Falcon boost stage liquid oxygen tank," SpaceX CEO and founder Elon Musk wrote on Twitter at the time. "Want to be super careful, so pushing launch to Thurs."

A significant milestone for SpaceX

Had today's launch gone smoothly, it could've been a significant milestone both for SpaceX and for the commercial space transportation industry more broadly. Instead, engineers will need to figure out what went wrong before scheduling another launch. Fortunately for both SpaceX and the company's client, the payload doesn't appear to have been damaged.

SpaceX's Falcon 9 would have blasted the SES-8 communications satellite — owned by Luxembourg-based SES World Skies — into geostationary orbit. It's the first time SpaceX has launched a commercial communications satellite, and will set the stage for the company to perform subsequent launches that currently take place overseas. "This launch is obviously very important to the future of SpaceX," Musk told reporters on Sunday. "We're very appreciative that SES would place a bet on SpaceX here."

So far, the upgraded Falcon 9 (known as version 1.1 of the rocket) hasn't boasted a stellar track record. The 224-foot-tall rocket was initially tested with the launch of a Canadian weather satellite earlier this year. The Falcon 9 completed its mission, but not without failing at a key maneuver that'll be necessary for the SES-8 mission. But even as SpaceX attempts to break into the commercial satellite business, they're already keeping busy with government projects: the company has a $1.6 billion NASA contract to complete 12 cargo resupply flights.

Update: As engines were starting and the launch timer was counting down to zero, the Falcon 9 aborted liftoff and shut down its engines. Engineers haven't yet said why — it's quite likely they don't know — but the live feed's announcers say that they're poring through data retrieved from the rocket.

Update 2: SpaceX says the rocket is "safe" and that its flight computer automatically shut down the launch with about a second to go. Because it has a 65-minute launch window, engineers are looking at whether they can simply refuel and try again — otherwise they'll have another launch window available tomorrow around the same time of day. Elon Musk has tweeted that everything "Seems ok on closer inspection."

Launch aborted by autosequence due to slower than expected thrust ramp. Seems ok on closer inspection. Cycling countdown. — Elon Musk (@elonmusk) November 28, 2013

Update 3: As of 6:22pm ET, the countdown appears to be back on, with the rocket ready to launch about 20 minutes from now.

Update 4: The latest launch attempt was aborted just 4 seconds prior to liftoff. Elon Musk tweeted a few minutes prior that it would "probably [be] a few days before next attempt" if this most recent launch was aborted. Indeed, hosts on the SpaceX livestream have confirmed that they are taking "the safe path," with no further plans to launch today. The rocket will be de-tanked and return to horizontal position, with another launch attempt taking place within a few days.

Elon Musk confirmed on twitter that they called manual abort, saying it was "better to be paranoid and wrong."