SpaceX will launch a Dragon cargo ship to the International Space Station for NASA today. Here's how to watch live.

Editor's note: SpaceX has successfully launched the Dragon CRS-21 cargo mission for NASA and landed its Falcon 9 rocket. Read our launch wrap story here.

CAPE CANAVERAL, Fla. — SpaceX will launch a Dragon spacecraft packed with NASA cargo to the International Space Station today in its first uncrewed mission with its upgraded spacecraft.

At 11:17 a.m. EDT (1617 GMT) today (Dec.6), a previously flown SpaceX Falcon 9 rocket will take to the skies here from NASA’s Kennedy Space Center. The two stage launcher will blast off from Pad 39 lofting a robotic Dragon cargo capsule carrying more than 6,400 lbs. (2,903 kilograms) of fresh supplies, experiment hardware and other gear for the astronauts aboard the orbiting lab. 

You can watch the launch live here and on the homepage, courtesy of NASA, beginning at 10:45 a.m. EST (1545 GMT). You can also watch directly via NASA TV or SpaceX.

Related: Tissue chips and organoids: The weird science on SpaceX's CRS-21
How SpaceX's Dragon Space Capsule Works (Infographic)   

Today's launch attempt comes 24 hours after SpaceX stood down from its original launch date of Dec.5. The slip was due to poor weather conditions at the recovery zone. SpaceX relies heavily on its fleet of used rocket boosters, so the company wanted to make sure that this rocket would be able to land on the drone ship safely and survive the trek back to port.

The weather outlook was iffy going into Saturday's attempt, with forecasters at the 45th Weather Squadron predicting a 50% chance of favorable conditions for liftoff. The primary concerns were thick clouds and cumulus clouds; however, rough seas at the landing zone proved to be too risky. So officials decided it was best to wait 24-hours for improved conditions. 

Today's attempt is the first of two potential backup attempts as the forecast improves to 70% favorable. There is another opportunity on Tuesday if the rocket can’t get off the ground today. If neither of those two chances works out, then the team will have to stand down for 10 days as the phasing with the space station is not ideal for docking. 

 Commercial cargo 

The flight is the first resupply mission under SpaceX’s second commercial resupply services contract with NASA and the first to use an upgraded Dragon cargo craft. The vessel is the same as its astronaut-toting counterpart, Crew Dragon, and can carry more cargo than its previous iteration. 

SpaceX is now one of three commercial partners that will be sending cargo to the space station. (Northrop Grumman and Sierra Nevada are the other two.) Under the first round of CRS contracts awarded in 2008, Northrop (then Orbital ATK) and SpaceX delivered more than 93,800 kilograms of cargo to the ISS over 31 missions for approximately $6 billion. 

With this second round of contracts, and three providers, NASA will order missions as needed and the total prices paid will depend on the type of mission ordered. The agency said that the maximum potential value of all contracts is $14 billion. 

Tucked inside the cargo craft is a bevy of research experiments and crew supplies that will support a host of science investigations that focuses on life sciences, regenerative medicine and much more. 

Bristol Myers Squibb is sending a payload that will look at protein crystallization in microgravity. To that end, the company is sending different types of immune system proteins, called monoclonal antibodies, into space. These types of proteins target cancer cells, and the researchers hope this investigation will help lead to improved drug therapies and manufacturing processes.  

The National Institutes of Health are sending three different payloads that focus on tissue chips in space. Tissue chips are small devices used to grow human cells in space to study the onset of disease. Because of the effects of microgravity, these types of experiments can help researchers better understand disease progression and can lead to the development of new treatments. 

One of these investigations will include tissue samples from Central Floridians. Thanks to a partnership between Advent Health and the University of Florida, skeletal muscle bundles affixed to tissue chips will be headed to the orbital outpost. 

These samples will help researchers to better understand how muscle atrophy in the absence of gravity. This research has both terrestrial and space-based implications. During their time on orbit, astronauts work out daily to help combat bone and muscle loss, just like older patients and patients with muscle wasting diseases do here on Earth. By better understanding the physical processes, researchers could manufacture improved therapies to help mitigate muscle loss. 

Related: SpaceX rocket launches for record 7th time, nails landing at sea

 Dueling Dragons 

This is the first time SpaceX is launching an upgraded version of its cargo craft. The gumdrop-shaped vessel will be launching from the same pad that four astronauts launched from last month. Once it arrives on station, it will mark the first time (but not the last) that two Dragon spacecraft will be attached to the orbital outpost. 

This version of Dragon is slightly different from its crew-toting counterpart as it lacks the important systems needed to keep humans safe: life support systems, an emergency escape system, and control panels to manually fly craft if need be. Instead this Dragon is a cosmic moving truck, sending supplies to the crew. 

Previously, Dragon cargo missions have launched from SpaceX's other pad, Space Launch Complex 40 just down the road at Cape Canaveral Air Force Station, but now all Dragons (Crew and Cargo) will be launching from the same pad: 39A. 

SpaceX leased this pad from NASA back in 2014, and thanks to infrastructure upgrades necessary to launch astronauts, this locale is now Dragon's main hub. Pad 39A features a futuristic-looking walkway known as the Crew access arm. While designed as a means for astronauts to board their spacecraft, the walkway serves another purpose — an access point for researchers to load sensitive equipment and payloads that cannot sit packed up in the craft for extended periods of time. (Like rodents or living cells.) 

These types of payloads are loaded hours before the rocket is set to blast off. The previous version of the Dragon required the rocket to be horizontal on the pad in order to load cargo, but now that's all changed. Now crews can load the Dragon while it's vertical, thanks to the trusty new access arm. 

"We are designed to go out of LC 39 A for these upgraded Cargo Dragon flights," Sarah Walker, director of Dragon mission management at SpaceX said during a prelaunch news briefing on Dec. 4. "That is a huge advantage to us."

"It allows us to be able to perform late load cargo while the vehicle is already vertical and allows us to do it even closer to T-zero," she added. "So yes, all Dragon missions will go out of LC 39A."

 Centennial Falcon  

Today's launch marks the 101st flight overall for SpaceX’s workhorse two-stage Falcon 9 rocket. The liftoff is expected to feature a veteran Falcon 9 first stage, designated B1058, that has three flights under its belt. This frequent flyer previously launched two NASA astronauts on a trip to the space station as well as a communications satellite for the South Korean military, and a batch of the company’s own Starlink satellites

Flying previously flown boosters has become commonplace for SpaceX, as the company continues to prove the Falcon 9's reliability. In fact, this mission marks the 24th flight of 2020 for SpaceX, with the majority of those missions having flown on veteran rockets rather than brand new ones. 

To date, SpaceX has successfully landed its first-stage boosters 67 times. Now that the company has two fully operational drone-ship landing platforms — "Of Course I Still Love You" and "Just Read the Instructions" — in Florida, it’s able to launch (and land) more rockets. The veteran, "Of Course I Still Love You," is already at the recovery zone waiting for its turn to catch B1058 when it returns to Earth this afternoon. 

Because this is a Dragon mission, the company's fairing catchers are not active, but a Dragon recovery vessel, GO Navigator is stationed out in the Atlantic along with the drone ship, waiting for today’s launch attempt. 

If all goes as planned, the Dragon will arrive on station and dock at the Harmony module’s space-facing port approximately 27 hours after it blasts off. 

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Amy Thompson
Contributing Writer

Amy Thompson is a Florida-based space and science journalist, who joined as a contributing writer in 2015. She's passionate about all things space and is a huge science and science-fiction geek. Star Wars is her favorite fandom, with that sassy little droid, R2D2 being her favorite. She studied science at the University of Florida, earning a degree in microbiology. Her work has also been published in Newsweek, VICE, Smithsonian, and many more. Now she chases rockets, writing about launches, commercial space, space station science, and everything in between.