SpaceX

The Falcon 9’s two stages have moved to internal power, meaning they are running on their batteries through launch and ascent.

T-6 minutes and counting . . . The nine engines of the first stage are being conditioned to the frigid conditions they will encounter when super-cold liquid oxygen begins running through them at launch.

This fourth cargo mission by SpaceX will carry the first living creatures: a cadre of mice that will be used in microgravity research on bone density. The mice, part of a collaborative experiment including NASA and the Center for the Advancement of Science in Space (CASIS), will fly to space in their own habitat that will be transferred to the inside of the space station. A company called TechShot developed a Bone Densitometer that will be used to X-ray the mice. The official name of the payload is Rodent Research-1 and you can read more about it here.

The countdown is in its last, or terminal, phase and the launch team is moving through its steps methodically. Less than 10 minutes until liftoff at 1:52 a.m. EDT.

The final readiness poll has been conducted and the SpaceX CRS-4 mission is go. Controllers can still hold the count at any point before liftoff should an issue pop up.

The propellant tanks of the Falcon 9 are made from aluminum-lithium alloy while the top and bottom domes of the tanks are aluminum. SpaceX named its rocket after the Millennium Falcon from Star Wars. For the true devotees out there, this Falcon 9, called v 1.1., is an upgraded version of the original. It has the stronger Merlin 1D engines and other updates to the first design.

This morning’s SpaceX launch will be coordinated through the company’s launch control center here in Florida and the SpaceX mission control at the company’s headquarters in Hawthorne, California. NASA’s Mission Control in Houston is also taking part in this morning’s countdown since the Dragon spacecraft is delivering 2.5 tons of supplies to the International Space Station.

The Dragon spacecraft is running on its batteries now. Once it reaches orbit, the spacecraft will deploy a pair of solar array “wings” that will recharge the batteries.

We are at T-30 minutes and counting. The SpaceX launch team has not noted any technical issues. The weather is green across the board. Liftoff remains on track for 1:52 a.m. EDT

The Jet Propulsion Lab in Pasadena, California, developed one of the signature experiments for the station, the ISS-RapidScat. The device is flying inside the trunk section of the Dragon and will be connected to the outside of the station’s Columbus module which will give it an unobstructed view of the Earth more than 200 miles below. From there it will study the ocean winds on Earth and track hurricanes and storms. You can read about ISS-RapidScat in depth here and find out five important things about it here.