Live mice, cabbage, and a drone ship: Your SpaceX Dragon launch preview

SpaceX is ready to launch its Dragon cargo spacecraft for the first time since a catastrophic accident last June. Tomorrow afternoon, a Falcon 9 rocket is scheduled to blast off from Cape Canaveral, Florida, carrying live mice, cabbage and an expandable habitat module to the International Space Station. The private spaceflight company will also try again to land the spent first stage of its rocket on a drone ship in the Atlantic Ocean.

Watch: SpaceX CRS-8 launch

Launch: Friday, April 8, 4:43 p.m. EDT (20:43 UTC)
Instantaneous launch window

NASA TV coverage starts 3:00 p.m.
Backup launch opportunity Saturday, April 9, 4:20 p.m.

Berthing: Sunday, April 10
NASA TV coverage begins 5:30 a.m. EDT
Dragon installation approximately 9:30 a.m.

Return to Earth: May 11

Once in orbit, Dragon will spend two days traveling to the ISS, arriving early Sunday morning. Astronauts Jeff Williams and Tim Peake will snag the vehicle with the station's robotic arm, allowing flight controllers in Mission Control Houston to install the spacecraft on the Earth-facing side of the station’s Harmony module.

Dragon's arrival will mark the end of an extraordinarily busy stretch of crew and cargo traffic at the orbital laboratory. "This will bring to the close a very busy season of visiting vehicles," said Kirk Shireman, manager of the ISS program, speaking to reporters today from Kennedy Space Center. "When Dragon arrives on Sunday morning, it will close a period of four visiting vehicles in four consecutive weeks," he said. Preceding Dragon was the Expedition 47 Soyuz crew, followed by Cygnus and Progress cargo ships.

Dragon will become neighbors with Cygnus, which was installed on the Harmony module's nadir port March 26. The Dragon-Cygnus combo heralds the first time two U.S. cargo vehicles have been attached to the ISS at the same time. Dragon will also help tie the record for the total number of vehicles—six, counting in the two crew-carrying Soyuz spacecraft—attached to the station at once. That number was last reached back in 2011.

Dragon's total cargo haul is 3.1 metric tons. Of that, 1.7 tons are pressurized. NASA breaks this down as:  

• Science investigations: 640 kg
• Crew supplies: 547 kg
• Vehicle hardware: 306 kg
• Computer resources: 108 kg
• Russian hardware: 33 kg
• Spacewalk equipment: 12 kg

Nestled inside Dragon's unpressurized trunk—the cylindrical part of the spacecraft beneath the main capsule—is BEAM, the Bigelow Expandable Activity Module. BEAM, which will be unpacked by robotic arm in mid-April and installed on the station's Tranquility module, is a two-year experiment to test out human-occupied inflatable space habitats.

You can read our in-depth look at BEAM here.

Last week, ISS chief scientist Julie Robinson told reporters more than 250 science investigations will take place during Expeditions 47 and 48. Here are a few highlights coming aboard with Dragon:

• Last year, astronauts snacked on the first-ever crop of space lettuce as part of NASA’s pick-and-eat salad initiative. The agency is shipping 18 new "plant pillows" of chinese cabbage and romaine lettuce. Food tasters at the Johnson Space Center in Houston, Texas rated the cabbage as the tastiest menu option. "We are also working on sending some ranch dressing up," said principal investigator Gioia Massa.
  
  
• A team led by scientists at the University of Southern California is shipping up a batch of fungi to take part in an experiment that could help keep drugs from expiring during long trips to Mars. "We are excited to be the first team on Earth to launch fungi into space, for the purpose of potentially developing new medicine for use on both Earth and space," said principal investigator Clay Wang.
   
• A Jet Propulsion Laboratory-headed group will continue tracking and monitoring the space station's sealed microbial environment. Experiment goals include looking at possible countermeasures against harmful bacteria, and conversely investigating possible uses for helpful bacteria.
   
• Pharmaceutical giant Eli Lilly is sending 20 live mice to the station as part of a muscoskeletal experiment that could give scientists insight into muscle wasting diseases. Crewmembers will get a chance to handle the mice, but unfortunately for the rodents, the experiment is "terminal." Said an Eli Lilly representative: "Unfortunately, there is no way yet to bring mice live back to Earth."
   
• Anna-Sophia Boguraev, a high school senior from Bedford, New York, was the winner of a Boeing-sponsored competition to fly a student genetics experiment in space. "One of the things that spaceflight—especially, long-term spaceflight—does, is severely weaken the immune system," Boguraev said. Her experiment will try out a DNA replication technique that could be used to study astronauts' genetic changes during spaceflight.

As has been common during recent SpaceX flights, much of the hype surrounding the launch itself will focus on an attempt to recover the Falcon 9's first stage booster. In December, SpaceX flew a spent rocket stage all the way back to Cape Canaveral for an upright landing. But thus far, the company has yet to stick a landing on one if its autonomous drone ships, which have tried to catch rockets in both the Atlantic and Pacific oceans.

For high-energy boosts to geostationary transfer orbit, the Falcon 9 first stage is traveling too far and fast to fly all the way back to land, which makes a drone ship recovery the only option. For tomorrow's trip to low-Earth orbit, a land return might have been possible, but SpaceX is determined to perfect the drone ship technique. 

"The next two or three flights are going to be drone ship landings—there's no choice there, because we can't get to land," said Hans Koenigsmann, SpaceX's vice president of flight reliability. "So it's a good opportunity for us to refine our drone ship landing capabilities and get this done, because in the long run it's certainly something that we need to demonstrate over and over again to get the first stage back."