A Falcon 9 rocket blasts off for the ISS on 18 April (Image: NASA TV)

Dragon has once again spread its wings. Today commercial spaceflight firm SpaceX successfully launched its third cargo mission to the International Space Station (ISS), sending a Dragon capsule loaded with just over 2 tonnes of supplies and science experiments.

The capsule lifted off aboard a Falcon 9 rocket from Cape Canaveral in Florida at 3.25 pm local time. It is slated to dock with the ISS on Sunday and deliver the equipment and experiments, including a set of robotic legs, a collapsible garden and microbes brushed off a Tyrannosaurus rex fossil.

Following the launch, part of the rocket was also supposed to fire engines as it fell back to Earth and deploy a set of experimental landing legs, which could one day enable rockets to be reused. The rocket should have attempted a mock landing over the Atlantic Ocean, but weather may have complicated the effort.


Sea legs

“The rocket flight on the way up was perfect, as far as we could tell,” SpaceX founder Elon Musk said during a press briefing. But the seas were very rough in the Atlantic, with reports of high waves, and Musk thinks this could have affected the landing. “It was very heavy seas, so I wouldn’t give high odds that the rocket was able to splash down successfully.”

Currently, the rockets that send cargo and crew to the ISS are discarded. A rocket that can return to Earth and safely touch down for reuse could lower the cost of spacecraft by a factor of 100, according to Musk. A version of the system could also bring astronauts back from Mars.

A member of SpaceX’s launch team reports that the rocket reignited its engines after it separated from the spacecraft, stabilising it and slowing it enough to survive re-entering Earth’s atmosphere. The team was recording video of the rocket as it came down over the ocean and should know soon whether the landing legs deployed.

No matter what happened, the experiment shows that having landing legs on the rocket didn’t affect its flight. “We were able to show on ascent that the legs don’t have a negative impact on the rocket,” says Musk. “Even though we probably won’t get the stage back, we’re starting to connect the dots about what’s needed.”

Astronaut garden

And even if the test landing went badly, a robot on the ISS will still get its own boost. Among the supplies and experiments aboard Dragon is a pair of legs for the humanoid robot Robonaut 2, which has been lending a hand to astronauts since the final space shuttle mission in 2011. Until those legs arrive, it will just be a torso.

When it docks to the ISS, Dragon will also deliver the Vegetable Production System, or Veggie, a plant growth chamber that will test how well red romaine lettuce seedlings sprout in space.

The chamber collapses for easy storage during flight and extends to create a “garden” that is about 29 centimetres wide by 37 centimetres deep – the largest plant chamber in space to date. The hope is that such chambers could be used to grow food on longer deep-space missions, or to provide astronauts with some recreational gardening.

Dragon’s science haul also includes microbe samples from Project MERCCURI, which asked people to collect and identify microbes in public spaces such as sports stadiums and museums. Cultures will be grown on Earth and on the ISS to compare how low gravity influences the organisms.

The 48 samples selected to head to the ISS include microbes found on “Sue” the T. rex at the Field Museum in Chicago and on John Glenn’s Mercury space capsule, Friendship 7, at the Smithsonian’s National Air and Space Museum in Washington, DC.