With latest ISS docking, SpaceX settles into its supply ship role

Now on its 10th re-supply mission, the private space company has become an essential part of the supply lines supporting an increasingly intricate space operation.

First Look

It’s not quite Amazon Prime, but four days isn’t too bad for a shipment into space.

After a delayed launch and one aborted delivery attempt, SpaceX’s caution paid off Thursday when its Dragon capsule stuffed full of food, equipment, and experiments successfully docked with the International Space Station (ISS).

Now on its 10th re-supply mission, the private space company has become an essential part of the supply lines supporting an increasingly intricate space operation.

After a GPS error scuttled its first docking attempt Wednesday, the Dragon capsule smoothly slipped close enough to the ISS for the space station’s robotic arm to snag the craft early Thursday morning, along with the 5,500 pounds of goodies on board.

“Looks like we’ve got a great capture,” radioed space station commander Shane Kimbrough.

In addition to a much needed food refresh, the capsule also contains more than 250 science experiments. NASA’s Lightning Imaging Sensor will record lightning strikes, which happen dozens of times per second somewhere on the planet. A crew of 40 mice will help scientists understand bone loss and the SAGE 3 ozone monitor will check in on the recovery of the planet’s ozone layer.  

“Dragon has now officially arrived at ISS,” European Space Agency astronaut Thomas Pesquet, who docked the capsule, said. “We’re very happy, indeed, to have it on-board and very much looking forward to the goodies, and the tons of science of cargo it carries.”

And there’ll be no shortage of stuff to unpack because a second shipment was hot on SpaceX’s tail. Russia’s Progress-66 cargo mission, with its nearly three tons of food, clothing, fuel, and other supplies, docked with the ISS less than 24 hours later.

As of Friday, the Dragon and Progress-66 capsules bring the current count of spacecraft docked with the ISS to four, according to NASA. The station’s slow and modular construction over nearly two decades may obscure the fact that it has matured significantly, becoming a bustling spaceport.

Continually staffed by an international crew of six astronauts orbiting the earth 15 times a day, the station has provided a space environment that boasts more than 16 years of habitation.

Those astronauts need water (about 3 gallons a day), oxygen, and food (almost 2 pounds per day) at the bare minimum, and even though water recycling and cabbage growing programs exist, the station is far from self-sufficient.

Those pounds don’t come cheap. While modern launches contracted to privately held Orbital Sciences and SpaceX cost far less than the space shuttle did, their relatively modest capacities actually mean that the cost of shipping to space is on the rise, up to $30,000 to $40,000 per pound from $10,000, according to Business Insider calculations.

To keep the operation functioning smoothly, the ISS relies on support from a number of organizations, including Russia’s Roscosmos agency and Japan’s JAXA in addition to Orbital Sciences and SpaceX. These collaborations build in redundancy, so that even if one shipment doesn’t make it another isn’t far behind.

The result is a carefully choreographed dance of spacecraft constantly passing between Earth and the ISS. NASA lists almost a dozen operations in the past three months alone, including launches, captures, dockings, and releases.

Now that all the work on the ground has paid off with a successful capture, it's time for the astronauts to leap into action. They have 30 days to unload the cargo, carry out initial experiments, and reload it with waste and samples before it undocks and departs for a splashdown in the Pacific Ocean.

“Great job with Dragon capture, and sorry about the delays,” said astronaut Mike Hopkins from mission control in Houston as the capture was completed. “Now the real work starts.”

Back on Earth, Orbital Sciences is preparing its Cygnus spacecraft for the next resupply mission, now less than a month away.