Building on more than a decade of data from International Space Station (ISS) research, NASA is expanding its materials science research by flying an experiment on the U.S. Air Force X-37B space plane.
By flying the Materials Exposure and Technology Innovation in Space (METIS) investigation on the X-37B, materials scientists have the opportunity to expose almost 100 different materials samples to the space environment for more than 200 days. METIS is building on data acquired during the Materials on International Space Station Experiment (MISSE), which flew more than 4,000 samples in space from 2001 to 2013.
“By exposing materials to space and returning the samples to Earth, we gain valuable data about how the materials hold up in the environment in which they will have to operate,” said Miria Finckenor, the co-investigator on the MISSE experiment and principal investigator for METIS at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “Spacecraft designers can use this information to choose the best material for specific applications, such as thermal protection or antennas or any other space hardware.”
We’re curious about something not mentioned in the release. How different is the orbit of the X-37B from the ISS, in terms of both altitude and inclination, and what effects might that have on the exposed materials?
Next up, Space-X. We’ve all enjoyed watching Elon Musk’s Falcon 9 attempt to safely land after orbital launch missions. Looks like they’ll try again in June. But the other major endeavor underway at Space-X is to crew certify a manned spacecraft. And one of the key tests for that is the pad abort. We’ve all seen the escape tower atop Mercury and Apollo capsules. Space-X uses a rather different approach with their manned variant of the Dragon spacecraft.
By happenstance, we were up late last night, and happened to click on the live feed of the Space-X Falcon 9 launch live feed at almost exactly T-1 minute. The launch was nominal, and I watched all the way to solar panel deployment. In about two days, the Dragon capsule will rendezvous with the International Space Station, and deliver its cargo. So far, so good.
The radical part of the Falcon 9 program is the attempt to recover the first stage of the rocket. Rather than simply falling away as most rockets do, the Falcon 9 is intended to make a maneuver to a reentry to a planned point, use its motor to slow down, deploy landing legs, and land on a barge. Recovering the stage means the expensive part of the launch, the actual rocket motors, can be reused, greatly decreasing the cost of launching a pound of payload to orbit.
Space-X had tried the maneuver portion of the reentry on previous launches. This morning was the first attempt to actually land the rocket. An unmanned barge serving as a landing platform was deployed off the Atlantic coast. Unfortunately, the rocket landed hard per Space-X head honcho Elon Musk, and recovery failed.
Rocket made it to drone spaceport ship, but landed hard. Close, but no cigar this time. Bodes well for the future tho.
Spaceflight is hideously expensive, roughly $10,000 per pound to Low Earth Orbit. And a large part of that is because the rockets that boost payloads into orbit are expended. Every rocket motor is an incredibly precise, extremely complicated engineering marvel. And yet, they’ve traditionally been used once, and thrown away.
Probably something like 90% of the fuel and thrust of a rocket sending a payload to orbit is spent sending the fuel and rocket up, not the payload itself. As any airline pilot can tell you, it takes fuel to haul fuel. That’s why most rockets are multistage. After burning the first stage, it’s just dead weight, and no sense hauling it any further. A lighter second stage with a smaller motor can take over.
But it is those very same first stage engines that are most expensive.
So Space-X looked at ways to recover those very expensive engines. And decided the best way to save them was to have the first stage make a controlled descent to the earth, eventually with the rocket landing on deployed landing legs. If that seems pretty incredible to you, well, you’re not alone. When I first heard of the plan, I was skeptical. It’s a difficult flight to control, and the extra weight of fuel needed imposes its own penalty.
But then, unlike my co-author Roamy, I’m not a rocket scientist.
Space-X first decided to see if they could actually control a rocket in low altitude and have it successfully land on its own feet, as it were. To do so, they built a low altitude rocket resembling the Falcon 9 first stage and called it the Grasshopper.
As for controlling the first stage after an actual launch, I forgot they would be letting the atmosphere do a lot of the work. When a rocket first takes off, it’s at its greatest weight, and in the thickest air, and so has the least acceleration. As the weight of fuel burns off, and the air resistance diminishes at altitude, and yet the thrust generated remains the same, the acceleration increases, reaching its maximum at burnout, or “staging” if you will.
So now our first stage, at something like 50 miles altitude, effectively the edge of space, is flying separate from the second stage and the payload. Rather than just tumbling down, it can use only one of its 9 motors to begin a controlled deceleration. And as it encounters ever thickening atmosphere, its speed will decrease at an ever increasing rate. The rocket itself is pretty light. A vast percentage of its takeoff weight is its fuel (and oxidizer, of course). With most of it gone, it takes less thrust (and consequently, even less fuel) to decelerate.
Friday’s launch was a test primarily of the ability of Falcon 9 to handle the high altitude part of a reusable booster, that is, the part from Mach 10 down to low airspeeds. And it was intended to drop the booster in the ocean. If things had gone wrong, slamming a rocket into the roof of granny’s house would be bad. Because it landed in a salt water environment, rebuilding the liquid fuel motors would be quite difficult. In the future Space-X hopes to land first stages on dry land. If they can successfully do so (and it is really starting to look like they can) and they can quickly refurbish the booster for a second flight, they may cut costs of launch, in terms of pounds to LEO in half. That would the most significant decrease in launch costs in the history of spaceflight.