Friday, June 29, 2018

EM-1 Update: One of the Space Launch System's Secondary Payloads Spreads Its Wings for the First Time...

The NEA Scout spacecraft spreads its solar sail during a test at the NeXolve facility in Huntsville, Alabama...on June 28, 2018.
NASA / Emmett Given

NASA Tests Solar Sail for CubeSat that Will Study Near-Earth Asteroids (News Release)

NASA's Near-Earth Asteroid Scout, a small satellite designed to study asteroids close to Earth, performed a successful deployment test June 28 of the solar sail that will launch on Exploration Mission-1 (EM-1). The test was performed in an indoor clean room at the NeXolve facility in Huntsville, Alabama.

NEA Scout is a six-unit CubeSat that relies on an innovative solar sail for propulsion. It is one of 13 secondary science payloads NASA selected to fly on EM-1. The first in a series of increasingly complex missions, EM-1 will be the first integrated test of NASA’s Space Launch System rocket, NASA’s Orion spacecraft and the newly upgraded Exploration Ground Systems at Kennedy Space Center in Florida. In addition to testing these integrated systems, this first flight will also provide the rare opportunity for these small experiments to reach deep space destinations, conducting science missions and testing key technologies beyond low-Earth orbit.

“Developing a sail to harness the Sun’s energy to fly through space was once thought impossible,” said Joe Matus, NEA Scout project manager at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “Just in this decade we’ve seen innovation and progress on this promising technology and NEA Scout is another step to using solar sails to explore our solar system. This team has worked really hard to make this technology a reality, and knowing that the sail we just tested will be the actual sail that propels NEA Scout through space is very exciting, and a testament to the knowledge and capabilities of our team.”

NEA Scout will deploy from the rocket after the Orion spacecraft is separated from the upper stage. When deployed, the sail, which is square in shape, with each side about the length of a school bus, will harness the light of the Sun to use as propulsion to move through space. Instead of wind, solar sails reflect sunlight for thrust, minimizing the need for fuel. This method reduces the size and weight of the spacecraft, thereby resulting in cost savings. The NEA Scout solar sail will deploy from the spacecraft using four arms -- called booms -- to hold the sail, much like a sail on a ship. After deployment, the satellite will travel to and fly-by an asteroid, taking photographic data that will help scientists better understand not only the asteroid itself, but the risks and challenges that future human exploration missions may encounter.

“Over the last couple of tests of our engineering test unit, we made improvements to the spacecraft’s sail deployment system,” said Tiffany Lockett, NEA Scout project system engineer at Marshall. “This test is the first and only time the sail will be deployed before it flies on EM-1, so we had to make sure the system will work correctly. We are analyzing the test data to make sure the deployment system worked as expected, before final assembly into the spacecraft and delivery for launch.”

Solar sails can’t run out of fuel as long as the Sun shines, allowing them to propel spacecraft farther and faster than some traditional propulsion technologies. Spacecraft like NEA Scout are the next step towards larger and more capable solar sails that can take our science instruments farther into the solar system, enabling new science and exploration missions.

NASA’s Advanced Exploration Systems manages NEA Scout with the team led at Marshall with support from NASA's Jet Propulsion Laboratory in Pasadena, California and NASA's Langley Research Center in Hampton, Virginia. AES infuses new technologies developed by NASA's Space Technology Mission Directorate and partners with the Science Mission Directorate to address the unknowns and mitigate risks for crews and systems during future human exploration missions.

Source: NASA.Gov


Wednesday, June 20, 2018

SLS Update: Progress Continues to be Made on Prepping the Launch Vehicle Stage Adapter for Exploration Mission 1...

Foam is applied to the Launch Vehicle Stage Adapter that will fly on the Space Launch System's first flight, Exploration Mission 1, in 2020.
NASA / Tyler Martin

Foam and Cork Insulation Protects Deep Space Rocket from Fire and Ice (News Release)

Extreme temperatures -- ranging from minus 423 degrees Fahrenheit to more than 200 degrees Fahrenheit -- call for novel thermal protection systems on NASA's new heavy-lift rocket, the Space Launch System (SLS). NASA is advancing state-of-the-art technology for thermal protection with more environmentally friendly materials and 3D printed molds for smaller parts. With the power and precision needed for sending humans to deep space, SLS will launch astronauts in NASA's Orion spacecraft to distant destinations such as the Moon and Mars.

Spray-on foam insulation, along with other traditional insulation materials such as cork, will provide thermal protection for every rocket part, large and small. The insulation is flexible enough to move with the rocket but rigid enough to take the aerodynamic pressures as SLS accelerates from 0 to 17,400 miles per hour and soars to more than 100 miles above Earth in just 8 minutes. The cryogenic fuel, made up of liquid hydrogen and liquid oxygen, that powers the rocket has to stay extremely cold to remain liquid. Hydrogen has to remain at minus 423 degrees Fahrenheit and oxygen at minus 298 degrees Fahrenheit. If temperatures rise too high, the fuel would become a gas.

"As the Space Launch System flies, it builds up tremendous heat. Without insulation, heat from launch would affect the stability of the cryogenic propellants and the rocket’s structural integrity would be compromised," said Michael Alldredge, who leads the thermal protection system team for the SLS core stage at NASA's Marshall Space Flight Center in Huntsville, Alabama. “NASA is asking this unique foam material to do the incredible job of protecting critical rocket systems, which vary from large structures to electronics and fuel lines, in an unforgiving launch environment with extreme temperatures and pressures.”

Materials engineers qualified the third-generation, orange-colored spray-on foam insulation to meet the harsh environments that the SLS will experience. At the same time, they made the foam more environmentally friendly. The foam insulation is composed of two liquids -- isocyanate and a special polyol blend -- that stay separate in the pumping system and mix in the spray gun before releasing and rising into foam -- similar to hair mousse. When the foam is applied, it gives the rocket a light-yellow color that the Sun's ultraviolet rays eventually "tan," giving the SLS core stage its signature orange color.

Spray the Big Stuff

Foam will protect the larger of the hardware, including the entire SLS core stage that is the 212-foot-tall backbone of the rocket. The foam is applied with robotic or hand-held spray guns, and, much like painting walls in a home, hardware has to be primed and taped off before spraying begins. Primer serves as corrosion protection from the environment and enhances the bond between the insulation and the rocket.

Engineers will use a robotic system to apply both primer and foam to the cryotanks at NASA’s Michoud Assembly Facility in New Orleans where the core stage is being built. Manually-sprayed foam will cover the domes, or bottoms, of both cryotanks. The largest piece of SLS hardware built at Marshall, the launch vehicle stage adapter, which serves as a connector between the core stage and the interim cryogenic propulsion stage will have manually-sprayed foam.

The original plan was to use cork for the SLS launch vehicle stage adapter, according to Amy Buck, Marshall's launch vehicle stage adapter thermal protection systems lead, but the team determined that foam would be more efficient. "The foam is lighter," she said. "And since we have the resources to spray it by hand at Marshall, we are saving time and money because we don’t have to ship it to Michoud. We spray on the foam at Marshall at the same time the core stage pieces for the first SLS mission get their foam applied at Michoud."

"It takes about three months for the entire foam application process," Buck explained. “The prep work takes longer than the actual spraying. The hand-spraying only takes about 30 minutes for each 4-foot-wide section."

3-D Printed Molds Help Protect Smaller Stuff

Insulation protects many small parts of the rocket that play big roles. The avionics, the "brains" of the rocket, are located throughout the vehicle. Other small parts like the intertank's exterior pockets, the engine section's internal ducts and close-out areas of hardware -- where two major pieces connect -- require manually-sprayed foam or foam cast with 3-D printed molds.

“NASA is using a novel 3-D printing process to make customized molds for certain parts,” said Alldredge. “Some parts have unique geometries or are in locations in the rocket where it is difficult to cover them with spray foam. The 3-D printed molds allow us to shape insulation to protect specific parts.”

Small hardware like internal fuel systems and brackets on the feedline that run along the outside of the core stage and connect it to the engine section need pour foam. The foam is mixed and poured into a mold before it expands to fill the shape it enters.

Put Some Cork on It

Cork is heavier than foam but provides even stronger protection for certain applications. Cork comes in sheets and is applied to areas that have high predicted heat loads, like the core stage engine section, which houses four RS-25 engines that produce 2 million pounds of thrust. Cork is applied under the solid rocket boosters that provide 75 percent of thrust at liftoff and on the fairings, the areas where feedlines come out of the intertank and run down the rocket to connect the intertank to the other hardware.

After thermal protection material density and adhesion are verified for both foam and cork, engineers take thickness measurements to ensure the required amount of thermal protection has been applied. Overall thermal protection systems thickness for SLS ranges from about a half-inch to 2 inches. The launch vehicle stage adapter requires 0.7 inches of foam while the hydrogen tank requires around 1.2 inches because of its extremely cold temperature. The final system level test of the insulation, prior to flight, will be when the entire core stage will be tested with all four RS-25 engines firing, and the foam and cork guarding the hardware as hot and cold collide.

Source: NASA.Gov