posted 08-10-2021 10:30 AM               

Inflatable Heat Shield One Step Closer to 2022 Demonstration

A NASA technology that could one day help land humans on Mars is about to head into final integration and testing before an orbital flight test next year.

Above: The flexible thermal protection system contains two outer surface layers made of ceramic fiber fabric, several layers of insulator, and then a gas barrier that prevents hot gases from getting to directly to the inflatable structure. The inflatable structure is a high temperature capable, flexible structure that is inflated to provide the cone shape that the FTPS drapes over. (NASA/Greg Swanson)

Two key components of the Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) are complete and recently arrived at NASA's Langley Research Center in Hampton, Virginia. At Langley, engineers will test the complete system to ensure LOFTID is flight ready.

The inflatable decelerator is scheduled to launch with a polar-orbiting satellite in September 2022. After the satellite makes its way to orbit, LOFTID will descend back to Earth from low-Earth orbit to demonstrate the inflatable aeroshell, or heat shield, can slow down and survive re-entry.

Hardware Progress

The flexible thermal protection system provides layers of material to protect the entire LOFTID re-entry vehicle from the extreme heat of atmospheric entry. It was built by Jackson Bond Enterprises, a small business in Dover, New Hampshire. In May, it was shipped to Airborne Systems in Santa Ana, California. That's where the inflatable structure, the stacked ring assembly that maintains the shape of the aeroshell, was built and tested. The two components were then integrated to make up the complete aeroshell and load tested to ensure the structures will perform as expected during flight.

Before shipping to Langley, the integrated components were painstakingly packed – an intensive process in which the aeroshell is gathered in a particular way, turned upside down, gathered again, cinched by hand, flipped again, and then put into a hydraulic ram. The ram is a machine that presses it until it is almost as dense as wood and can be restrained to this much smaller shape. The entire re-entry vehicle will be compressed into a configuration for shipping and launch that's about 4 feet in diameter by 7 feet long, compared to 20 feet in diameter by 5 feet long when deployed.

Next, the aeroshell will be integrated with the rest of the re-entry vehicle. The vehicle is comprised of several segments that link the inflatable structure to the inflation system, avionics, or flight electronics, ejectable data recorder, and parachute system.

The forward segment, which connects the inflatable structure to the inflation system, is complete. The inflation system, which will slowly expand the inflatable structure to shape before re-entry, is nearing completion. The team will install avionics into the inflation system and then stack it with the mid-segment, which contains the interface to the rocket, along with critical power, control, and data acquisition electronics. Then, the aft segment, which houses the ejectable data recorder, cameras, and the parachute system, will be assembled. Parts of the aft segment are already in work at Airborne where they're performing tests on the parachute system, at Langley and various contractors where its structures are being fabricated, and at NASA's Marshall Space Flight Center in Huntsville, Alabama, where the camera systems were completed and tested.

Above: This exploded view of the LOFTID re-entry vehicle shows each of the components that makes up the various segments. (NASA)

Later this year, all the components of the re-entry vehicle will be integrated and put through a battery of environmental tests in preparation for delivery to United Launch Alliance (ULA).

Mission Dedication

NASA and ULA are dedicating the LOFTID mission in honor of Mr. Bernard Kutter, manager of advanced programs at ULA, who passed away last year.

Bernard Kutter was not only an advocate for more commonplace access to space, but also the technologies that could make it a reality. The ULA engineer took a keen interest in NASA's inflatable heat shield design which could enable the safe return of rocket engines for re-use, as well as land large payloads on Mars required for crewed missions. He was instrumental in advancing the technology and developing the plan to test the system on an Atlas V rocket.

Above: The Bernard Kutter Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) is dedicated in honor of Mr. Kutter and his advocacy for space technology and more access to space. (ULA)

"I – like the rest of the aerospace community – was saddened to hear of Bernard's unexpected passing last summer," said Jim Reuter, associate administrator of NASA's Space Technology Mission Directorate. "Together, NASA and ULA cannot think of a better way to honor his contributions and legacy than to dedicate the first flight demonstration of this technology to him."

"Bernard was the cornerstone of ULA's Advanced Programs team, shaping the future of space technology and sharing that vision with many inside and outside of ULA," said Tory Bruno, ULA's president and CEO. "His influence can be seen everywhere from the Vulcan Centaur design to NASA's lunar architecture. He is greatly missed."

NASA and its partners continue to prepare the technology for the significant flight test next year.

"This represents almost 18 years of effort," said Joe Del Corso, LOFTID project manager at Langley. "LOFTID is the culmination of ground tests and a suborbital flight test leading up to an orbital entry test and the demonstration of Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology. This is the launching point for the next phase of a technology that will be critical to enabling human access to Mars."

Landing humans on Mars will require larger, heavier payloads than have ever been landed on the Red Planet. That will require a much larger heat shield than currently exists. A scaled-up HIAD could provide the drag area and heat protection needed for a human Mars mission. In addition, HIAD technology could allow landing at higher altitude locations, enable better use of the full volume of rockets, provide heavy payload return from low-Earth orbit, and lower the cost of access to space through launch vehicle asset recovery.

"Bernard advocated for us everywhere. I think the LOFTID project would not have happened without Bernard, and that's one of the reasons the dedication is for him," said Dr. Neil Cheatwood, LOFTID principal investigator.

The LOFTID project is a part of the Technology Demonstration Missions program within NASA's Space Technology Mission Directorate. The project is managed by Langley with contributions from NASA's Ames Research Center in Silicon Valley, Marshall Space Flight Center in Huntsville, Alabama, and Armstrong Flight Research Center in Edwards, California.

posted 11-08-2022 12:25 PM               

Equipping LOFTID's Sensors for a Fiery Descent Back to Earth

NASA has its sights set on sending humans to Mars in the coming decades and sending spacecraft even farther out in our solar system. These increasingly complex missions require more capable technologies to enable safe passage for cargo, complex payloads, and even people on the dangerous dash through a planet's atmosphere to reach the surface.

Above: Engineer Joseph Williams assesses thermocouples inside the centerbody of LOFTID's aeroshell. LOFTID is equipped with 100 thermocouples to measure temperature during the flight test. (NASA/Cole Kazemba)

To develop that capability, NASA's Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) mission will test a new heat shield designed to inflate to protect heavier payloads on the journey through an atmosphere. A heat shield protects a spacecraft during the fiery descent, where temperatures can reach levels up to half the temperature of the Sun's surface. During LOFTID's test mission, a suite of sensors on the re-entry vehicle will collect data to help researchers understand how it performed during the flight.

"The data is the star of the show," said Greg Swanson, instrumentation lead for LOFTID at NASA's Ames Research Center in California's Silicon Valley. "Learning how this inflatable heat shield performs in these extreme conditions is exactly how we scale this technology up to one day take humans and their cargo to Mars."

NASA's Langley Research Center in Hampton, Virginia, leads the LOFTID mission, with contributions from other NASA centers. LOFTID's instrumentation development, including designing, procuring, calibrating, and testing all of the sensors on the vehicle, is led by NASA Ames.

A Comprehensive Instrument Suite

LOFTID's main goal is to demonstrate one of the most difficult parts of spaceflight, atmospheric entry, with a new piece of technology that may one day be used to protect humans on a trip to another world. During this demonstration mission, LOFTID's suite of state-of-the-art sensors will monitor the vehicle's experience and capture data in two recorders – one that will stay with the craft through splashdown and a backup that will eject from the craft during re-entry. Researchers and engineers will use that information to improve future designs.

Traversing through an atmosphere to land on another world or return to Earth from orbit takes a spacecraft to extreme speeds, generating a tremendous amount of heat due to both the convection of hot gas flowing around the spacecraft and the radiation created by the shockwave that forms. The spacecraft must withstand changes in pressure, heat rate, temperature, and more. The instruments on board must be able to account for all these shifting variables.

The instrument suite for LOFTID is comprehensive. Pressure sensors and strap loadcell pins will characterize the total force felt by the spacecraft. Total heat flux gauges measure energy transfer, capturing detailed readings across the body of the craft. A radiometer will measure the spacecraft's exposure to radiation as a result of the gas ionization induced by the hypersonic shockwave. One hundred thermocouples will monitor temperatures all across the vehicle.

LOFTID will also use a parachute to break its fall into the Pacific Ocean and an "up look" camera installed at the top of the vehicle will capture launch vehicle separation and monitor parachute deployment for later review by the research team.

LOFTID's instrumentation was developed through the partnership and expertise of multiple NASA centers across the country in addition to NASA Ames, including Langley Research Center, Marshall Spaceflight Center, and Armstrong Flight Research Center. These include GPS systems, experimental temperature sensors, specialized cameras, and more. The mission team designed a tailored package of instruments to collect ample data on LOFTID's perilous journey, but they also needed to make sure the sensors would survive the trip themselves.

Testing and Calibrating for Extreme Temperatures

Above: This view of LOFTID's nose shows the re-entry vehicle's radiometer (center) and four total heat flux gages (top, right, bottom, left) that will be used to measure the radiative component of the heat flux and the overall heat rate, respectively. Each of these sensors also includes a port that allows pressure transducers to measure the aerodynamic pressure on the vehicle's surface. (NASA/Greg Swanson)

The LOFTID spacecraft is designed to withstand the dangerous journey through Earth's atmosphere from low-Earth orbit, and the instruments on board have to be equally resilient. Researchers at Ames took the lead on testing and calibrating LOFTID's instruments and found two concerns that were addressed prior to launch.

One was related to the radiometers and total heat flux gauges, which measure radiation and energy transfer. During testing, the Ames Sensors and TPS Advanced Research (STAR) Laboratories conducted calibration that indicated discrepancies in sensor readings and successfully re-calibrated the instruments with improved techniques for more accurate readings.

A second fix was related to the materials used for the 100 thermocouple sensors across the spacecraft. Early tests found that thermocouples in several key locations in LOFTID's original configuration might not perform properly in expected flight environments. Using a tube furnace facility at Ames, a new configuration was developed. The performance of this new configuration was verified at conditions that replicate atmospheric re-entry via testing at the Boeing Large Core Arc Tunnel facility in St. Louis. This testing ensured the sensors could safely and accurately collect data on the trip.

"Bringing anything through an atmosphere from space is difficult, especially at this scale and on worlds like Mars, Titan, and Venus," said Cole Kazemba, LOFTID aeroshell instrumentation lead at Ames. "But by doing what LOFTID's doing now – collecting data, testing on the ground and then in flight, learning and scaling up – NASA is making sure that, when we're ready, we'll be able to safely land on our destinations near and far."

posted 11-10-2022 08:02 AM               

LOFTID Technology Demonstration Begins

United Launch Alliance's Centaur upper stage has successfully powered on the LOFTID re-entry vehicle, kicking off the LOFTID mission sequence. About two minutes after power on, Centaur released the payload adapter that had connected JPSS-2 to the rocket's upper stage.

Limited data will be received real-time during the technology demonstration. Other milestones are notional given the mission timeline and sequence.

Aeroshell Inflates

Aeroshell inflation has started. Once the aeroshell reaches four pounds per square inch (psi) of pressure, Centaur will begin positioning LOFTID for re-entry.

LOFTID Separates From Centaur Upper Stage

After orienting LOFTID to an acceptable separation angle, Centaur spun up and released the re-entry vehicle. Spinning at three rotations per minute keeps the LOFTID vehicle stable and pointed in the right throughout re-entry.

LOFTID Aeroshell Fully Inflated; Re-entry in 25 Minutes

At this time, the aeroshell should have reached a full inflation pressure of 19 psi. LOFTID is only sending limited real-time data during the demonstration. Full data, including confirmation of the final inflation pressure, will be confirmed after landing and recovery.

LOFTID is now coasting toward the atmosphere and re-entry is expected to start in approximately 25 minutes.

LOFTID Re-entry Begins

The team was able to visually confirm full inflation of the re-entry vehicle. LOFTID is now estimated to be at about 78 miles in altitude, the point the LOFTID team considers the start of atmospheric re-entry.

LOFTID Reaches Maximum Re-entry Heating

Over the past few minutes, LOFTID's thermal protection system should have reached maximum re-entry heating, and the inflatable structure should have reached maximum re-entry pressure load.

LOFTID is only sending limited real-time data during the demonstration. Full data, including the maximum heating and pressure load experienced, will be confirmed after landing and recovery.

End of LOFTID Technology Demonstration

According to the team's predictions, LOFTID should have slowed down to Mach 0.7 — from a maximum speed of Mach 29 — marking the end of the demonstration and data collection. As LOFTID approaches splashdown in approximately 16 minutes, the ejectable data module will jettison and the parachute will deploy.

LOFTID's Parachutes Have Deployed

Teams confirmed the ejectable data recorder jettisoned and have received GPS data on its location. LOFTID's parachutes are expected to have deployed, preparing LOFTID for splashdown in less than 10 minutes.

Splashdown! LOFTID Set for Retrieval in the Pacific

LOFTID has splashed down in the Pacific Ocean hundreds of miles off the coast of Hawaii. Once the aeroshell's location is determined, the recovery boat will head towards the aeroshell for attempted retrieval. Following retrieval, the team will recover the ejectable data recorder.

LOFTID Splashdown Confirmed

The LOFTID team has visually confirmed the heat shield's splashdown in the Pacific Ocean. Splashdown occurred a few minutes later than originally thought based on the expected mission timeline.

Team Continues to Monitor Telemetry Data

At this time, the team has not yet received data to confirm solar array deployment. There may not be an issue, but we're monitoring closely as more telemetry data becomes available.

LOFTID Recovery Underway

LOFTID landed close to the recovery ship. After assessing the situation, the crew aboard the Kahana-II have begun preparation for recovery operations, which will bring LOFTID aboard the vessel. NASA will post updates on the recovery process and the results of the demonstration as more information becomes available.