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Forum:Exploration: Moon to Mars
Topic:Inflatable Decelerator low Earth orbit test
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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."

Robert PearlmanNASA updates during the LOFTID deploy and descent:
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.

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