Engineering topics

Santos, Jose A.

Publications and source records attributed to Santos, Jose A..

6 records

NASA NTRS2019

White Papers for the Next Decadal Survey: Thermal Protection Systems and Instrumentation

NASA is anticipated to commission the next Planetary Science Decadal Survey (PSDS) with preparation expected in early calendar year 2020. The new PSDS will outline the priorities of science missions for the decade spanning 2023-2032. For the previous PSDS, the science and technology communities have been invited to submit white papers to the PSDS sub-panels as background information to guide the PSDS recommendations. The National Research Council has previously stated that white papers that represent the opinion of many authors from different institutions carried more significance and weight, and the recommendations from the previous PSDS attempted to reflect more of a consensus opinion. In 2009, a total of 4 white papers were submitted to the PSDS panels regarding thermal protection system (TPS) readiness for missions, as well as one on TPS instrumentation. The TPS readiness papers were co-authored by 90 individuals from many institutions. These white papers surveyed the TPS materials for both forebody and afterbody of a probe and analyzed the suitability of materials for missions to each destination. In addition, each paper outlined the ground testing required and ongoing technology development. Recommendations were provided for further technology development and ground test capability in order to fulfill future missions. Many improvements and changes have occurred in the past 10 years with regard to TPS materials and instrumentation. New materials have been developed and tested, such as the high density material Heat-shield for Extreme Entry Environment Technology (HEEET), and new capabilities for ground testing for high heating and high pressures have been added such as the 3-inch nozzle at the Ames arc jet. NASA has also flown several TPS instrumentation suites, such as MEDLI (Mars Science Laboratory Entry, Descent, and Landing Instrument) and EFT-1 (Exploration Flight Test-1). In order to provide the PSDS sub-panels with the most current information about the state-of-the-art suitability for TPS materials for entry missions, we are beginning to update and draft new white papers. We will present the outline for material to be covered in the white papers, and we invite all IPPW (International Planetary Probe Workshop) attendees to particiate in co-authoring these papers.

Hwang, Helen H.↗

NASA NTRS2016

Mars 2020 Entry, Descent and Landing Instrumentation 2 (MEDLI2)

The Mars Entry Descent and Landing Instrumentation 2 (MEDLI2) sensor suite will measure aerodynamic, aerothermodynamic, and TPS performance during the atmospheric entry, descent, and landing phases of the Mars 2020 mission. The key objectives are to reduce design margin and prediction uncertainties for the aerothermal environments and aerodynamic database. For MEDLI2, the sensors are installed on both the heatshield and backshell, and include 7 pressure transducers, 17 thermal plugs, and 3 heat flux sensors (including a radiometer). These sensors will expand the set of measurements collected by the highly successful MEDLI suite, collecting supersonic pressure measurements on the forebody, a pressure measurement on the aftbody, direct heat flux measurements on the aftbody, a radiative heating measurement on the aftbody, and multiple near-surface thermal measurements on the thermal protection system (TPS) materials on both the forebody and aftbody. To meet the science objectives, supersonic pressure transducers and heat flux sensors are currently being developed and their qualification and calibration plans are presented. Finally, the reconstruction targets for data accuracy are presented, along with the planned methodologies for achieving the targets.

Aerodynamics↗

NASA NTRS2016

Mars 2020 Entry, Descent and Landing Instrumentation 2 (MEDLI2)

This paper introduces the Mars Entry Descent and Landing Instrumentation 2 (MEDLI2) concept for NASAs Mars 2020 mission. Mars 2020 is a flagship-class mission, scheduled for launch in 2020, with science and technology objectives to help answer questions about habitability of Mars as well as to demonstrate technologies for future human expedition. MEDLI2 is a suite of instruments embedded in the heatshield and backshell thermal protection systems (TPS) of the Mars 2020 entry vehicle. The objectives of MEDLI2 are to gather critical aerodynamics, aerothermodynamics and TPS (Thermal Protective System) performance data during the Entry Descent and Landing (EDL) phase of the mission.

Aerothermodynamics↗

NASA NTRS2014

Mars Science Laboratory (MSL) Entry, Descent, and Landing Instrumentation (MEDLI): Complete Flight Data Set

The Mars Science Laboratory (MSL) entry vehicle (EV) successfully entered the Mars atmosphere and landed the Curiosity rover safely on the surface of the planet in Gale crater on August 6, 2012. MSL carried the MSL Entry, Descent, and Landing (EDL) Instrumentation (MEDLI). MEDLI delivered the first in-depth understanding of the Mars entry environments and the response of the entry vehicle to those environments. MEDLI was comprised of three major subsystems: the Mars Entry Atmospheric Data System (MEADS), the MEDLI Integrated Sensor Plugs (MISP), and the Sensor Support Electronics (SSE). Ultimately, the entire MEDLI sensor suite consisting of both MEADS and MISP provided measurements that were used for trajectory reconstruction and engineering validation of aerodynamic, atmospheric, and thermal protection system (TPS) models in addition to Earth-based systems testing procedures. This report contains in-depth hardware descriptions, performance evaluation, and data information of the three MEDLI subsystems.

Cheatwood, F. McNeil↗

NASA NTRS2014

AVCOAT Density Characterization for Orion Multi-Purpose Crew Vehicle

The Orion Multi-Purpose Crew Vehicle (MPCV) will transport four crew members to and from lunar-class orbital destinations. The first orbital Exploration Flight Test (EFT-1) is scheduled for December 2014 and will provide valuable data on several systems, including the heat shield. The heat shield material is AvcoatTM, a mid-density ablator. Specifically, the heat shield contains a fiberglass-phenolic honeycomb structure filled with an ablative epoxy novolac resin. Post-flight characterization of the EFT-1 thermal protection system will be conducted in order to study the material response and measure the char front of the material. Avcoat density profiling will be conducted to study three critical material zones: char, pyrolysis, and virgin states as a function of material depth. As part of a ground test campaign, Avcoat coupons are tested at the NASA Ames Research Center Arc Jet Complex. The test campaign is set forth to study material response based on environments, perform Avcoat material density characterization, and compare the char depths from the HEAT sensor and density profiling studies. These investigations will then be compared to flight data in order to improve upon TPS material response models.

AVCOAT↗

NASA NTRS2011

Isotherm Sensor Calibration Program for Mars Science Laboratory Heat Shield Flight Data Analysis

Seven instrumented sensor plugs were installed on the Mars Science Laboratory heat shield in December 2008 as part of the Mars Science Laboratory Entry, Descent, and Landing Instrumentation (MEDLI) project. These sensor plugs contain four in-depth thermocouples and one Hollow aErothermal Ablation and Temperature (HEAT) sensor. The HEAT sensor follows the time progression of a 700 C isotherm through the thickness of a thermal protection system (TPS) material. The data can be used to infer char depth and, when analyzed in conjunction with the thermocouple data, the thermal gradient through the TPS material can also be determined. However, the uncertainty on the isotherm value is not well defined. To address this uncertainty, a team at NASA Ames Research Center is carrying out a HEAT sensor calibration test program. The scope of this test program is described, and initial results from experiments conducted in the laboratory to study the isotherm temperature of the HEAT sensor are presented. Data from the laboratory tests indicate an isotherm temperature of 720 C 60 C. An overview of near term arc jet testing is also given, including preliminary data from 30.48cm 30.48cm PICA panels instrumented with two MEDLI sensor plugs and tested in the NASA Ames Panel Test Facility. Forward work includes analysis of the arc jet test data, including an evaluation of the isotherm value based on the instant in time when it reaches a thermocouple depth.

Santos, Jose A.↗