{
  "title": "Reproduction data and method for the AEPS ETU-2 Hall-thruster results figure",
  "source": {
    "authors": "Jason D. Frieman et al.",
    "title": "Performance of the 12.5-kW Advanced Electric Propulsion System Engineering Test Unit Hall Thruster",
    "meeting": "2021 JANNAF Meeting, June 7–17, 2021",
    "nasa_ntrs_document_id": "20210015735",
    "url": "https://ntrs.nasa.gov/citations/20210015735",
    "pdf_url": "https://ntrs.nasa.gov/api/citations/20210015735/downloads/Frieman_%20Pres._2021%20JANNAF_ETU2%20Performance.pdf",
    "source_location": "Slide 9, PDF page 9 (zero-based PDF page index 8), table “Results: AEPS RFCs”; reported uncertainty row on that slide. Slide 10 separately labels a 95% confidence interval for mean thrust."
  },
  "extraction": "Transcribed the four AEPS reference firing conditions from the published table for ETU-2 and the predecessor HERMeS Technology Demonstration Unit (TDU). Discharge powers are stored as the exact table watt values (6250, 8333, 10417, 12500 W). No curve digitization, interpolation, or synthetic data.",
  "reported_uncertainties": {
    "thrust_mN": "±5 mN",
    "specific_impulse": "±0.9%",
    "total_efficiency": "±1.7%",
    "scope": "Slide 9 reports the nominal uncertainty row. The source slide 10 separately labels a 95% confidence interval for mean thrust; this graphic does not imply the specific-impulse or total-efficiency percentages are 95% confidence intervals."
  },
  "visualization": "Three aligned plots show source table values versus discharge power for ETU-2 and TDU. Points are measured reference conditions; connecting lines are visual guides only, not a fitted or predictive model. Error bars use the source-reported uncertainties: ±5 mN, and ±0.9%/±1.7% relative to each reported specific-impulse/efficiency value, respectively. Focused y-axis ranges are labeled with ticks; they do not start at zero. Wide and phone SVGs show identical values and differ marker shapes as well as colors.",
  "interpretation": "This is a laboratory-vacuum electric propulsion comparator that uses supplied electrical power and carried xenon propellant. It is not an air-breathing inlet or MHD recovery experiment and says nothing about recovering a hypersonic inlet’s flow energy.",
  "reproduction": "Run python generate_aeps_figure.py to regenerate the reference-condition graph from the exact p.9 table values. Run python reproduce_mean_thrust_ci.py to regenerate the separate slide-10 graph illustration from mean-thrust-95ci-visual-reading.csv. The second plot uses approximate visual readings, not raw source data or a recomputed confidence interval; both scripts require Python standard library only.",
  "rights": "NASA NTRS record 20210015735 marks the presentation Public Use Permitted. This is a styled redraw from its public slide, with visual estimates explicitly labeled; it does not imply NASA endorsement.",
  "mean_thrust_95_percent_confidence_interval_figure": {
    "source_location": "Frieman et al. (2021), NASA NTRS 20210015735, slide 10 / PDF page 10. The slide places the three-thruster mean-thrust chart under the stated contingency condition of 630 V / 13.1 kW.",
    "source_caption": "95% Confidence Interval for Mean Thrust",
    "reconstruction": "Styled redraw preserves the chart categories, 608–614 mN vertical range, point ordering and visible whisker geometry. Means and interval endpoints were estimated visually from the PDF plot because numerical values for this chart are not tabulated on the slide.",
    "data_file": "mean-thrust-95ci-visual-reading.csv",
    "data_status": "The CSV contains approximate visual readings only; it is not raw data, a transcription of source numerical values, or an independently computed interval.",
    "missing_information": [
      "sample counts",
      "individual thrust measurements",
      "confidence-interval calculation method",
      "full numerical means and endpoints"
    ],
    "interpretation_limit": "The presentation states that ETU-2 matched the HERMeS TDUs within empirical uncertainty. Axis and whisker overlap in this redraw are not an independent significance or equivalence test. The chart alone does not supply the data and method required for such a test.",
    "reproduction_script": "reproduce_mean_thrust_ci.py; reads approximate visual values from mean-thrust-95ci-visual-reading.csv; does not recompute uncertainty."
  },
  "current_program_context": {
    "as_of": "2026-10-05",
    "qualification": "NASA NTRS record 20250008681, last modified 2026-09-21, reports qualification testing on two thruster units in progress and expected completion in 2027. These are qualification ground tests, not flight results. NASA's SR-1 Freedom mission page, last updated 2026-09-29, now lists the 12-kW AEPS Hall thruster in the planned vehicle architecture; this is a mission plan, not evidence the thruster has flown.",
    "original_application": "Gateway PPE was the original planned application. NASA FY2026 budget materials describe Gateway close-out and potential transfer of already-produced hardware. The May 2026 directive realigned PPE decision authority and funding within SR-1 Freedom. NASA's current SR-1 Freedom page now explicitly lists a 12-kW AEPS Hall thruster and a bus identified as Power and Propulsion Element generating 48 kW. The same page separately lists a 20-kWe closed-Brayton power-conversion system; it does not reconcile these figures as one operating-point power chain.",
    "claim_boundary": "Describe Gateway as the original application and SR-1 Freedom as NASA's currently published planned application for a 12-kW AEPS Hall thruster. Do not treat the mission page as a completed assignment contract, qualification completion, flight demonstration or operating-power balance. Do not add or equate the separately listed 20 kWe, 48 kW and 12-kW figures.",
    "sources": [
      "https://ntrs.nasa.gov/citations/20250008681",
      "https://www.nasa.gov/mission/space-reactor-1-freedom/",
      "https://www.nasa.gov/wp-content/uploads/2025/05/fy-2026-budget-technical-supplement-002.pdf",
      "https://www.nasa.gov/blogs/workforce-updates/2026/05/22/a-message-from-administrator-jared-isaacman/"
    ]
  }
}