juliensimon/huygens-titan-atmosphere

Huygens Probe — Titan Atmospheric Profile

Part of the Space Probe and Mission Datasets collection on Hugging Face.

Titan atmospheric profile measured by the Huygens Atmospheric Structure Instrument (HASI) during descent on January 14, 2005 (09:05:28--11:38:10 UTC). Currently 2,727 measurements spanning 0.0 to 1380.2 km altitude — the only in-situ atmospheric profile ever taken of Titan.

Dataset description

On January 14, 2005, the ESA Huygens probe separated from the Cassini orbiter and descended through Titan's atmosphere for approximately 153 minutes, from atmospheric entry at ~1,400 km altitude to touchdown on the surface. The Huygens Atmospheric Structure Instrument (HASI) measured pressure, temperature, and density throughout the descent.

The dataset combines two mission phases:

• Entry phase (911 measurements): Upper atmosphere (1380 km down to ~157 km), where pressure and temperature were derived from accelerometer deceleration data. Density was not directly measured during this phase.
• Descent phase (1,816 measurements): Lower atmosphere (~147 km to the surface at 0.0 km), where direct pressure/temperature sensors provided measurements after parachute deployment. Density was computed from pressure and temperature.

Vertical velocity from the trajectory reconstruction is merged for each measurement point.

Surface conditions at landing: 1466.5 hPa pressure, 93.5 K temperature.

Schema

Column	Type	Description
utc_time	datetime	Measurement timestamp (UTC)
mission_elapsed_time_s	float64	Seconds since atmospheric entry (T0 = 09:05:28 UTC)
phase	string	Mission phase: "entry" (upper atmosphere) or "descent" (parachute phase)
altitude_m	float64	Altitude above surface (meters)
altitude_km	float64	Altitude above surface (kilometers)
pressure_pa	float64	Atmospheric pressure (Pascals)
pressure_hpa	float64	Atmospheric pressure (hectopascals / millibars)
temperature_k	float64	Atmospheric temperature (Kelvin)
density_kg_m3	float64	Atmospheric density (kg/m^3) — null during entry phase
velocity_m_s	float64	Probe vertical velocity (m/s)

Quick stats

• 2,727 atmospheric measurements (911 entry + 1,816 descent)
• Altitude range: 0.0 to 1380.2 km
• Temperature range: 70.3 to 207.2 K
• Surface conditions: 1466.5 hPa, 93.5 K
• Duration: 153 minutes of atmospheric profiling

Usage

from datasets import load_dataset

ds = load_dataset("juliensimon/huygens-titan-atmosphere", split="train")
df = ds.to_pandas()

# Temperature profile
import matplotlib.pyplot as plt
plt.plot(df["temperature_k"], df["altitude_km"])
plt.xlabel("Temperature (K)")
plt.ylabel("Altitude (km)")
plt.title("Titan Atmospheric Temperature Profile")
plt.show()

# Entry vs descent phase
entry = df[df["phase"] == "entry"]
descent = df[df["phase"] == "descent"]
print(f"Entry: {len(entry)} pts, {entry['altitude_km'].min():.0f}-{entry['altitude_km'].max():.0f} km")
print(f"Descent: {len(descent)} pts, {descent['altitude_km'].min():.0f}-{descent['altitude_km'].max():.0f} km")

# Pressure-temperature diagram
plt.semilogy(df["temperature_k"], df["pressure_hpa"])
plt.xlabel("Temperature (K)")
plt.ylabel("Pressure (hPa)")
plt.gca().invert_yaxis()
plt.title("Titan P-T Profile")
plt.show()

Data source

NASA PDS Atmospheres Node — Huygens HASI Archive (Volume hphasi_0001, Level 4 calibrated profiles).

Original instrument paper: Fulchignoni, M. et al., "In situ measurements of the physical characteristics of Titan's environment," Nature, 438, 785--791 (2005).

Related datasets

• cassini-saturn-observations — Cassini orbiter observation log
• deep-space-probes — Voyager & Pioneer merged hourly data
• mars-perseverance-weather — Mars atmospheric measurements

Pipeline

Source code: juliensimon/space-datasets

Support

If you find this dataset useful, please give it a ❤️ on the dataset page and share feedback in the Community tab! Also consider giving a ⭐️ to the space-datasets repo.

Citation

@dataset{huygens_titan_atmosphere,
  author = {Simon, Julien},
  title = {Huygens Probe — Titan Atmospheric Profile},
  year = {2026},
  publisher = {Hugging Face},
  url = {https://huggingface.co/datasets/juliensimon/huygens-titan-atmosphere},
  note = {Based on ESA/NASA Huygens HASI Level 4 calibrated atmospheric profiles from the PDS Atmospheres Node}
}

License

CC-BY-4.0