juliensimon/huygens-titan-atmosphere

Huygens Probe — Titan Atmospheric Profile

Part of the [Space Probe and Mission Datasets](https://huggingface.co/collections/juliensimon/space-probe-and-mission-datasets-69c3fe82d410a42b1e313167) 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

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