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HelioSPICE

Retrieve spacecraft ephemerides, distances, and coordinate transforms using automatically managed NAIF SPICE kernels.

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Install HelioSPICE

Pick your client, then add it in one click or paste the config.

STDIOPython
~/Library/Application Support/Claude/claude_desktop_config.json
claude_desktop_config.json
{
  "mcpServers": {
    "heliospice": {
      "command": "uvx",
      "args": [
        "xhelio-spice"
      ],
      "env": {
        "XHELIO_SPICE_KERNEL_DIR": "YOUR_VALUE_HERE"
      }
    }
  }
}

Settings → Developer → Edit Config, merge this into mcpServers, then fully quit and reopen Claude Desktop.

Values are written into the snippet above so you can paste it as is. They never leave your browser.

We couldn’t confirm it starts correctly

We ran the install command but it didn't respond within our test window — this can mean a slow first-time install rather than a real problem.

uvx xhelio-spice

Process exited before answering initialize.

This is an experimental automated check and can have false negatives — missing environment variables, a slow cold install, etc. It doesn’t necessarily mean something’s wrong. Last checked Today.

Overview

HelioSPICE MCP server exposes heliophysics ephemeris operations through MCP, using SpiceyPy and NAIF SPICE kernels behind the scenes. It can return position and velocity for a single time or a timeseries, calculate distances, transform coordinate frames, and inspect missions, frames, and kernel cache state. Kernels are downloaded on first use and stored locally, so reach for it when an agent needs spacecraft or natural-body geometry without manually assembling SPICE kernel files.

Use cases

  • Query spacecraft position and velocity at a specified time
  • Generate trajectory timeseries for a heliophysics mission
  • Calculate distance between a spacecraft and natural body
  • Transform vectors between SPICE coordinate frames
  • Inspect and maintain the local kernel cache

Key features

  • Automatic NAIF kernel downloading and caching
  • Single-time and timeseries ephemeris queries
  • Spacecraft and natural-body distance calculations
  • Coordinate-frame transformations
  • Mission and frame discovery
  • Kernel cache management

Tools6

What HelioSPICE lets your agent do. Expand a tool for its parameters.

Self-reported~73 tokens of context

Security & health

What it can reach and how reliably it runs — from our own checks, not the maintainer’s claims.

ActiveLast checked 2d ago

Recent health check succeeded.

4/4 checks healthy over the last 42d

Supply-chain signal

No high-severity advisories surfaced by our automated scan.

Critical 0High 0Medium 0Low 0

Scanned 16d ago via OSV.dev · xhelio-spice (PyPI)

Adoption & maintenance

Factual signals from GitHub, npm, and our automated checks — not a rating.

Last commit4mo agoMost recent push to the default branch.
Install checkInconclusiveDidn't respond in our test window — often a slow first install.
Tools exposed6Callable tools this server registers over MCP.
Directory activity1 viewsConfig copies, upvotes, and views on AllMCPs.

How HelioSPICE works

What HelioSPICE MCP server does

The HelioSPICE MCP server gives MCP-compatible agents access to spacecraft and planetary geometry from NAIF SPICE data. It wraps the xhelio-spice Python package and SpiceyPy, handling kernel retrieval, loading, and caching so callers can request ephemerides without managing the underlying files directly.

Position and velocity queries can target a single timestamp or produce a timeseries in CSV form. Other operations calculate the distance between two bodies and convert vectors between supported coordinate frames. The server also exposes discovery tools for supported missions and coordinate frames, plus operations for inspecting or managing the local kernel cache.

How it works

On the first request that needs mission data, xhelio-spice downloads the relevant kernels from NAIF and caches them locally. It loads the kernels in the required order before performing the SPICE calculation. Results are returned through MCP tool responses; the underlying Python API can also represent individual results as dictionaries and trajectory data as pandas DataFrames.

Queries can refer to supported spacecraft, natural bodies, observers, timestamps, and frames. Examples in the package documentation use Parker Solar Probe, the Sun, Earth, Saturn, J2000, ECLIPJ2000, GSE, and RTN. RTN transformations require a spacecraft parameter.

Setup and configuration

Install the base package with pip:

Terminal
pip install xhelio-spice

Install MCP support with the optional extra:

Terminal
pip install 'xhelio-spice[mcp]'

Start the stdio server with xhelio-spice-mcp, or run python -m xhelio_spice.server. The default kernel directory is ~/.xhelio_spice/kernels/. Set XHELIO_SPICE_KERNEL_DIR to use a different cache location. The Python API also supports a per-instance kernel_dir override through KernelManager.

Tools and capabilities

The HelioSPICE MCP server advertises six tools:

  • get_ephemeris returns position and velocity for one time or a timeseries as CSV.
  • compute_distance calculates the separation between two bodies.
  • transform_coordinates transforms a vector between coordinate frames.
  • list_spice_missions reports supported missions.
  • list_coordinate_frames lists available frames with descriptions.
  • manage_kernels handles kernel-cache operations.

Auto-downloaded kernel support is documented for Parker Solar Probe, Solar Orbiter, STEREO-A, Juno, Voyager 1 and 2, and New Horizons. Natural bodies include the Sun, Earth, Moon, the other planets, and Pluto. Several additional missions have NAIF IDs but do not currently receive automatic downloads.

Limitations and notes

Mission support is not uniform. ACE, Wind, DSCOVR, and MMS are listed without public SPK kernels for automatic download. Cassini and MAVEN require multi-segment kernel loading, which is identified as planned, while several other missions are listed as NAIF-ID-only. Requests for those missions may therefore require capabilities not currently covered by automatic kernel management.

Kernel downloads occur on first use, so network access may be needed before a requested mission can be calculated. The package provides a CI-safe smoke test that starts the stdio server with an isolated temporary cache and checks initialization and advertised tool names without requesting kernel downloads.

Read the full README View source on GitHub

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Frequently Asked Questions about HelioSPICE

HelioSPICE is an MCP server that connects AI tool use to SpiceyPy and NAIF SPICE kernels for heliophysics spacecraft and natural-body ephemerides. Its main tools retrieve position and velocity, calculate distances, transform coordinate frames, list missions and frames, and manage the local kernel cache.

Install it with `pip install 'xhelio-spice[mcp]'`. The MCP extra provides server support; after installation, start the service with `xhelio-spice-mcp` or `python -m xhelio_spice.server`.

HelioSPICE stores kernels by default in `~/.xhelio_spice/kernels/`. Set `XHELIO_SPICE_KERNEL_DIR` to override that directory, or provide `kernel_dir` when creating a Python `KernelManager` instance.

Install the MCP extra and configure Cursor to launch the stdio server using the installed `xhelio-spice-mcp` command.

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