Different tracking engine
Earth satellites use CelesTrak orbital elements and SGP4. Interplanetary spacecraft use NASA/JPL Horizons vectors because TLE/SGP4 is not the correct model for deep-space trajectories.
DEEP SPACE
Track missions beyond Earth orbit
Explore Voyager, JWST and active interplanetary missions using NASA/JPL Horizons ephemerides. Deep-space spacecraft are kept separate from Earth-orbit SGP4 tracking.
MISSION DIRECTORY
Deep-space spacecraft
NASA/JPL
Voyager 1
The most distant human-made spacecraft, continuing its interstellar mission beyond the heliopause.
Interstellar spaceOpen tracker →
NASA/JPLVoyager 2
The only spacecraft to have visited Uranus and Neptune, now continuing through interstellar space.
Interstellar spaceOpen tracker →
NASA/ESA/CSAJames Webb Space Telescope
A large infrared observatory operating in a halo orbit around the Sun–Earth L2 region.
Sun–Earth L2 regionOpen tracker →
NASANancy Grace Roman Space Telescope
NASA’s Nancy Grace Roman Space Telescope, currently commissioning while travelling from Earth toward the Sun–Earth L2 region.
Sun–Earth L2 regionOpen tracker →
NASANew Horizons
The Pluto and Kuiper Belt mission continuing through the outer solar system.
Kuiper BeltOpen tracker →
NASAParker Solar Probe
A solar mission repeatedly flying through the Sun’s outer corona to study the solar wind and energetic particles.
Inner heliosphere / SunOpen tracker →
ESA/NASASolar Orbiter
A solar observatory studying the Sun and heliosphere, including high-latitude views of the solar poles.
SunOpen tracker →
ESA/JAXABepiColombo
A joint ESA/JAXA mission in its Mercury arrival phase, designed to study the innermost planet.
MercuryOpen tracker →
ESAJUICE
The Jupiter Icy Moons Explorer is travelling to the Jupiter system to study Ganymede, Callisto and Europa.
Jupiter systemOpen tracker →
NASAEuropa Clipper
A mission travelling to Jupiter for repeated close flybys of Europa.
Jupiter / EuropaOpen tracker →
NASALucy
A multi-target mission to primitive asteroids, including Jupiter’s Trojan populations.
Jupiter Trojan asteroidsOpen tracker →
NASAPsyche
A mission travelling to the metal-rich asteroid Psyche in the main asteroid belt.
Asteroid 16 PsycheOpen tracker →
ESAHera
ESA’s planetary-defence mission travelling to survey the Didymos binary asteroid system after the DART impact.
Didymos / DimorphosOpen tracker →
Ephemeris snapshots
Deep-space coordinates are retrieved server-side and cached to reduce load. Distances and vectors are presented as ephemeris-derived values, not direct spacecraft telemetry.
Scale
The interactive scene uses a compressed visual scale so nearby and extremely distant missions can be viewed on one screen. Numeric distances remain the authoritative values.
DEEP-SPACE GUIDE
Deep Space Mission Tracking: Why Ephemerides Replace TLEs Beyond Earth Orbit
The Deep Space directory brings interplanetary and distant observatory missions into one place. These spacecraft cannot be treated like ordinary Earth satellites. Instead of using an Earth-centred TLE/SGP4 workflow, SpaceTracker.live queries NASA/JPL Horizons for time-tagged position and velocity vectors and presents an educational visualization of the mission's changing geometry.
What is an ephemeris?
An ephemeris is a table or service describing the predicted or reconstructed position of an astronomical object or spacecraft at specified times. JPL Horizons can provide vectors for planets, moons, asteroids, comets and many spacecraft. The result depends on the requested target, observer or reference centre, coordinate system and time span.
SpaceTracker.live caches ephemeris snapshots to reduce repeated upstream requests and then interpolates displayed values between time points. The changing numbers should therefore be read as ephemeris-derived calculations, not as a one-second radio telemetry stream from the spacecraft.
Why SGP4 is not used here
SGP4 is designed for Earth-orbiting objects represented by compatible general-perturbations orbital elements. A spacecraft travelling to Jupiter, an asteroid, Mercury or interstellar space is following a heliocentric or multi-body trajectory that cannot be represented meaningfully by the same Earth-satellite model. Keeping the two systems separate prevents a visually attractive but scientifically wrong calculation.
Understanding Earth distance, Sun distance and light time
Earth distance tells you how far the spacecraft is from our planet at the displayed epoch. Sun distance is heliocentric distance. These numbers can change in different directions because Earth itself moves around the Sun. One-way light time converts distance into communication delay at the speed of light and helps explain why commanding distant spacecraft is never instantaneous.
For a mission such as Voyager 1, light time is measured in many hours; for JWST near the Sun–Earth L2 region, it is only a few seconds. Comparing missions makes the scale of the solar system much easier to grasp.
Compressed scale in the visualization
A true linear-scale scene that contained the Sun, Earth and a very distant probe would make planets and nearby regions too small to see. The visual scene therefore compresses distances for exploration. The numerical distance, vector and light-time fields are the values to use when comparing missions.
Explore missions by destination
The directory includes missions toward the outer solar system, the Sun, Mercury, Jupiter and asteroids, together with observatories near the Sun–Earth L2 region. Open individual pages for mission-specific history, tracker limitations, educational questions and links to the responsible space agency.
For Earth-orbiting spacecraft, return to the Satellite Directory, use Satellites Above Me, or open the ISS Live Tracker to compare the SGP4 interface with an ephemeris-based deep-space page.
Frequently asked questions
Is the deep-space position direct spacecraft telemetry?
No. The displayed trajectory values are derived from NASA/JPL Horizons ephemerides.
Why can the visual distance look wrong?
The scene intentionally compresses scale so objects separated by radically different distances can remain visible together.
Why does Earth distance change even when a spacecraft is moving outward?
Earth is moving around the Sun too, so the separation between Earth and a spacecraft can increase or decrease independently of heliocentric distance.
Source and methodology links
Educational-use note: SpaceTracker.live is an independent educational website. Positions and pass predictions are calculated from third-party orbital elements or ephemerides and may be delayed or approximate. Do not use them for navigation, collision avoidance or other safety-critical decisions.
Choose a mission by scientific question
Voyager 1 and Voyager 2 are valuable for comparing separate paths into interstellar space; New Horizons connects the Pluto flyby with exploration beyond Neptune. Parker Solar Probe and Solar Orbiter investigate the Sun using different observing strategies. Webb and Roman are observatories associated with the Sun–Earth L2 region, while Europa Clipper and Juice address the science of icy moons from different mission designs. BepiColombo explores Mercury, Lucy visits asteroid populations linked to Jupiter, Psyche targets a metal-rich asteroid, and Hera follows the planetary-defence experiment at Didymos.
Why the same live measurements appear across different missions
Every deep-space tracker needs a shared language for comparison: position at a specified time, separation from Earth and Sun, one-way light time, and a reference frame. These measurements are meaningful only with a data source and timestamp. A craft may be closer to Earth today without having reversed its overall outward journey, because Earth is also moving. Compressed orbit scenes communicate relationships over enormous scales but must not be measured as if the marker size represented a real spacecraft.
Finding a target from your own location
Choose a sitewide observing location before opening a mission page. The observer guide then requests a separate Earth-based JPL Horizons calculation for direction, altitude and an ephemeris table where that target and date range are supported. A rise time marks a geometric horizon crossing; it is not a visibility forecast. Many interplanetary probes are too faint for ordinary visual observation. If an official ephemeris cannot be obtained, the guide shows unavailable data instead of inventing a position or predicting an encounter.
How to read the mission history
Launches and completed flybys are historical events; future gravity assists, arrivals and investigations are plans that can change. Mission science findings come from instrument teams and should be checked against NASA, ESA and JAXA updates. A position tracker is useful for placing that history in space and time, but it is not a direct stream of instrument images or a real-time mission control display. Start with a mission card, compare the live data with its reference article, and use its official source links when checking new scientific claims.