ACEP Public Telemetry
Public-access telemetry presenting selected mission parameters, trajectory state, and event markers for high-level mission monitoring.
View ACEP Public TelemetryACEP
The Alpha Centauri Exploratory Probe (ACEP) is an uncrewed interstellar spacecraft and the first operational vehicle within the 1gSpace mission architecture.
Operating under a continuous 1 g acceleration-deceleration profile, it departed on January 1, 2025 and is scheduled to arrive on July 12, 2028, where it will transition from cruise validation to orbital scientific operations.
Although distinct from the later mission vehicles in scale and configuration, ACEP applies the same broader architectural principles and serves as the program’s first in-flight validation of interstellar propulsion, autonomy, and long-duration systems behavior.
ACEP Premium Access
Full-resolution operational telemetry exposing internal subsystem states, derived metrics, and control behavior across all mission phases.
View ACEP Premium AccessACEP Documentation
Technical reference describing ACEP vehicle architecture, propulsion, power, thermal control, communications, and mission design.
View PDFMission Role
Following orbital arrival, ACEP is tasked with characterizing the local operational environment, including orbital conditions, surface context, and atmospheric properties relevant to subsequent crewed and logistical mission stages.
The primary science phase is concentrated in the initial months after arrival, during which the vehicle performs sustained remote sensing, environmental assessment, and mission-context observation while operating fully autonomously under deep-space communication delays.
In addition to orbital measurements, the dedicated ACEP Atmos descent element performs a controlled atmospheric entry sequence, transmitting in-situ pressure, temperature, and composition data, together with descent-phase observational data, prior to terminal loss.
After completion of the primary science window, ACEP is capable of extended low-power orbital persistence, preserving a long-duration observation and telemetry asset while continuing to support architectural, environmental, and operational baseline definition.
ACEP Milestones
Click on each category for details.
Speed Achievements
- Minute 3 - ACEP achieved the speed of the X-15 Rocket Plane (4,520 km/h)
- Minute 4 - ACEP achieved Space Shuttle re-entry speed (7,800 km/h)
- Minute 9 - ACEP reached the escape velocity of Voyager 1 (17,000 km/h)
- Minute 17 - ACEP achieved the speed of Apollo 10 during re-entry (39,600 km/h)
- Minute 19 - ACEP reached the speed of Apollo 11 during lunar insertion (10.8 km/s)
- Minute 19 - ACEP reached the escape velocity achieved by Saturn V (40,000 km/h)
- Minute 20 - ACEP achieved Earth escape velocity (11.2 km/s)
- Minute 24 - ACEP achieved the speed of New Horizons during its Pluto flyby (50,000 km/h)
- Minute 28 - ACEP reached the speed of the Galileo spacecraft (73,000 km/h)
- Minute 29 - ACEP reached the speed of Voyager 1, the fastest probe leaving the Solar System (17.0 km/s)
- Minute 51 - ACEP reached Earth's orbital speed around the Sun (107,226 km/h)
- Minute 72 - ACEP achieved Solar escape velocity (42.1 km/s)
- Hour 3 - At this speed (107 km/s), ACEP would cover Earth-Moon distance in ~1 hour.
- Hour 4 - ACEP achieved the speed of the Parker Solar Probe (163 km/s), the fastest man-made object to date
- Hour 19 - At this speed (667 km/s), ACEP would circumnavigate Earth in 1 minute.
- Day 4 - ACEP reached 1% of light speed (305,910 seconds)
- Day 8 - At this speed (6407 km/s), ACEP would cover Earth-Moon distance in 1 minute.
- Day 12 - At this speed (10556 km/s), ACEP would cover Earth-Venus distance in 1 hour.
- Day 16 - At this speed (13900 km/s), ACEP would cover Earth-Saturn distance in 1 day.
- Day 25 - At this speed (21389 km/s), ACEP would cover Earth-Mercury distance in 1 hour.
- Day 33 - At this speed (27800 km/s), ACEP would cover Earth-Saturn distance in 12 hours.
- Day 36 - ACEP attained 10% of light speed. At this speed (30560 km/s), ACEP would cover Earth-Mars distance in 30 minutes.
- Day 46 - At this speed (38400 km/s), ACEP would cover the Earth-Moon distance in 10 seconds.
- Day 47 - At this speed (40000 km/s), ACEP would circumnavigate Earth in 1 second.
- Day 50 - At this speed (41667 km/s), ACEP would cover Earth-Sun distance in 1 hour.
- Day 72 - ACEP attained 20% of light speed
- Day 82 - At this speed (68300 km/s), ACEP would cover Earth-Pluto distance in 1 day.
- Day 110 - ACEP attained 30% of light speed
- Day 150 - ACEP attained 40% of light speed
- Day 174 - At this speed (136700 km/s), ACEP would cover the Earth-Venus distance in 5 minutes.
- Day 195 - ACEP attained 50% of light speed
- Day 218 - At this speed (164000 km/s), ACEP would cover the Earth-Pluto distance in 10 hours.
- Day 222 - At this speed (166667 km/s), ACEP would cover Earth-Jupiter distance in 1 hour.
- Day 242 - At this speed (177500 km/s), ACEP would cover the Earth-Saturn distance in 2 hours.
- Day 245 - ACEP attained 60% of light speed
- Day 269 - At this speed (192200 km/s), ACEP would cover the Earth-Moon distance in 2 seconds.
- Day 307 - ACEP attained 70% of light speed
- Day 353 - At this speed (227700 km/s), ACEP would cover the Earth-Venus distance in 3 minutes.
- Day 389 - ACEP attained 80% of light speed
- Day 396 - At this speed (241700 km/s), ACEP would cover the Earth-Neptune distance in 5 hours.
- Day 433 - At this speed (252000 km/s), ACEP would cover the Earth-Uranus distance in 3 hours.
- Day 451 - At this speed (257000 km/s), ACEP would cover the Earth-Mercury distance in 5 minutes.
- Day 468 - At this speed (260000 km/s), ACEP would cover the Earth-Mars distance in 5 minutes.
- Day 521 - ACEP attained 90% of light speed
- Day 644 - Midpoint Achieved (peak velocity 94.89% of light speed)
Speed 0 equals LEO velocity at 200 km altitude
Distance Achievements
- Hour 1 - Covered a distance equivalent to Earth's circumference, distance travelled 0.04 mln km
- Hour 3 - Covered the distance of 0.38 mln km equal to the average Earth - Moon distance
- Hour 26 - Covered the distance of 41 mln km equal to the average Earth - Venus distance
- Hour 36 - Covered the distance of 78 mln km equal to the average Earth - Mars distance
- Hour 38 - Covered the distance of 91 mln km equal to the average Earth - Mercury distance
- Hour 49 - Covered the distance of 149 mln km equal to the average Earth - Sun distance (1 AU)
- Day 5 - Covered the distance of 628 mln km equal to the average Earth - Jupiter distance
- Day 6 - Covered the distance of 1275 mln km equal to the average Earth - Saturn distance
- Day 9 - Covered the distance of 2724 mln km equal to the average Earth - Uranus distance
- Day 11 - Covered the distance of 4351 mln km equal to the average Earth - Neptune distance
- Day 13 - Covered the distance of 5906 mln km equal to the average Earth - Pluto distance
- Day 15 - Covered the distance of 7800 mln km equal to the distance from Earth to New Horizons probe
- Day 17 - Covered the distance of 10500 mln km equal to the distance from Earth to Pioneer 11 probe
- Day 19 - Covered the distance of 12000 mln km equal to the distance from Earth to Pioneer 10 probe
- Day 24 - Covered the distance of 19600 mln km equal to the distance from Earth to Voyager 2 probe
- Day 26 - Covered the distance of 24000 mln km equal to the distance from Earth to Voyager 1 probe
Time Milestones
- Hour 3 - Communication delay exceeded 1 second
- Hour 4 - Velocity 127 km/s, 10000-year arrival if constant speed
- Hour 37 - Velocity 1271 km/s, 1000-year arrival if constant speed
- Day 9 - Time difference between ship and Earth exceeded 1 minute
- Day 16 - Velocity 12711 km/s, 100-year arrival if constant speed
- Day 17 - Velocity 14122 km/s, 90-year arrival if constant speed
- Day 19 - Velocity 15892 km/s, 80-year arrival if constant speed
- Day 22 - Velocity 18160 km/s, 70-year arrival if constant speed
- Day 25 - Velocity 21177 km/s, 60-year arrival if constant speed
- Day 30 - Estimated 50-Year arrival if speed remains constant
- Day 32 - Ship-Earth time difference exceeded 1 hour
- Day 38 - Velocity 31743 km/s, 40-year arrival if constant speed
- Day 51 - Velocity 42278 km/s, 30-year arrival if constant speed
- Day 72 - Velocity 63231 km/s, 20-year arrival if constant speed
- Day 91 - Ship-Earth time difference exceeded 1 day
- Day 134 - Velocity 124246 km/s, 10-year arrival if constant speed
- Day 156 - Velocity 137216 km/s, 9-year arrival if constant speed
- Day 199 - Velocity 152990 km/s, 8-year arrival if constant speed
- Day 232 - Velocity 172379 km/s, 7-year arrival if constant speed
- Day 277 - Velocity 196239 km/s, 6-year arrival if constant speed
- Day 322 - Nominal abort threshold crossed (2.7-year return)
- Day 323 - Final emergency abort threshold (7.5-year return)
- Day 344 - Velocity 224619 km/s, 5-year arrival if constant speed
- Day 441 - Velocity 253878 km/s, 4-year arrival if constant speed
- Day 560 - Velocity 275420 km/s, 3-year arrival if constant speed
- Day 618 - Ship-Earth time difference exceeded 1 year
- Day 865 - Ship-Earth time difference exceeded 2 years
