Mission record
Mariner 10
Also known as Mariner '73, Mariner-J, PL-732A, Mariner Venus/Mercury 73, Mariner10
NASA-Office of Space Science Applications · Launched
Explore trajectoryCompleted · Success
NASA Mariner-series spacecraft that flew past Venus once and Mercury three times between February 1974 and March 1975 and returned the first close-up images of both planets. NSSDCA records it as the first spacecraft to visit Mercury, the first to use the gravitational pull of one planet to reach another, and the first spacecraft mission to visit two planets. Engineering tests continued until 24 March 1975, when the supply of attitude-control gas was depleted and the mission was terminated.
- Launch vehicle
- Atlas-Centaur
- Launch site
- Cape Canaveral, United States
- Countries
- United States
- Mission types
- Flyby
Chronology
Mission timeline
Launch
Launch on an Atlas-Centaur from Cape Canaveral
NSSDCA's launch/orbital information page gives the launch date and time as 1973-11-03T05:45:00Z. The spacecraft was placed in a parking orbit for approximately 25 minutes, then placed in orbit around the Sun en route to Venus. Recorded at minute precision because the page prints a whole minute with zero seconds. The NSSDCA Chronology of Lunar and Planetary Exploration dates this launch to 4 November 1973 while the master catalog prints 1973-11-03 and GCAT prints 1973 Nov 3; the record follows the two that agree and the disagreement is recorded rather than resolved.
EarthMilestone
Trajectory correction
The NASA history records this course correction. A direction-resolved actual burn vector was not acquired; no constant-velocity coast is assumed across it.
SunMilestone
Trajectory correction
The NASA history records this course correction. A direction-resolved actual burn vector was not acquired; no constant-velocity coast is assumed across it.
SunGravity assist
Venus gravity-assist flyby
The spacecraft passed Venus on 05 February 1974, at a closest range of 5768 km at 17:01 UT, and returned the first close-up images of Venus. NSSDCA describes this as the first time a spacecraft used a gravity assist from one planet to help it reach another, and its launch/orbital information page gives the periapsis as 1.96 Venus radii (1 RV = 6052 km).
VenusMilestone
Trajectory correction
The NASA history records this course correction. A direction-resolved actual burn vector was not acquired; no constant-velocity coast is assumed across it.
SunFlyby
First Mercury flyby
Mariner 10 crossed the orbit of Mercury on 29 March 1974, at 20:46 UT, at a distance of about 704 km from the surface. NSSDCA's launch/orbital information page gives the closest approach time as 1974-03-29 20:46:38 UTC and the periapsis as 1.29 Mercurian radii (1 RH = 2,439 km).
MercuryMilestone
Trajectory correction
The NASA history records this course correction. A direction-resolved actual burn vector was not acquired; no constant-velocity coast is assumed across it.
SunMilestone
Trajectory correction
The NASA history records this course correction. A direction-resolved actual burn vector was not acquired; no constant-velocity coast is assumed across it.
SunMilestone
Trajectory correction
The NASA history records this course correction. A direction-resolved actual burn vector was not acquired; no constant-velocity coast is assumed across it.
SunFlyby
Second Mercury flyby
A second encounter with Mercury, when more photographs were taken, occurred on 21 September 1974, at an altitude of 48,069 km. The lighted hemisphere was almost the same as at the first encounter, so a large portion of the planet remained unimaged. Closest approach 1974-09-21 21:59:00 UTC, periapsis 20.27 Mercurian radii. NSSDCA's two pages do not reconcile on this encounter, and the disagreement is recorded rather than resolved: at the launch/orbital page's own definition of 1 RH = 2,439 km, a periapsis of 20.27 RH places closest approach about a thousand kilometres below the altitude of 48,069 km the master catalog prints. The first and third Mercury encounters reconcile between the same two pages; this one does not, and no figure here is adjusted for it. NASA history instead gives20:59UT. The existing21:59 clock is retained pending original flight-report resolution; this disagreement is not used to extend the first-flyby SPK.
MercuryMilestone
Trajectory correction
The NASA history records this course correction. A direction-resolved actual burn vector was not acquired; no constant-velocity coast is assumed across it.
SunMilestone
Trajectory correction
The NASA history records this course correction. A direction-resolved actual burn vector was not acquired; no constant-velocity coast is assumed across it.
SunMilestone
Trajectory correction
The NASA history records this course correction. A direction-resolved actual burn vector was not acquired; no constant-velocity coast is assumed across it.
SunFlyby
Third Mercury flyby
A third and last Mercury encounter at an altitude of 327 km, with additional photography of about 300 frames and magnetic field measurements, occurred on 16 March 1975. Closest approach 1975-03-16 22:39:23 UTC, periapsis 1.13 Mercurian radii.
MercuryMission end
Final contact after attitude-gas exhaustion
NASA chronology reports final contact at12:21UT onMarch24. No later measured attitude or navigation is inferred.
Sun
Mission architecture
Vehicles
Trajectory record
Time-dependent navigation trajectory
Source states place the model at the selected time. Reconstructed flight, estimates, predictions and historical mission plans are identified by interval; gaps remain visible.
Source records and sampling assumptions are retained with the repository data. Model attitude and surface appearance are illustrative.
- Mariner 10: Estimated · March 21, 1974 to April 4, 1974
Provenance
Sources
Each source is listed once and labeled with the mission, event, trajectory, or destination/body context it supports.
Data verified through September 14, 2026
- Mariner 10 - NSSDCA Master Catalog (spacecraft 1973-085A), archived snapshot — NSSDCAArchive · Supports: mission claims · event claims
- Mariner 10 - NSSDCA launch/orbital information (1973-085A), archived snapshot — NSSDCAArchive · Supports: mission claims · event claims
- Chronology of Lunar and Planetary Exploration - NASA NSSDCA — NSSDCAArchive · Supports: mission claims · event claims
- GCAT: General Catalog of Artificial Space Objects (heliocentric catalog), J. McDowell — OTHEROther · Supports: mission claims · event claims
- Mariner 10: spacecraft and original data products reviewed September2026 — NSSDCAMission page · Supports: mission claims · event claims
- Siddiqi (2018): Beyond Earth, a chronicle of deep space exploration 1958–2016 — NASAMission page · Supports: mission claims · event claims
- Historical Mariner 10 SPICE coverage and quality statement — NAIFSpice · Supports: mission claims · event claims
- Mariner10 first Mercury flyby original position tables — NASAArchive · Supports: mission claims · event claims
- Mariner10 third Mercury flyby original42-second position tables — NASAArchive · Supports: mission claims · event claims
- Planet Sizes and Locations in Our Solar System — NASAOther · Supports: destination/body context
- Our Sun: Facts — NASAOther · Supports: destination/body context