Mariner 10

Chronology

Mission timeline

1. November 3, 1973, 05:45 UTC

   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.

   Earth
2. February 5, 1974, 17:01 UTC

   Gravity 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).

   Venus
3. March 29, 1974, 20:46:38 UTC

   Flyby

   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).

   Mercury
4. September 21, 1974, 21:59 UTC

   Flyby

   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.

   Mercury
5. March 16, 1975, 22:39:23 UTC

   Flyby

   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.

   Mercury
6. March 24, 1975

   Mission end

   Mission terminated

   Engineering tests were continued until 24 March 1975, when the supply of attitude-control gas was depleted and the mission was terminated.

Mission architecture

Vehicles

• Mariner 10 · Spacecraft · Terminated on 24 March 1975 when the supply of attitude-control gas was depleted

  Destinations: Mercury, Venus