Trident

Comparison of two designs forTrident
Mission type	Reconnaissance, flyby of outer planets
Operator	NASA
Mission duration	13 years (planned)
Start of mission
Launch date	Proposed: 25 October 2025 (with a backup in October 2026)[1]
Flyby ofEarth (gravity assist)
Closest approach	28 October 2026[2]
Flyby ofVenus (gravity assist)
Closest approach	25 March 2027[2]
Flyby of Earth (gravity assist)
Closest approach	7 February 2028[2]
Flyby of Earth (gravity assist)
Closest approach	7 February 2031[2]
Flyby ofJupiter,Io (gravity assist)
Closest approach	28 June 2032[2]
Distance	1.24RJ or 88,650 km (55,080 mi)
Flyby ofNeptune,Triton
Closest approach	28 June 2038[2]
Discovery Program ← Psyche

Trident is a space mission concept to theouter planets proposed in 2019 toNASA'sDiscovery Program.^[3][4] The concept includes flybys ofJupiter andNeptune with a focus on Neptune's largest moonTriton.

In 2020, Trident was selected along with three other Discovery proposals for further study, with two expected to be selected to fly asDiscovery 15 and 16.^[5] On 2 June 2021, NASA selected theVenus missionsDAVINCI+ andVERITAS over Trident and theIo Volcano Observer.^[6]

Triton is the largestmoon of Neptune. In 1989,Voyager 2 flew past the moon at a distance of 40,000 km (25,000 mi),^[7] and discovered severalcryovolcanoes on its surface. Triton is geologically active, its surface is young and has relatively few impact craters. It has a very thinatmosphere. Voyager 2 was only able to observe approximately 40% of Triton's surface.

TheTrident concept was proposed in March 2019 to NASA'sDiscovery Program. The mission concept is supported by NASA'sOcean Worlds Exploration Program and it is intended to help answer some of the questions generated byVoyager 2's flyby in 1989.^[8]

Trident takes advantage of an efficientgravity assist alignment of Jupiter and Neptune (that occurs once every 13 years) to capitalize on a narrow observational window that enables assessment of changes inTriton's plume activity and surface characteristics since the previous encounter of Neptune-Triton byVoyager 2 in 1989.^[3][9]

With the advances of high-resolution imaging and a unique orbital configuration of Triton in 2038,Trident would be able to obtain a near-complete map of Neptune's moon during its soleflyby.Trident would pass throughTriton's thin atmosphere, within 500 km (310 mi) of the surface, sampling its ionosphere with a plasma spectrometer and performmagnetic induction measurements to assess the potential existence of an internal ocean.^[3] The principal investigator isLouise Prockter, director of theLunar and Planetary Institute in Houston, Texas.^[9]

The launch vehicle proposed forTrident is theAtlas V 401, if it is not replaced with theVulcan.^[2]

The proposed launch date in October 2025 (with a backup in October 2026) would take advantage of a once-in-13-years window, when Earth is properly aligned with Jupiter. The spacecraft would use the gravitational pull of Jupiter as a slingshot straight to Triton for an extended 13-day encounter in 2038.^[1]

• 
  Venus (flyby)
• 
  Earth (3x flybys)
• 
  Jupiter (flyby)
• 
  Io (flyby)
• 
  Neptune (targeted flyby)
• 
  Triton (targeted flyby)

• Argo, a 2009 Triton flyby mission concept
• Interstellar Express, a Chinese probe proposed to fly by Neptune and Triton in January 2038 en route to the tail of the heliosphere
• New Horizons probe, performed a Pluto flyby in 2015
• New Horizons 2, a mission proposed in 2002 which might have included a Triton flyby
• Triton Hopper, a lander concept to Triton

• Discovery program proposals
• Proposed NASA space probes
• Missions to Neptune
• Triton (moon)
• Missions to Jupiter

• Source attribution
• Articles with short description
• Short description is different from Wikidata
• Use American English from July 2020
• All Wikipedia articles written in American English
• Use dmy dates from July 2020