New Frontiers program

Pluto viewed by the spacecraft New Horizons on July 14, 2015

Pluto's moon Charon on July 14, 2015, imaged by "New Horizons"

New Horizons, a mission to Pluto, was launched on January 19, 2006. After a Jupiter gravity assist in February 2007 the spacecraft continued towards Pluto. The primary mission flyby occurred on July 14, 2015, and the spacecraft was then targeted toward one Kuiper Belt object called 486958 Arrokoth for a January 1, 2019 flyby.[9][10] Another mission that was considered with this mission was New Horizons 2.[11]

Artists's concept of Juno at Jupiter

Juno is a Jupiter exploration mission which launched on August 5, 2011, and arrived in July 2016. It is the first solar-powered spacecraft to explore an outer planet. The craft was placed into a polar orbit in order to study the planet's magnetic field and internal structure. NASA's Galileo mission to Jupiter provided extensive knowledge about its upper atmosphere, however, further study of Jupiter is crucial not only to the understanding of its origin and nature of the Solar System, but also of giant extrasolar planets in general. The Juno spacecraft investigation is intended to address the following objectives for Jupiter:

• Understand Jupiter's gross dynamical and structural properties through determination of the mass and size of Jupiter's core, its gravitational and magnetic fields, and internal convection;
• Measure the Jovian atmospheric composition, particularly the condensable-gas abundances (H₂O, NH₃, CH₄ and H₂S), the Jovian atmospheric temperature profile, wind velocity profile, and cloud opacity to greater depths than achieved by the Galileo entry probe with a goal of 100 bar at multiple latitudes; and
• Investigate and characterize the three-dimensional structure of Jupiter's polar magnetosphere.

Mission logo

OSIRIS-REx stands for "Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer", and was launched on 8 September 2016.[12] This mission plan was to orbit an asteroid, at the time named 1999 RQ₃₆ (now 101955 Bennu), by 2020. After extensive measurements, the spacecraft collected a sample from the asteroid's surface for return to Earth in 2023. The mission, minus the cost of the launch vehicle ($183.5 million), is expected to cost approximately $800 million.[13][14] The returned sample will help scientists answer long-held questions about the formation of the Solar System and the origin of complex organic molecules necessary for the origin of life.[15][16]

Asteroid Bennu is a potential future Earth impactor and is listed on the Sentry Risk Table with the third highest rating on the Palermo Technical Impact Hazard Scale (circa 2015).[17] In the late 2100s there is a cumulative chance of about 0.07% it could strike Earth, therefore there is a need to measure the composition and Yarkovsky effect of the asteroid.[18]

Artists concept of Dragonfly landing on Titan

Dragonfly Mission Insignia

Dragonfly will send a mobile robotic rotorcraft to Saturn's biggest moon Titan[19] and will make use of Multi-Mission Radioisotope Thermoelectric Generators (MMRTG) for power to navigate through the atmosphere of Titan.[3][20][21] The development cost cap is approximately $1 billion.[22] As of May 2021, Dragonfly is scheduled for launch in June 2027.[23][24]

The competition for the fourth mission began in January 2017. Per recommendation by the Decadal Survey, NASA's announcement of opportunity was limited to six mission themes:[22]

1. Comet Surface Sample Return - a comet nucleus lander and sample return mission
2. Lunar South Pole Sample Return - a mission to land at the Moon's South Pole–Aitken basin and return samples to Earth
3. Ocean Worlds (Titan and/or Enceladus)
4. Saturn Probe - an atmospheric probe
5. Trojan Tour and Rendezvous - a mission to fly by two or more Trojan asteroids
6. Venus Lander

NASA received and reviewed 12 proposals:[22][25]

Comet Surface Sample Return

• Comet Nucleus Dust and Organics Return (CONDOR), to retrieve a sample from 67P/Churyumov–Gerasimenko.[25][26]
• Comet Rendezvous, Sample Acquisition, Investigation, and Return (CORSAIR) would sample comet 88P/Howell.[25][27]
• Comet Astrobiology Exploration Sample Return (CAESAR) to comet 67P/Churyumov–Gerasimenko[28]

Lunar South Pole Sample Return

• MoonRise, a sample return mission to explore the lunar South Pole–Aitken basin[25]

Ocean Worlds

• Oceanus, an orbiter to investigate Titan's potential habitability.[29]
• Dragonfly, a rotorcraft that would fly over the landscape and oceans of Titan to study prebiotic chemistry.[19][30]
• Enceladus Life Finder (ELF), an astrobiology orbiter to Enceladus.[31][32][33]
• Enceladus Life Signatures and Habitability (ELSAH)[25][34]

Saturn Probe

• Saturn PRobe Interior and aTmosphere Explorer (SPRITE), an atmospheric probe to investigate Saturn's atmosphere and composition.[35]

Trojan Tour and Rendezvous

• None[note 1]

Venus Lander

• Venus In Situ Atmospheric and Geochemical Explorer (VISAGE), a Venus atmospheric probe and lander.[36]
• Venus In situ Composition Investigations (VICI), a lander.[25][37]
• Venus Origins Explorer (VOX), a Venus orbiter.[38]

Out of 12 initial proposals, NASA selected two for additional concept studies on 20 December 2017, including Dragonfly.[39]

The two finalists, CAESAR and Dragonfly, each received $4 million funding through the end of 2018 to further develop and mature their concepts.[40] On June 27, 2019, NASA announced the selection of Dragonfly as the New Frontiers 4 mission for a launch in 2026,[41] later delayed to June 2027.[23][24]

The Decadal Survey recommends that two New Frontiers missions be selected per decade. The 2018 Midterm Review of the 2013–2022 Decadal Survey found that NASA was falling behind on this cadence, and recommended the release of the New Frontiers 5 Announcement of Opportunity no later than December 2021.[42] Thomas Zurbuchen, Associate Administrator for the Science Mission Directorate, responded positively to the Midterm Review's recommendation, stating that NASA was "committed to conducting two New Frontiers competitions per decade" and planned to release the Announcement of Opportunity in 2021 or 2022,[43] though the Midterm Review estimated a release date as late as 2023.[42]

The Decadal Survey recommended the Io Observer and Lunar Geophysical Network proposals for New Frontiers 5, in addition to the previous recommendations.[44]

NASA released the draft of the Announcement of Opportunity New Frontiers 5 on January 10, 2023.[45] On August 24, 2023, NASA announced that due to budgetary constraints enacted through the Fiscal Responsibility Act of 2023, the official release of the Announcement of Opportunity for New Frontiers 5 would be delayed to no earlier than 2026.[46]