Discovery Program

2016 InSight Mars lander

NASA's Discovery Program (as compared to New Frontiers, Explorer, or Flagship Programs) is a series of lower-cost, highly focused American scientific space missions that are exploring the Solar System. It was founded in 1992 to implement then-NASA Administrator Daniel S. Goldin's vision of "faster, better, cheaper" planetary missions. Discovery missions differ from traditional NASA missions where targets and objectives are pre-specified. Instead, these cost-capped missions are proposed and led by a scientist called the Principal Investigator (PI). Proposing teams may include people from industry, small businesses, government laboratories, and universities. Proposals are selected through a competitive peer review process. All of the completed Discovery missions are accomplishing ground-breaking science and adding significantly to the body of knowledge about the Solar System.

NASA also accepts proposals for competitively selected Discovery Program Missions of Opportunity. This provides opportunities to participate in non-NASA missions by providing funding for a science instrument or hardware components of a science instrument or to re-purpose an existing NASA spacecraft. These opportunities are currently offered through NASA's Stand Alone Mission of Opportunity program.

History

In 1989, the Solar System Exploration Division (SSED) at NASA Headquarters initiated a series of workshops to define a new strategy for exploration through the year 2000. The panels included a Small Mission Program Group (SMPG) that was chartered to devise a rationale for missions that would be low cost and allow focused scientific questions to be addressed in a relatively short time.^[1] A fast-paced study for a potential mission was requested and funding arrangements were made in 1990. The new program was called 'Discovery' and the panel assessed a number of concepts that could be implemented as low-cost programs, with 'Near Earth Asteroid Rendezvous' (NEAR) as the first mission to be implemented.^[1] On February 17, 1996, NEAR became the first mission to launch in the Discovery Program.^[1] The Mars Pathfinder launched on December 4, 1996, demonstrated a number of innovative, economical, and highly effective approaches to spacecraft and planetary mission design such as the inflated air bags that allowed the Sojourner rover endure the landing.^[1]

Standalone missions

Asteroid 253 Mathilde

Mars Pathfinder's view

Animation of the rotation of 433 Eros.

• Mars Pathfinder (Mission #1), a Mars lander to deploy Sojourner rover on the surface. Launched in 1996, it landed on Mars on July 4, 1997. It has completed its primary and extended mission. The Principal Investigator was Matthew Golombek of NASA’s Jet Propulsion Laboratory.

• NEAR Shoemaker (Mission #2), a mission to study asteroid 433 Eros. Launched in 17 February 1996, the spacecraft entered into orbit around Eros in 2000 and successfully touched down on its surface one year later. It has succeeded its primary and extended mission and is now complete. The Project Scientist was Andrew Chang of The Johns Hopkins University Applied Physics Laboratory.

• Lunar Prospector (Mission #3), a Moon orbiter to characterize the lunar mineralogy. Launched in 1998, it spent 1½ years in lunar orbit. It has completed its primary and extended mission and deliberately impacted onto the Moon's surface. The Principal Investigator was Alan Binder of the Lunar Research Institute.

• Stardust (Mission #4), a mission to collect interstellar dust and dust particles from the nucleus of comet 81P/Wild for study on Earth. Launched in 1999, it successfully collected samples between 2000–2004, then the sample return capsule returned to Earth on Jan. 15, 2006. The capsule is on display at the National Air and Space Museum in Washington D.C. Scientists worldwide are studying the comet dust samples while citizen scientists are finding interstellar dust bits through the Stardust@home project. The spacecraft has been assigned a new task, called Stardust-NExT. The Principal Investigator was Donald Brownlee of the University of Washington.

• Genesis (Mission #5), a mission to collect solar wind charged particles for analysis on Earth. Launched in 2001, it collected solar wind between 2002–2003. In Sept. 2004, the sample return capsule's parachute failed to deploy, and the capsule crashed into the Utah desert. However, solar wind samples were salvaged and are available for study. Despite the hard landing, Genesis has met or anticipates meeting all its baseline science objectives. The Principal Investigator was Donald Burnett of the California Institute of Technology.

• Comet Nucleus Tour (CONTOUR) (Mission #6), was a failed mission to visit and study comets Encke and Schwassmann-Wachmann-3. It was launched on July 3, 2002. Six weeks after launch, after a planned maneuver that was intended to propel it out of Earth orbit and into its comet-chasing solar orbit, the spacecraft was lost. The investigation board concluded the probable cause was structural failure of the spacecraft due to plume heating during the embedded solid-rocket motor burn.^[1][2] Subsequent investigation revealed that it broke into at least three pieces, the cause likely being structural failure during the rocket motor burn that was to push it from Earth orbit into a solar orbit.

MESSENGER imaging Mercury's surface hollows at Sholem Aleichem.^[3]

• MESSENGER (Mission #7) (Mercury Surface, Space Environment, Geochemistry and Ranging) conducted the first orbital study of Mercury. MESSENGER's science goals were to provide the first images of the entire planet and collect detailed information on the composition and structure of Mercury's crust, its geologic history, the nature of its thin atmosphere and active magnetosphere, and the makeup of its core and polar materials. It was launched on August 3, 2004 and entered orbit around Mercury on March 18, 2011. The primary mission was completed on March 17, 2012. It achieved 100% mapping of Mercury on March 6, 2013, and completed its first year-long extended mission on March 17, 2013. The mission had two more extensions until the spacecraft ran out of propellant and was deorbited on 30 April 2015.^[4]
• Deep Impact (Mission #8), a mission in which a spacecraft released an impactor into the path of comet Tempel 1. Launched in January 2005, the impact occurred on July 4, 2005. After the successful completion of its mission, it was put in hibernation and then reactivated for a new mission designated EPOXI. The Principal Investigator was Michael A'Hearn of the University of Maryland.
• Dawn (Mission #9) was launched on 27 September 2007 to study the two most massive objects of the asteroid belt – the protoplanet Vesta and the dwarf planet Ceres. It completed the study of Vesta on September 2012 and is currently orbiting Ceres, where it arrived in March 2015.^[5][6] It is using solar electric ion thrusters to orbit both asteroids in one mission, a feat that has not been attempted before.

Kepler's image sensor array.

• Kepler (Mission # 10) is a space observatory tasked to explore the structure and diversity of exoplanet systems, with a special emphasis on the detection of Earth-size planets in orbit around stars outside our Solar System.^[7] The spacecraft was launched on March 7, 2009.^[8]
• Gravity Recovery and Interior Laboratory, (GRAIL) (Mission #11) provided higher-quality gravity field mapping of the Moon to determine its interior structure; launched in September 2011.^[9] The Principal Investigator is Maria Zuber of the Massachusetts Institute of Technology. GRAIL spacecraft impacted the Moon on December 17, 2012.

Missions of opportunity

This provides opportunities to participate in non-NASA missions by providing funding for a science instrument or hardware components of a science instrument.

• Moon Mineralogy Mapper is a NASA-designed instrument placed on board the ISRO's Chandrayaan orbiter. Launched in 2008, it was designed to explore the Moon's mineral composition at high resolution. M3’s detection of water on the Moon was announced in Sept. 2009, one month after the mission ended. The Principal Investigator was Dr. Carle Pieters of Brown University.
• Extrasolar Planet Observation and Deep Impact Extended Investigation (EPOXI) was selected in 2007.^[10] It was a series of two new missions for the existing Deep Impact probe following its success at Tempel 1:
• The Extrasolar Planet Observations and Characterization (EPOCh) mission used the Deep Impact high-resolution camera in 2008 to better characterize known giant extrasolar planets orbiting other stars and to search for additional planets in the same system. The Principal Investigator was Dr. L. Drake Deming of NASA's Goddard Space Flight Center.

Nucleus of Comet Hartley 2

• The Deep Impact eXtended Investigation of Comets (DIXI) mission used the spacecraft for a flyby mission to a second comet, Hartley 2. The goal was to take pictures of its nucleus to increase our understanding of the diversity of comets. The flyby of Hartley 2 was successful with closest approach occurring on Nov. 4, 2010. Dr. Michael A'Hearn of the University of Maryland was the Principal Investigator.
• New Exploration of Tempel 1 (NExT) was a new mission for the Stardust spacecraft to fly by comet Tempel 1 in 2011 and observe changes since the Deep Impact mission visited it in July 2005. Later in 2005, Tempel 1 made its closest approach to the Sun, possibly changing the surface of the comet. The flyby was completed successfully on Feb. 15, 2011. Dr. Joseph Veverka of Cornell University is the Principal Investigator.

Examples of proposals

However often the funding comes in, there is a selection process with perhaps 2 dozen concepts. These sometimes get further matured and re-proposed in another selection or program.^[11] An example of this is Suess-Urey Mission, which was passed over in favor of the successful Stardust mission, but was eventually flown as Genesis,^[11] while a more extensive mission similar to INSIDE was flown as Juno in the New Frontiers program. Some of these concepts went on to become actual missions, or similar concepts were eventually realized in another other mission class. This list is a mix of previous and current proposals.

The Venus Multiprobe Mission involved sending 16 atmospheric probes into Venus in 1999.^[12]

Additional examples of Discovery-class mission proposals include:

• Titan Mare Explorer (TiME) spacecraft for landing in, and floating on, a large methane-ethane sea on Saturn's moon Titan.
• Comet Hopper (CHopper) study cometary evolution by landing on a comet multiple times and observing its changes as it interacts with the Sun.
• Io Volcano Observer
• Pascal, a Mars climate network mission.^[13]
• EXOMOON, in situ investigation on Earth's Moon.^[14]
• PSOLHO, would use the Moon as an occulter to look for exoplanets.^[15]
• Suess-Urey, similar to the later Genesis mission.^[11]
• Venus Multiprobe, proposed for a 1999 launch, would have dropped 16 atmospheric probes into Venus, and fall slowly to the surface, making pressure and temperature measurements.^[11]
• MAUDEEE (Mars Upper Atmosphere Dynamics, Energetics, and Evolution)^[16]
• Hermes, a Mercury orbiter.^[17]
• Lunette, a lunar lander.^[18]
• INSIDE Jupiter, an orbiter that would map Jupiter's magnetic and gravity fields in an effort to study the giant planet's interior structure.^[19] The concept was further matured and implemented as Juno in the New Frontiers program.^[20]
• Vesper was a concept for a Venus orbiter focused on studying that planet's atmosphere.^[21][22][23] It was one of three concepts to receive funds for further study in the 2006 Discovery selection.^[22] Osiris and GRAIL were the other two, and eventually GRAIL was chosen and went on to be launched.^[24]
• OSIRIS (Origins Spectral Interpretation, Resource Identification and Security) was an asteroid observation and sample return mission concept selected in 2006 for further concept studies.^[24] It was further matured and will be launched in September 2016 as OSIRIS-REx in the New Frontiers Program.^[25]
• Aladdin was a discovery-class Phobos and Deimos sample return mission.^[26] It was a finalist in the 1999 Discovery selection, with a planned launch in 2001 and return of the samples by 2006.^[27] Sample collection was intended to work by sending projectiles into the moons, then collecting the ejecta.^[27]
• 16 Psyche, a mission to a metal asteroid.^[28]
• The Dust Telescope is a space observatory that would measure various properties of incoming cosmic dust.^[29] The dust telescope would combine a trajectory sensor and a mass spectrometer, to allow the elemental and even isotopic composition to be analyzed.^[29]
• Phobos Surveyor is an orbiter mission concept to the Mars moon Phobos, which would also deploy special rovers for the Moon's low gravity environment.
• PCROSS, based on LCROSS but to Mars' moon Phobos.^[30]
• Merlin mission would place a lander on Mars' moon Deimos.^[31]
• Mars Moons Multiple Landings Mission (M4), would conduct multiple landings on Phobos and Deimos.^[32]
• Hall is a Phobos and Deimos sample return mission.^[33]
• Hera is a mission concept for near-Earth asteroid sample return.^[34] Envisioned as the follow-on from the NEAR mission, the design was intended to collect three samples from three different asteroids.^[35]

• VEVA (Venus Exploration of Volcanoes and Atmosphere) is an in atmosphere probe for Venus.^[36] The centerpiece is a 7-day balloon flight through the atmosphere accompanied by various tiny probes dropped deeper into the planet's thick gases.^[36]
• Venus Pathfinder, a long-duration Venus lander.^[37]
• RAVEN, a Venus orbiter radar mapping mission.^[38]
• VALOR, a Venus mission to study its atmosphere with a balloon.^[39] Twin balloons would circumnavigate the planet over 8 Earth-days.^[39]

Mars Geyser Hopper would investigate 'spider' features on Mars, as imaged by an orbiter. Image size: 1 km (0.62 mi) across.

• Mars Geyser Hopper is a lander that would investigate the springtime carbon dioxide Martian geysers found in regions around the south pole of Mars.^[40][41][42]
• MAGIC (Mars Geoscience Imaging at Centimeter-scale) is an orbiter that would provide images of the Martian surface at 5–10 cm/pixel, permitting resolution of features as small as 20–40 cm.^[43]
• Venus Aircraft, a robotic atmospheric flight on Venus' atmosphere using a long-duration solar-powered aircraft system.^[44] It would carry 1.5 kg of scientific payload and it must contend with violent wind, heat and a corrosive atmosphere.^[44]
• Red Dragon, a Mars lander and sample return.^[45]
• Small Body Grand Tour, an asteroid rendezvous mission.^[46]
• Comet Coma Rendezvous Sample Return, a spacecraft designed to rendezvous with a comet, make extended observations within the cometary coma (but not land on the comet), gently collect multiple coma samples, and return them to Earth for study.^[47]
• Twin Lunar Lander, a geophysics mission to the Moon.^[48]
• Micro Exo Explorer would use a new form of micro-electric propulsion, called 'Micro Electro-fluidic-spray Propulsion' to travel to a near Earth object and gather important data.^[49]
• V-STAR (Venus Sample Targeting, Attainment and Return) is a Venus atmosphere sample return mission.^[50][51] While returning samples from the surface of Venus has noted difficulties, a discovery-class sample return from the upper atmosphere is being proposed.^[50] Something along the lines of Stardust mission but using a free-return trajectory (it would not go into Venusian orbit).^[50]

Possible configuration of a lunar sample return spacecraft

• Lunar sample return from the South Pole–Aitken basin. No geologic model adequately accounts for all of the characteristics of the area and disagreements are fundamental.^[52]
• Lunar Lander.- Since Discovery missions are permitted to have international co-operation,^[53] there is the option to partner with Germany on its currently halted 'Lunar Lander' mission; Germany was willing to contribute up to 45% of the mission's total cost.^[54] The total cost (including a 6 month-long mission at the lunar south pole) was estimated at 500 million euros (about US$640 million).^[55] Spain also wanted to contribute to the total, but could not make up the shortfall.^[54]

Missions in progress

Standalone missions

• Dawn, a mission to study the dwarf planet Ceres and large asteroid Vesta; launched in September 2007. It reached Vesta in July 2011. Dawn uses ion propulsion, allowing both Ceres and Vesta to be orbited in one mission. The Principal Investigator is Chris Russell of the University of California, Los Angeles. It is currently in orbit around Ceres.
• Kepler, a space telescope mission that continuously observed 100,000 stars in a fixed field of view in order to detect transits by exoplanets orbiting those stars. It was launched in March 2009 and announced its first exoplanet discoveries in January 2010. Kepler is the first spacecraft capable of finding Earth-size planets around other stars. The Principal Investigator is William Borucki of NASA’s Ames Research Center. It is currently experiencing technical difficulties, but may have a follow on mission.

Missions of opportunity

• ASPERA-3, an instrument designed to study the interaction between the solar wind and the atmosphere of Mars, is flying on board the European Space Agency's Mars Express orbiter. Launched in June 2003, it has been orbiting Mars since Dec. 2003. The Principal Investigator is David Winningham of Southwest Research Institute.

Future missions

InSight Mars lander

InSight (Mission #12)– An Announcement of Opportunity for the 2016 Discovery mission was released by NASA on June 7, 2010. Twenty-eight proposals were submitted, and on May 5, 2011, three were chosen for further study.^[56] Following these one-year preliminary design studies, the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission was selected in August 2012. InSight (initially named Geophysical Monitoring Station or GEMS) will study the structure and composition of the interior of Mars and advance understanding of the formation and evolution of terrestrial planets.^[57] An Announcement of Opportunity for a Discovery mission was released by NASA on June 7, 2010. Out of 28 proposals from 2010,^[58] three finalists received US$3 million in May 2011 to develop a detailed concept studies.^[56] In August 2012, InSight was selected for development and launch.^[59] According to the BBC, of the 28 mission proposals, 3 were for the Moon, 4 for Mars, 7 for Venus, 1 Jupiter, 1 to a Jupiter Trojan, 2 to Saturn, 7 to asteroids, and 3 to Comets.^[60]

Missions of opportunity

This provides opportunities to participate in non-NASA missions by providing funding for a science instrument or hardware components of a science instrument.

• Strofio^[61] is a unique mass spectrometer that is part of the SERENA instrument package that will fly on board the European Space Agency's BepiColombo/Mercury Planetary Orbiter spacecraft. Strofio will study the atoms and molecules that compose Mercury's atmosphere to reveal the composition of the planet's surface. Stefano Livi of Southwest Research Institute is the Principal Investigator.

Discovery Mission 13

NASA is considering offering an ion thruster (solar electric propulsion) for the next Discovery class mission.^[62]

The Discovery Mission #13 has not been selected yet. In February 2014, NASA released a Discovery Program 'Draft Announcement of Opportunity' for launch readiness date of December 31, 2021.^[63] As with previous Discovery missions such as Dawn, solar electric propulsion may allow increased mission options if applicable.^[64] Technologies may include the NEXT ion thruster,^[65] laser communication,^[66] and/or re-entry technology.^[62] The main mission is budgeted for up to 450 million USD, with various conditions but also bonuses.^[53][62] For the first time, the $450 million cost cap will not include post-launch operations expenses.^[67] The candidate missions include among others:^[67]

• Binary Asteroid in-situ Explorer (BASiX)
• Comet Radar Explorer (CORE)
• Dark Asteroid Rendezvous (DARe)
• Enceladus Life Finder (ELF)
• Io Volcano Observer
• Journey to Enceladus and Titan (JET)^[68]
• Kuiper telescope
• Life Investigation For Enceladus (LIFE)
• Icebreaker Life would use the Phoenix/InSight platform but would carry a payload to search for past extraterrestrial life on Mars.^[69][70][71]
• Lucy — would tour Trojan asteroids^[72]
• Mars-Moons Exploration, Reconnaissance and Landed Investigation (MERLIN)
• Mission to 16 Psyche — the most massive metallic asteroid in the asteroid belt.
• Moon Age and Regolith Explorer
• NanoSWARM — CubeSat mission to study space weathering, lunar magnetism, lunar water and small-scale magnetospheres.
• Near-Earth Object Camera (NEOCam)
• Phobos And Deimos & Mars Environment (PADME)
• Phobos And Deimos Origin Assessment (PANDORA)
• Radar at Venus (RAVEN) - High-resolution Mapping of Venus^[73]
• Venus Atmosphere and Surface Explorer (VASE)
• Venus Emissivity, Radio Science, InSAR Topography and Spectroscopy (VERITAS)

In June 2015 NASA will announce a list of finalists for the current competition, followed by NASA's announcement of the final winner in September 2016. The selected mission must launch by the end of 2021.^[66][74]

Summary

Discovery Program
Deep Impact	Stardust	Genesis	GRAIL	Kepler Observatory	Dawn	MESSENGER
Lunar Prospector	Mars Pathfinder	NEAR	InSight

See also

• Explorer program
• Mars Scout Program
• New Frontiers Program
• New Millennium Program

References

External links

• Official NASA website for Discovery Program
• Official NASA website for Discovery & New Frontiers Programs Office

Discovery Program Completed CONTOUR (failed) Deep Impact/EPOXI Genesis GRAIL Lunar Prospector Mars Pathfinder MESSENGER Moon Mineralogy Mapper NEAR Shoemaker Stardust/NExT Active ASPERA-3 Dawn Kepler Planned InSight Concepts 16 Psyche Comet Hopper Enceladus Life Finder Io Volcano Observer Mars Geyser Hopper Near-Earth Object Camera PADME Titan Mare Explorer

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