TheTerrestrial Planet Finder (TPF) was a proposed project byNASA to construct a system ofspace telescopes fordetectingextrasolarterrestrial planets. TPF was postponed several times and finally cancelled in 2011.^[1][2] There were two telescope systems under consideration, theTPF-I, which had several small telescopes, andTPF-C, which used one large telescope.

In May 2002, NASA chose two TPF mission architecture concepts for further study and technology development. Each would use a different means to achieve the same goal—to block the light from a parentstar in order to see its much smaller, dimmer planets. The technological challenge of imaging planets near their much brighter star has been likened to finding afirefly near the beam of a distantsearchlight. Additional goals of the mission would include the characterization of the surfaces andatmospheres of newfound planets, and looking for the chemical signatures of life.

The two planned architectures were:

• Infraredastronomical interferometer (TPF-I): Multiple small telescopes on a fixed structure or on separated spacecraft floating in precision formation would simulate a much larger, very powerful telescope. The interferometer would use a technique callednulling to reduce the starlight by a factor of one million, thus enabling the detection of the very dim infrared emission from the planets.
• Visible LightCoronagraph (TPF-C): A large optical telescope, with a mirror three to four times bigger and at least 100 times more precise than theHubble Space Telescope, would collect starlight and the very dim reflected light from the planets. The telescope would have special optics to reduce the starlight by a factor of one billion, thus enabling astronomers to detect faint planets.

NASA andJet Propulsion Laboratory (JPL) were to issue calls for proposals seeking input on the development and demonstration of technologies to implement the two architectures, and on scientific research relevant to planet finding. Launch of TPF-C had been anticipated to occur around 2014, and TPF-I possibly by 2020.

According to NASA's 2007 budget documentation, released on February 6, 2006,^[3] the project was deferred indefinitely.^[4]

In June 2006, aHouse of Representatives subcommittee voted to provide funding for the TPF along with the long-sought mission toEuropa, a moon of Jupiter that might harborextraterrestrial life.^[5] Congressional spending limits under House Resolution 20 passed on January 31, 2007, by theUnited States House of Representatives and February 14 by theU.S. Senate postponed the program indefinitely. Actual funding has not materialized, and TPF remains a concept.^[6] In June 2011, the TPF (andSIM) programs were reported as "cancelled".^[1]

• Automated Planet Finder – Robotic optical telescope searching for extrasolar planets
• CoRoT – European space telescope that operated between 2006 - 2014
• Darwin – 2007 European study concept of an array of space observatories
• High Accuracy Radial Velocity Planet Searcher – Instrument for detecting planets
• James Webb Space Telescope – NASA/ESA/CSA space telescope launched in 2021
• Kepler space telescope – NASA space telescope for exoplanetology (2009–2018)
• List of NASA cancellations
• Navigator Program
• Space Interferometry Mission – Cancelled NASA space telescope

Wikimedia Commons has media related toTerrestrial Planet Finder.

• Canceling NASA's Terrestrial Planet Finder: The White House's Increasingly Nearsighted "Vision" For Space Exploration
• Congressional Inaction Leaves Science Still Devastated. Planetary Society (2006-11-26).
• Current status of TPF development work (March 2007)
• Interferometric Nulling at TNO
• Planet Imager (PI)

• Cancelled spacecraft
• Space telescopes
• Exoplanet search projects
• Astronomy projects
• Cancelled astrobiology space missions
• Projects disestablished in 2011

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