The Terrestrial Planet Finder (TPF) was a proposed project by NASA to construct a system of space telescopes for detecting extrasolar terrestrial planets. TPF was postponed several times and finally cancelled in 2011. [1] [2] There were two telescope systems under consideration, the TPF-I, which had several small telescopes, and TPF-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 parent star 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 a firefly near the beam of a distant searchlight. Additional goals of the mission would include the characterization of the surfaces and atmospheres of newfound planets, and looking for the chemical signatures of life.
The two planned architectures were:
NASA and Jet 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 6 February 2006, [3] the project was deferred indefinitely. [4]
In June 2006, a House of Representatives subcommittee voted to provide funding for the TPF along with the long-sought mission to Europa, a moon of Jupiter that might harbor extraterrestrial life. [5] Congressional spending limits under House Resolution 20 passed on 31 January 2007, by the United States House of Representatives and 14 February by the U.S. Senate postponed the program indefinitely. Actual funding has not materialized, and TPF remains a concept. [6] In June 2011, the TPF (and SIM) programs were reported as "cancelled". [1]
| Rank [7] | Target star | Constellation | Distance (light-years) | Spectral type |
|---|---|---|---|---|
| 1 | Alpha Centauri A | Centaurus | 4.3 | G2V |
| 2 | Alpha Centauri B | Centaurus | 4.3 | K1V |
| 3 | Tau Ceti | Cetus | 12 | G8V |
| 4 | Eta Cassiopeiae | Cassiopeia | 19 | G3V |
| 5 | Beta Hydri | Hydrus | 24 | G2IV |
| 6 | Delta Pavonis | Pavo | 20 | G8V |
| 7 | Pi3 Orionis | Orion | 26 | F6V |
| 8 | Gamma Leporis | Lepus | 29 | F7V |
| 9 | Epsilon Eridani | Eridanus | 10 | K2V |
| 10 | 40 Eridani | Eridanus | 16 | K1V |
Infrared astronomy is a sub-discipline of astronomy which specializes in the observation and analysis of astronomical objects using infrared (IR) radiation. The wavelength of infrared light ranges from 0.75 to 300 micrometers, and falls in between visible radiation, which ranges from 380 to 750 nanometers, and submillimeter waves.
Planetshine is the dim illumination, by sunlight reflected from a planet, of all or part of the otherwise dark side of any moon orbiting the body. Planetlight is the diffuse reflection of sunlight from a planet, whose albedo can be measured.
The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003. Operations ended on 30 January 2020. Spitzer was the third space telescope dedicated to infrared astronomy, following IRAS (1983) and ISO (1995–1998). It was the first spacecraft to use an Earth-trailing orbit, later used by the Kepler planet-finder.
The Space Interferometry Mission, or SIM, also known as SIM Lite, was a planned space telescope proposed by the U.S. National Aeronautics and Space Administration (NASA), in conjunction with contractor Northrop Grumman. One of the main goals of the mission was the hunt for Earth-sized planets orbiting in the habitable zones of nearby stars other than the Sun. SIM was postponed several times and finally cancelled in 2010. In addition to detecting extrasolar planets, SIM would have helped astronomers construct a map of the Milky Way galaxy. Other important tasks would have included collecting data to help pinpoint stellar masses for specific types of stars, assisting in the determination of the spatial distribution of dark matter in the Milky Way and in the local group of galaxies and using the gravitational microlensing effect to measure the mass of stars. The spacecraft would have used optical interferometry to accomplish these and other scientific goals.
Darwin was a suggested ESA Cornerstone mission which would have involved a constellation of four to nine spacecraft designed to directly detect Earth-like planets orbiting nearby stars and search for evidence of life on these planets. The most recent design envisaged three free-flying space telescopes, each three to four metres in diameter, flying in formation as an astronomical interferometer. These telescopes were to redirect light from distant stars and planets to a fourth spacecraft, which would have contained the beam combiner, spectrometers, and cameras for the interferometer array, and which would have also acted as a communications hub. There was also an earlier design, called the "Robin Laurance configuration," which included six 1.5 metre telescopes, a beam combiner spacecraft, and a separate power and communications spacecraft.
The New Worlds Mission is a proposed project comprising a large occulter flying in formation with a space telescope designed to block the light of nearby stars in order to observe their orbiting exoplanets. The observations could be taken with an existing space telescope or a dedicated visible light optical telescope optimally designed for the task of finding exoplanets. A preliminary research project was funded from 2005 through 2008 by NASA Institute for Advanced Concepts (NIAC) and headed by Webster Cash of the University of Colorado at Boulder in conjunction with Ball Aerospace & Technologies Corp., Northrop Grumman, Southwest Research Institute and others. Since 2010 the project has been looking for additional financing from NASA and other sources in the amount of roughly US$3 billion including its own four-meter telescope. If financed and launched, it would operate for five years.
NASA's Origins program is a decades-long study addressing the origins of the universe, various astronomical bodies, and life. The Origins program was started in the 1990s.
A nuller is an optical tool used to block a strong source so that fainter signals near that source can be observed. An example of a nuller is being employed on the Keck Interferometer. This causes the light from a star to destructively interfere, effectively cancelling the star's image. As a result, the faint light from a ring of dust orbiting the star can then be detected. This project is part of a scientific effort to detect and observe nearby planets.
Any planet is an extremely faint light source compared to its parent star. For example, a star like the Sun is about a billion times as bright as the reflected light from any of the planets orbiting it. In addition to the intrinsic difficulty of detecting such a faint light source, the light from the parent star causes a glare that washes it out. For those reasons, very few of the exoplanets reported as of April 2014 have been observed directly, with even fewer being resolved from their host star.
PlanetQuest is NASA's education and public outreach program centered on the science and technology of NASA's long-term search for habitable planets beyond the Solar System.
PEGASE is a design for a space observatory developed by France in the early 2000s. It combined formation flying with infrared telescopes operating as a double-aperture interferometer. Three free-flying satellites would operate together;a beam combiner and two siderostats. The baseline of the interferometer would be adjustable to between 50 and 500 meters. The goal of the mission is the study of Hot Jupiters ("pegasids"), brown dwarfs and the interior of protoplanetary disks. The design was developed by Centre National d'Études Spatiales and was studied for a launch as early as 2010–2012. However, the Phase-0 part of the study in 2005 suggested it would take 8 or 9 years to develop.
Heidi B. Hammel is a planetary astronomer who has extensively studied Neptune and Uranus. She was part of the team imaging Neptune from Voyager 2 in 1989. She led the team using the Hubble Space Telescope to view Shoemaker-Levy 9's impact with Jupiter in 1994. She has used the Hubble Space Telescope and the Keck Telescope to study Uranus and Neptune, discovering new information about dark spots, planetary storms and Uranus' rings. In 2002, she was selected as an interdisciplinary scientist for the James Webb Space Telescope.
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Large Interferometer For Exoplanets (LIFE) is a project started in 2017 to develop the science, technology and a roadmap for a space mission to detect and characterize the atmospheres of dozens of warm, terrestrial extrasolar planets. The current plan is for a nulling interferometer operating in the mid-infrared.
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