| Names | CHopper | ||||||||||||
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| Operator | Under evaluation by NASA | ||||||||||||
| Mission duration | 7.3 years (proposed) | ||||||||||||
| Spacecraft properties | |||||||||||||
| Manufacturer | UMD Lockheed Martin GSFC | ||||||||||||
| Start of mission | |||||||||||||
| Launch date | Cancelled; 2016 (was proposed) | ||||||||||||
| Rocket | Atlas V | ||||||||||||
| Comet Wirtanen lander | |||||||||||||
| Landing date | Cancelled; 2022 (was proposed) | ||||||||||||
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Comet Hopper (CHopper) was a proposed lander to NASA's Discovery Program that, had it been selected, would have orbited and landed multiple times on Comet Wirtanen as it approached the Sun. The proposed mission was led by Jessica Sunshine of the UMD, working with Lockheed Martin to build the spacecraft and the NASA Goddard Spaceflight Center to manage the mission. [1]
The Comet Hopper mission was one of three Discovery Program finalists that received US$3 million in May 2011 to develop a detailed concept study. [2]
The other two missions were InSight and Titan Mare Explorer. After a review in August 2012, NASA selected the InSight mission. [3]
The CHopper mission had three primary science goals for the 7.3 years of its lifetime. At roughly 4.5 AU the spacecraft would have rendezvoused with Comet Wirtanen to map the spatial heterogeneity of surface solids as well as gas and dust emissions from the coma - the nebulous envelope around the nucleus of a comet. The remote mapping would also allow for any nucleus structure, geologic processes, and coma mechanisms to be determined. After arriving at Comet Wirtanen, the spacecraft would have approached and landed, then subsequently hopped to other locations on the comet. As the comet approached the sun, the spacecraft would land and hop multiple times to record surface changes as the comet became more active. [1] [4] The final landing would occur at 1.5 AU.
The Comet Nucleus Tour (CONTOUR) was a NASA Discovery-class space probe that failed shortly after its July 2002 launch. It had as its primary objective close flybys of two comet nuclei with the possibility of a flyby of a third known comet or an as-yet-undiscovered comet.
In the context of spaceflight, launch period is the collection of days and launch window is the time period on a given day during which a particular rocket must be launched in order to reach its intended target. If the rocket is not launched within a given window, it has to wait for the window on the next day of the period. Launch periods and launch windows are very dependent on both the rocket's capability and the orbit to which it is going.
Rosetta was a space probe built by the European Space Agency launched on 2 March 2004. Along with Philae, its lander module, Rosetta performed a detailed study of comet 67P/Churyumov–Gerasimenko (67P). During its journey to the comet, the spacecraft performed flybys of Earth, Mars, and the asteroids 21 Lutetia and 2867 Šteins. It was launched as the third cornerstone mission of the ESA's Horizon 2000 programme, after SOHO / Cluster and XMM-Newton.
Stardust was a 390-kilogram robotic space probe launched by NASA on 7 February 1999. Its primary mission was to collect dust samples from the coma of comet Wild 2, as well as samples of cosmic dust, and return them to Earth for analysis. It was the first sample return mission of its kind. En route to comet Wild 2, it also flew by and studied the asteroid 5535 Annefrank. The primary mission was successfully completed on 15 January 2006 when the sample return capsule returned to Earth.
The Discovery Program is a series of Solar System exploration missions funded by the US National Aeronautics and Space Administration (NASA) through its Planetary Missions Program Office. The cost of each mission is capped at a lower level than missions from NASA's New Frontiers or Flagship Programs. As a result, Discovery missions tend to be more focused on a specific scientific goal rather than serving a general purpose.
67P/Churyumov–Gerasimenko is a Jupiter-family comet, originally from the Kuiper belt, with a current orbital period of 6.45 years, a rotation period of approximately 12.4 hours and a maximum velocity of 135,000 km/h. Churyumov–Gerasimenko is approximately 4.3 by 4.1 km at its longest and widest dimensions. It was first observed on photographic plates in 1969 by Soviet astronomers Klim Ivanovych Churyumov and Svetlana Ivanovna Gerasimenko, after whom it is named. It most recently came to perihelion on 2 November 2021, and will next come to perihelion on 9 April 2028.
46P/Wirtanen is a small short-period comet with a current orbital period of 5.4 years. It was the original target for close investigation by the Rosetta spacecraft, planned by the European Space Agency, but an inability to meet the launch window caused Rosetta to be sent to 67P/Churyumov–Gerasimenko instead. It belongs to the Jupiter family of comets, all of which have aphelia between 5 and 6 AU. Its diameter is estimated at 1.2 kilometres (0.75 mi). In December 2019, astronomers reported capturing an outburst of the comet in substantial detail by the TESS space telescope.
Deep Impact is a NASA space probe launched from Cape Canaveral Air Force Station on January 12, 2005. It was designed to study the interior composition of the comet Tempel 1 (9P/Tempel), by releasing an impactor into the comet. At 05:52 UTC on July 4, 2005, the Impactor successfully collided with the comet's nucleus. The impact excavated debris from the interior of the nucleus, forming an impact crater. Photographs taken by the spacecraft showed the comet to be more dusty and less icy than had been expected. The impact generated an unexpectedly large and bright dust cloud, obscuring the view of the impact crater.
The coma is the nebulous envelope around the nucleus of a comet, formed when the comet passes close to the Sun on its highly elliptical orbit; as the comet warms, parts of it sublimate. This gives a comet a "fuzzy" appearance when viewed in telescopes and distinguishes it from stars. The word coma comes from the Greek "kome" (κόμη), which means "hair" and is the origin of the word comet itself.
The Comet Rendezvous Asteroid Flyby (CRAF) was a cancelled plan for a NASA-led exploratory mission designed by the Jet Propulsion Laboratory during the mid-to-late 1980s and early 1990s, that planned to send a spacecraft to encounter an asteroid, and then to rendezvous with a comet and fly alongside it for nearly three years. The project was eventually canceled when it went over budget; most of the money still left was redirected to its twin spacecraft, Cassini–Huygens, destined for Saturn, so it could survive Congressional budget cutbacks. Most of CRAF's scientific objectives were later accomplished by the smaller NASA spacecraft Stardust and Deep Impact, and by ESA's flagship Rosetta mission.
A sample-return mission is a spacecraft mission to collect and return samples from an extraterrestrial location to Earth for analysis. Sample-return missions may bring back merely atoms and molecules or a deposit of complex compounds such as loose material and rocks. These samples may be obtained in a number of ways, such as soil and rock excavation or a collector array used for capturing particles of solar wind or cometary debris. Nonetheless, concerns have been raised that the return of such samples to planet Earth may endanger Earth itself.
Comet Hartley 2, designated as 103P/Hartley by the Minor Planet Center, is a small periodic comet with an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit, Siding Spring Observatory, Australia. Its diameter is estimated to be 1.2 to 1.6 kilometres.
The Mars Geyser Hopper (MGH) is a NASA design reference mission for a Discovery-class spacecraft concept that would investigate the springtime carbon dioxide Martian geysers found in regions around the south pole of Mars.
C/2013 A1 is an Oort cloud comet discovered on 3 January 2013 by Robert H. McNaught at Siding Spring Observatory using the 0.5-meter (20 in) Uppsala Southern Schmidt Telescope.
A flyby is a spaceflight operation in which a spacecraft passes in proximity to another body, usually a target of its space exploration mission and/or a source of a gravity assist to impel it towards another target. Spacecraft which are specifically designed for this purpose are known as flyby spacecraft, although the term has also been used in regard to asteroid flybys of Earth for example. Important parameters are the time and distance of closest approach.
The selection process for Mission 13 and 14 of the Discovery program began in February 2014, as NASA drafted an Announcement of Opportunity (AO) for the next Discovery mission. The winning mission proposals received $450 million in funding towards mission development and construction, along with bonus funding if missions were able to incorporate certain technologies. For Discovery Mission 13 and 14, NASA received 28 proposals, 16 of which notably centered around small Solar System bodies. Lucy, a multiple-flyby mission to the Jupiter trojans, and Psyche, a mission to the metallic asteroid 16 Psyche, were announced as the winners of the competition in January 2017, with launches in October 2021 and October 2023, respectively.
Comet Rendezvous, Sample Acquisition, Investigation, and Return (CORSAIR) is a concept mission to return comet nucleus samples to Earth for detailed analysis. The mission concept was submitted in May 2017 by a team from NASA's Goddard Space Flight Center in response to the New Frontiers program call for mission 4, but did not pass the initial down selection. As a comet sample return mission was not ultimately selected for mission 4, the CORSAIR team may re-submit the concept to a future New Frontiers program call.
The Planetary Missions Program Office is a division of NASA headquartered at the Marshall Space Flight Center, formed by the agency's Science Mission Directorate (SMD). Succeeding the Discovery and New Frontiers Program Office, it was established in 2014 to manage the Discovery and New Frontiers programs of low and medium-cost missions by third-party institutions, and the Solar System Exploration program of NASA-led missions that focus on prioritized planetary science objectives. The Discovery and New Frontiers programs were established in 1992 and 2001 respectively, and have launched fourteen primary missions together, along with two missions launched under the administration of the Planetary Missions Program Office. The Solar System Exploration Program was established alongside the office, with three missions planned for launch under the new program.
Chimera is a NASA mission concept to orbit and explore 29P/Schwassmann-Wachmann 1 (SW1), an active, outbursting small icy body in the outer solar system. The concept was developed in response to the 2019 NASA call for potential missions in the Discovery-class, and it would have been the first spacecraft encounter with a Centaur and the first orbital exploration of a small body in the outer solar system. The Chimera proposal was ranked in the first tier of submissions, but was not selected for further development for the programmatic reason of maintaining scientific balance.
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