View source for Astronomy:Comet Hopper

{{Infobox spaceflight
| name                  = Comet Hopper
| names_list            = CHopper<!--list of previous names if the spacecraft has been renamed. 
Include the dates applicable if possible, and separate each name with a linebreak. 
Omit if the spacecraft has only ever been known by one name. 
Do not include Harvard, COSPAR/NSSDC or SATCAT/NORAD/NASA designations as alternative names-->

<!--image of the spacecraft/mission-->
| image                 = <!--omit the "file" prefix-->
| image_caption         = <!--image caption-->
| image_alt             = <!--image alt text-->
| image_size            = <!--include px/em; defaults to 220px-->

<!--Basic details-->
| mission_type          = <!--eg. Technology, Reconnaissance, ISS assembly, etc-->
| operator              = Under evaluation by [[Organization:NASA|NASA]]
| Harvard_designation   = <!--spacecraft launched 1962 and earlier only (eg. 1957 Alpha 2)-->
| COSPAR_ID             = <!--spacecraft launched since 1963 only (aka NSSDC ID; eg. 1998-067A)-->
| SATCAT                = <!--satellite catalogue number, omit leading zeroes (e.g. 25544)-->
| website               = <!--Homepage of the craft/mission, OFFICIAL PAGES ONLY-->
| mission_duration      = 7.3 years (proposed)
| distance_travelled    = <!--How far the spacecraft travelled (if known)-->
| orbits_completed      = <!--number of times the spacecraft orbited the Earth - see below for spacecraft beyond Earth orbit-->
| suborbital_range      = <!--downrange distance reached if spacecraft did not enter orbit-->
| suborbital_apogee     = <!--altitude reached if spacecraft did not enter orbit-->

<!--Spacecraft properties-->
| spacecraft            = <!--Spacecraft name/serial number (eg. Space Shuttle ''Discovery'', Apollo CM-118), etc-->
| spacecraft_type       = <!--eg. GPS Block II, Kobalt-M, US-K, etc-->
| spacecraft_bus        = <!--eg. A2100M, Star-2, etc-->
| manufacturer          = [[Organization:University of Maryland, College Park|UMD]]<br>[[Company:Lockheed Martin|Lockheed Martin]]<br>GSFC
| launch_mass           = <!--fuelled mass at launch, not including rocket or upper stage-->
| BOL_mass              = <!--spacecraft mass in orbit at beginning of operational life, after LEOP phase-->
| landing_mass          = <!--Mass after landing (recovered spacecraft only)-->
| dry_mass              = <!--spacecraft mass in orbit without fuel-->
| payload_mass          = <!--Mass of cargo carried by spacecraft (eg. for Space Shuttle), or total mass of instrumentation/equipment/experiments for mission-->
| dimensions            = <!--body dimensions and solar array span-->
| power                 = <!--end-of-life power, in watts-->

<!--Launch details-->
| launch_date           = Cancelled; 2016 (was proposed)<!--{{start date|YYYY|MM|DD|hh|mm|ss|TZ=Z}}-->
| launch_rocket         = [[Engineering:Atlas V|Atlas V]]
| launch_site           = <!--Where the rocket launched from, including complex and pad; do not include the full address or country-->
| launch_contractor     = <!--organisation(s) that conducted the launch (eg. United Launch Alliance, Arianespace, etc)-->
| deployment_from       = <!--place where deployed from-->
| deployment_date       = <!--date deployed-->
| entered_service       = <!--date on which the spacecraft entered service, if it did not do so immediately after launch-->
<!-- * - e.g. Proton-M/Briz-M not Proton-M, but Titan IV(401)A not Titan IV(401)A-Centaur-->

<!--end of mission-->
| disposal_type         = <!--Whether the spacecraft was deorbited, decommissioned, placed in a graveyard orbit, etc-->
| deactivated           = <!--when craft was decommissioned-->
| destroyed             = <!--when craft was destroyed (if other than by re-entry)-->
| last_contact          = <!--when last signal received if not decommissioned-->
| recovery_by           = <!--recovered by-->
| recovery_date         = <!--recovery date-->
| decay_date            = <!--when craft re-entered the atmosphere, not needed if it landed-->
| landing_date          = <!--when the spacecraft made a controlled landing, not needed if it did not return intact-->
| landing_site          = <!--where the craft landed; site/runway or coordinates-->
<!--
    The following template should be used for ONE of the three above fields "end_of_mission", "decay" or "landing" if the spacecraft is no longer operational.
    If it landed intact, use it for the landing time, otherwise for the date it ceased operations, or the decay date if it was still operational when it re-entered.
    {{end date|YYYY|MM|DD|hh|mm|ss|TZ=Z}} (for Zulu/UTC) or {{end date|YYYY|MM|DD}} (if time unknown) 
-->

<!--orbit parameters-->
<!--as science-related articles, SI units should be the principal units of measurement, however we usually use {{convert}} to display imperial units in parentheses after the initial values-->
| orbit_reference       = <!--geocentric, selenocentric, etc - please link (e.g. [[Astronomy:Geocentric orbit|Geocentric]])-->
| orbit_regime          = <!--high, low, medium, molniya, GSO - please link (e.g. [[Astronomy:Low Earth orbit|Low Earth]] - please don't use acronyms-->
| orbit_longitude       = <!--geosynchronous satellites only-->
| orbit_slot            = <!--Designation of orbital position or slot, if not longitude (e.g plane and position of a GPS satellite)-->
| orbit_semimajor       = <!--semimajor axis-->
| orbit_eccentricity    = <!--orbital eccentricity-->
| orbit_periapsis       = <!--periapsis altitude--> 
| orbit_apoapsis        = <!--apoapsis altitude--> 
| orbit_inclination     = <!--orbital inclination--> 
| orbit_period          = <!--time taken to complete an orbit-->
| orbit_RAAN            = <!--right ascension of the ascending node-->
| orbit_arg_periapsis   = <!--argument of perigee/periapsis-->
| orbit_mean_anomaly    = <!--mean anomaly at epoch, only use in conjunction with an epoch value-->
| orbit_mean_motion     = <!--mean motion of the satellite, usually measured in orbits per day-->
| orbit_repeat          = <!--repeat interval/revisit time-->
| orbit_velocity        = <!--speed at which the spacecraft was travelling at epoch - only use for spacecraft with low orbital eccentricity-->
| orbit_epoch           = <!--the date at which the orbit parameters were correct-->
| orbit_rev_number      = <!--revolution number-->
| apsis                 = <!--planet specific apsis term (eg. gee/helion/selene/etc - defaults to generic "apsis")-->

|interplanetary         = <!--Infobox spaceflight/IP can be called multiple times for missions with multiple targets or combined orbiter/lander missions, etc-->
 {{Infobox spaceflight/IP
   |type                = lander
   |object              = Comet Wirtanen
   |orbits              = <!--number of orbits completed at target body (if applicable and known)-->
   |component           = <!--part of the spacecraft involved, if spacecraft split into multiple components-->
   |arrival_date        = Cancelled; 2022 (was proposed)
   |departure_date      = <!--Date of leaving orbit for orbiters, date of launch for landers which took off again-->
   |location            = <!--landing/impact site, including EOM impacts for atmospheric probes and lunar/asteroid orbiters-->
   |distance            = <!--closest approach distance for flybys, distance travelled on surface for rovers, omit for others-->
 }}

<!--transponder parameters-->
| trans_band            = <!--Transponder frequency bands-->
| trans_frequency       = <!--specific frequencies-->
| trans_bandwidth       = <!--bandwidth-->
| trans_capacity        = <!--capacity of the transponders-->
| trans_coverage        = <!--area covered-->
| trans_TWTA            = <!--TWTA output power-->
| trans_EIRP            = <!--equivalent isotropic power-->
| trans_HPBW            = <!--half-power beam width-->

<!--Only use where a spacecraft/mission is part of a clear programme of sequential missions. 
If in doubt, leave it out-->
| programme             = 
| previous_mission      =
| next_mission          =

<!--mission insignia or patch-->
| insignia              = <!--omit the "file" prefix-->
| insignia_caption      = <!--image caption-->
| insignia_alt          = <!--image alt text-->
| insignia_size         = <!--include px/em; defaults to 180px-->

<!--Instruments-->
|instruments_list=
 {{Infobox spaceflight/Instruments
  |acronym1 = CHIRS
  |acronym2 = CHIMS
  |acronym3 = CHI
  |acronym4 = CHEX
  |acronym5 = PanCams

  |name1 = CHopper [[Physics:Infrared spectroscopy|Infrared Spectrometer]]
  |name2 = CHopper Ion/Neutral Mass Spectrometer
  |name3 = CHopper Imager
  |name4 = CHopper Heating Experiment
  |name5 = Panoramic Cameras
 }}
}}

'''Comet Hopper''' ('''CHopper''') was a proposed [[Engineering:Lander (spacecraft)|lander]] to [[Organization:NASA|NASA's]] [[Astronomy:Discovery Program|Discovery Program]] that, had it been selected, would have orbited and landed multiple times on Comet Wirtanen as it approached the [[Astronomy:Sun|Sun]]. The proposed mission was led by Jessica Sunshine of the [[Organization:University of Maryland, College Park|UMD]], working with [[Company:Lockheed Martin|Lockheed Martin]] to build the [[Engineering:Spacecraft|spacecraft]] and the NASA Goddard Spaceflight Center to manage the mission.<ref name="AdamsBrief">{{cite web|title=Planetary Science Division Update|publisher=[[Organization:NASA|NASA]]|url=http://solarsystem.nasa.gov/docs/Adams%20PPS%2005102011.pdf|access-date=May 23, 2011|archive-url=https://web.archive.org/web/20111114141842/http://solarsystem.nasa.gov/docs/Adams%20PPS%2005102011.pdf|archive-date=November 14, 2011|url-status=dead}}</ref>

==History==
The Comet Hopper mission was one of three [[Astronomy:Discovery Program|Discovery Program]] finalists that received {{USD|3}} million in May 2011 to develop a detailed concept study.<ref name='Taylor'>{{cite news | author = Taylor, Kate | title = NASA picks project shortlist for next Discovery mission | date = 9 May 2011 | url = http://www.tgdaily.com/space-features/55816-nasa-picks-project-shortlist-for-next-discovery-mission | work = TG Daily | access-date = 28 October 2015 | archive-date = 6 October 2018 | archive-url = https://web.archive.org/web/20181006212756/https://www.tgdaily.com/space-features/55816-nasa-picks-project-shortlist-for-next-discovery-mission | url-status = dead }}</ref>

The other two missions were [[Astronomy:InSight|InSight]] and Titan Mare Explorer. After a review in August 2012, NASA selected the InSight mission.<ref>{{cite news |url=https://www.washingtonpost.com/national/health-science/nasa-will-send-robot-drill-to-mars-in-2016/2012/08/20/43bf1980-eaef-11e1-9ddc-340d5efb1e9c_story.html |title=NASA will send robot drill to Mars in 2016 |newspaper={{wipe|The Washington Post}} |first=Brian |last=Vastag |date=August 20, 2012}}</ref>

== Scientific goals ==
The CHopper mission had three primary science goals for the 7.3 years of its lifetime. At roughly 4.5 [[Astronomy:Astronomical unit|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 [[Astronomy:Coma (cometary)|coma]] - the nebulous envelope around the [[Astronomy:Comet nucleus|nucleus]] of a [[Astronomy:Comet|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.<ref name="AdamsBrief" /><ref name="BaltSun_MD">{{cite web|title=Maryland scientists vie for NASA missions|newspaper=The Baltimore Sun|url=http://articles.baltimoresun.com/2011-05-29/news/bs-md-time-chopper-missions-20110529_1_nasa-missions-nasa-funding-bruce-banerdt/3|access-date=June 2, 2011|url-status=dead|archiveurl=https://web.archive.org/web/20120926001329/http://articles.baltimoresun.com/2011-05-29/news/bs-md-time-chopper-missions-20110529_1_nasa-missions-nasa-funding-bruce-banerdt/3|archivedate=September 26, 2012}}</ref> The final landing would occur at 1.5 AU.

{{Clear}}

==See also==
* [[Engineering:Champollion (spacecraft)|Champollion (spacecraft)]]
* [[Astronomy:Mars Geyser Hopper|Mars Geyser Hopper]]
* [[Engineering:Rosetta (spacecraft)|Rosetta (spacecraft)]]
*[[Astronomy:Triton Hopper|Triton Hopper]]

== References ==
{{Reflist|2}}

== External links ==
;Press Releases
:* [http://www.nasa.gov/centers/goddard/news/releases/2011/11-033.html NASA Goddard Managed Comet Hopper Mission Selected for Further Study] {{Webarchive|url=https://web.archive.org/web/20211205221451/https://www.nasa.gov/centers/goddard/news/releases/2011/11-033.html |date=2021-12-05 }}
:* [https://web.archive.org/web/20140122095251/https://www.newsdesk.umd.edu/scitech/release.cfm?ArticleID=2428 Comet Hopper, a UMD/NASA Goddard Proposal, Moves to 'Final Round' in NASA Selection Process]
;News Articles
:* [https://web.archive.org/web/20120926001329/http://articles.baltimoresun.com/2011-05-29/news/bs-md-time-chopper-missions-20110529_1_nasa-missions-nasa-funding-bruce-banerdt/3 Maryland scientists vie for NASA missions]

{{Planetary Missions Program Office|Discovery=y}}
{{Comet spacecraft}}

[[Category:Cancelled spacecraft]]
[[Category:Missions to comets]]
[[Category:Advanced Stirling radioisotope generator]]

{{Sourceattribution|Comet Hopper}}