Editing Deep Space 1 (section)

==Mission overview==
{{multiple image |align=right |direction=horizontal |total_width=400
 |image1=Deep Space 1 Launch.png |caption1=Launch of DS1 aboard a Delta II from Cape Canaveral SLC-17A
 |image2=Animation of Deep Space 1 trajectory.gif |caption2=Animation of DS1{{'s}} trajectory from 24 October 1998 to 31 December 2003 <br/> {{legend2|magenta|''Deep Space 1''}}{{·}}{{legend2|lime|[[9969 Braille]]}}{{·}}{{legend2|royalblue|[[Earth]]}}{{·}}{{legend2|Cyan|[[19P/Borrelly]]}}
}}

Prior to launch, ''Deep Space 1'' was intended to visit comet [[76P/West–Kohoutek–Ikemura]] and asteroid [[3352 McAuliffe]].<ref name="comets">{{cite web |url=http://spider.seds.org/spider/Comets/c_missions.html |title=Comet Space Missions |website=SEDS.org |access-date=20 November 2016}}</ref> Because of the delayed launch, the targets were changed to asteroid [[9969 Braille]] (at the time called 1992&nbsp;KD) and comet [[19P/Borrelly]], with comet [[4015 Wilson–Harrington|107P/Wilson–Harrington]] being added following the early success of the mission.<ref name="results2001" /> It achieved an impaired flyby of Braille and, due to problems with the star tracker, abandoned targeting Wilson–Harrington in order to maintain its flyby of comet [[19P/Borrelly]], which was successful.<ref name="results2001" /> An August 2002 flyby of asteroid {{mpl|1999 KK|1}} as another extended mission was considered, but ultimately was not advanced on the basis that the scientific justification was not sufficiently strong when considering risk and cost.<ref name="wired20011218">{{cite magazine |url=https://www.wired.com/science/discoveries/news/2001/12/49210 |title=End of the Line for NASA Probe |magazine=[[Wired (magazine)|Wired]] |first=Noah |last=Schactman |date=18 December 2001 |archive-url=https://web.archive.org/web/20080617005731/http://www.wired.com/science/discoveries/news/2001/12/49210 |archive-date=17 June 2008 |url-status=dead}}</ref><ref name="rayman20011218">{{cite web |url=http://nmp.jpl.nasa.gov/ds1/arch/mrlog74.html |title=Mission Update |work=Dr. Marc Rayman's Mission Log |publisher=NASA/Jet Propulsion Laboratory |first=Marc |last=Rayman |date=18 December 2001 |archive-url=https://web.archive.org/web/20090813095208/http://nmp.jpl.nasa.gov/ds1/arch/mrlog74.html |archive-date=13 August 2009 |url-status=dead}}</ref> During the mission, high quality infrared spectra of [[Mars]] were also taken.<ref name="results2001" /><ref name="naif.ds1.mission" />

===Results and achievements===
[[File:Deep Space 1 spacecraft imaged by 5 meter Hale telescope on Palomar Mountain.png|thumb|Deep Space-1 as seen from [[Hale Telescope]] while at distance of {{convert|3.7|e6km|e6mi|abbr=unit}}]]
The ion propulsion engine initially failed after 4.5 minutes of operation. However, it was later restored to action and performed excellently. Early in the mission, material ejected during launch vehicle separation caused the closely spaced ion extraction grids to short-circuit. The contamination was eventually cleared, as the material was eroded by electrical arcing, sublimed by outgassing, or simply allowed to drift out. This was achieved by repeatedly restarting the engine in an engine repair mode, arcing across trapped material.<ref name="results2000">{{cite journal |url=http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/17743/1/99-1185.pdf |title=Results from the Deep Space 1 Technology Validation Mission |journal=Acta Astronautica |first1=Marc D. |last1=Rayman |first2=Philip |last2=Varghese |first3=David H. |last3=Lehman |first4=Leslie L. |last4=Livesay |volume=47 |issue=2–9 |pages=475–487 |date=July–November 2000 |doi=10.1016/S0094-5765(00)00087-4 |bibcode=2000AcAau..47..475R |url-status=dead |archive-url=https://web.archive.org/web/20120415134047/http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/17743/1/99-1185.pdf |archive-date=15 April 2012 |citeseerx=10.1.1.504.9572}}</ref>

It was thought that the ion engine exhaust might interfere with other spacecraft systems, such as radio communications or the science instruments. The PEPE detectors had a secondary function to monitor such effects from the engine. No interference was found although the flux of ions from the thruster prevented PEPE from observing ions below approximately 20 eV.

Another failure was the loss of the [[star tracker]]. The star tracker determines spacecraft orientation by comparing the star field to its internal charts. The mission was saved when the MICAS camera was reprogrammed to substitute for the star tracker. Although MICAS is more sensitive, its field-of-view is an order of magnitude smaller, creating a greater information processing burden. Ironically, the star tracker was an off-the-shelf component, expected to be highly reliable.<ref name="results2001">{{cite journal |url=http://nmp.jpl.nasa.gov/ds1/DS1_Extended_Mission.pdf |title=The Deep Space 1 Extended Mission |journal=Acta Astronautica |first1=Marc D. |last1=Rayman |first2=Philip |last2=Varghese |volume=48 |issue=5–12 |pages=693–705 |date=March–June 2001 |doi=10.1016/S0094-5765(01)00044-3 |bibcode=2001AcAau..48..693R |archive-url=https://web.archive.org/web/20090509104812/http://nmp.jpl.nasa.gov/ds1/DS1_Extended_Mission.pdf |archive-date=9 May 2009 |url-status=dead}}</ref>

Without a working star tracker, ion thrusting was temporarily suspended. The loss of thrust time forced the cancellation of a flyby past comet [[107P/Wilson–Harrington]].

The Autonav system required occasional manual corrections. Most problems were in identifying objects that were too dim, or were difficult to identify because of brighter objects causing diffraction spikes and reflections in the camera, causing Autonav to misidentify targets.

The Remote Agent system was presented with three simulated failures on the spacecraft and correctly handled each event.
# a failed electronics unit, which Remote Agent fixed by reactivating the unit.
# a failed sensor providing false information, which Remote Agent recognized as unreliable and therefore correctly ignored.
# an attitude control thruster (a small engine for controlling the spacecraft's orientation) stuck in the "off" position, which Remote Agent detected and compensated for by switching to a mode that did not rely on that thruster.
Overall this constituted a successful demonstration of fully autonomous planning, diagnosis, and recovery.

The MICAS instrument was a design success, but the ultraviolet channel failed due to an electrical fault.  Later in the mission, after the star tracker failure, MICAS assumed this duty as well.  This caused continual interruptions in its scientific use during the remaining mission, including the Comet Borrelly encounter.<ref name="results2003"/>

{{multiple image |align=right |direction=horizontal |total_width=400
 |image1=PIA01345.jpg |caption1=9969 Braille as imaged by DS1
 |image2=Comet Borrelly Nucleus.jpg |caption2=Comet 19P/Borrelly imaged just 160 seconds before DS1's closest approach
}}

The flyby of the asteroid [[9969 Braille]] was only a partial success. ''Deep Space 1'' was intended to perform the flyby at {{convert|56000|km/h|abbr=on}} at only {{convert|240|m|abbr=on}} from the asteroid. Due to technical difficulties, including a software crash shortly before approach, the craft instead passed Braille at a distance of {{convert|26|km|0|abbr=on}}. This, plus Braille's lower [[albedo]], meant that the asteroid was not bright enough for the Autonav to focus the camera in the right direction, and the picture shoot was delayed by almost an hour.<ref name="results2001"/>  The resulting pictures were disappointingly indistinct.

However, the flyby of Comet Borrelly was a great success and returned extremely detailed images of the comet's surface. Such images were of higher resolution than the only previous pictures of a comet -- [[Halley's Comet]], taken by the ''[[Giotto (spacecraft)|Giotto]]'' spacecraft. The PEPE instrument reported that the comet's solar wind interaction was offset from the nucleus. This is believed to be due to emission of jets, which were not distributed evenly across the comet's surface.

Despite having no debris shields, the spacecraft survived the comet passage intact. Once again, the sparse comet jets did not appear to point towards the spacecraft. ''Deep Space 1'' then entered its second extended mission phase, focused on retesting the spacecraft's hardware technologies. The focus of this mission phase was on the ion engine systems. The spacecraft eventually ran out of [[hydrazine]] fuel for its attitude control thrusters. The highly efficient ion thruster had a sufficient amount of propellant left to perform attitude control in addition to main propulsion, thus allowing the mission to continue.<ref name="results2003">{{cite journal |url=http://www.jpl.nasa.gov/nmp/ds1/DS1_conclusion.pdf |archive-url=https://web.archive.org/web/20161121171052/http://www.jpl.nasa.gov/nmp/ds1/DS1_conclusion.pdf |archive-date=2016-11-21 |url-status=live |title=The Successful Conclusion of the Deep Space 1 Mission: Important Results without a Flashy Title |journal=Space Technology |first=Marc D. |last=Rayman |volume=23 |issue=2 |pages=185–196 |date=2003}}</ref>

During late October and early November 1999, during the spacecraft's post-Braille encounter coast phase, ''Deep Space 1'' observed Mars with its MICAS instrument. Although this was a very distant flyby, the instrument did succeed in taking multiple infrared spectra of the planet.<ref name="results2001" /><ref name="naif.ds1.mission">{{cite web |url=http://naif.jpl.nasa.gov/pub/naif/pds/data/ds1-a_c-spice-6-v1.0/ds1sp_1000/catalog/mission.cat |title=Deep Space 1: Mission Information |publisher=NASA |date=29 September 2003 |access-date=20 November 2016}}</ref>

===Current status===
''Deep Space 1'' succeeded in its primary and secondary objectives, returning valuable science data and images. DS1's ion engines were shut down on 18 December 2001 at approximately 20:00:00&nbsp;UTC, signaling the end of the mission. On-board communications were set to remain in active mode in case the craft should be needed in the future. However, attempts to resume contact in March 2002 were unsuccessful.<ref name="results2003"/> It remains within the Solar System, in orbit around the Sun.<ref name="nssdc"/>