MESSENGER

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  • MESSENGER trajectory.svg
    Interplanetary trajectory of the MESSENGER orbiter.

    • Earth flyby

    MESSENGER performed an Earth flyby one year after launch, on August 2, 2005, with the closest approach at 19:13 UTC at an altitude of 2,347 kilometers (1,458 statute miles) over central Mongolia. On December 12, 2005, a 524-second-long burn (Deep-Space Maneuver or DSM-1) of the large thruster adjusted the trajectory for the upcoming Venus flyby by 316 m/s. [61]

    During the Earth flyby, the MESSENGER team imaged the Earth and Moon using MDIS and checked the status of several other instruments observing the atmospheric and surface compositions and testing the magnetosphere and determining that all instruments tested were working as expected. This calibration period was intended to ensure accurate interpretation of data when the spacecraft entered orbit around Mercury. Ensuring that the instruments functioned correctly at such an early stage in the mission allowed opportunity for multiple minor errors to be dealt with. [62]

    The Earth flyby was used to investigate the flyby anomaly, where some spacecraft have been observed to have trajectories that differ slightly from those predicted. However no anomaly was observed in MESSENGER's flyby. [63]

    Two Venus flybys

    On October 24, 2006, at 08:34 UTC, MESSENGER encountered Venus at an altitude of 2,992 kilometers (1,859 mi). During the encounter, MESSENGER passed behind Venus and entered superior conjunction, a period when Earth was on the exact opposite side of the Solar System, with the Sun inhibiting radio contact. For this reason, no scientific observations were conducted during the flyby. Communication with the spacecraft was reestablished in late November and performed a deep space maneuver on December 12, to correct the trajectory to encounter Venus in a second flyby. [64]

    On June 5, 2007, at 23:08 UTC, MESSENGER performed a second flyby of Venus at an altitude of 338 km (210 mi), for the greatest velocity reduction of the mission. During the encounter, all instruments were used to observe Venus and prepare for the following Mercury encounters. The encounter provided visible and near-infrared imaging data of the upper atmosphere of Venus. Ultraviolet and X-ray spectrometry of the upper atmosphere were also recorded, to characterize the composition. The ESA's Venus Express was also orbiting during the encounter, providing the first opportunity for simultaneous measurement of particle-and-field characteristics of the planet. [65]

    Three Mercury flybys

    MESSENGER made a flyby of Mercury on January 14, 2008 (making its closest approach of 200 km above the surface of Mercury at 19:04:39 UTC), followed by a second flyby on October 6, 2008. [11] MESSENGER executed a final flyby on September 29, 2009, further slowing down the spacecraft. [12] [13] Sometime during the closest approach of the last flyby, the spacecraft entered safe mode. Although this had no effect on the trajectory necessary for later orbit insertion, it resulted in the loss of science data and images that were planned for the outbound leg of the fly-by. The spacecraft had fully recovered by about seven hours later. [66] One last deep space maneuver, DSM-5, was executed on November 24, 2009, at 22:45 UTC to provide the required 0.177 kilometres per second (0.110 mi/s) velocity change for the scheduled Mercury orbit insertion on March 18, 2011, marking the beginning of the orbital mission. [67]

    Orbital insertion

    The thruster maneuver to insert the probe into Mercury's orbit began at 00:45 UTC on March 18, 2011. The 0.9 km/s (0.5 mi./sec.) braking maneuver lasted about 15 minutes, with confirmation that the craft was in Mercury orbit received at 01:10 UTC on March 18 (9:10 PM, March 17 EDT). [57] Mission lead engineer Eric Finnegan indicated that the spacecraft had achieved a near-perfect orbit. [68]

    MESSENGER's orbit was highly elliptical, taking it within 200 kilometers (120 mi) of Mercury's surface and then 15,000 km (9,300 mi) away from it every twelve hours. This orbit was chosen to shield the probe from the heat radiated by Mercury's hot surface. Only a small portion of each orbit was at a low altitude, where the spacecraft was subjected to radiative heating from the hot side of the planet. [69]

    Primary science

    After MESSENGER's orbital insertion, an eighteen-day commissioning phase took place. The supervising personnel switched on and tested the craft's science instruments to ensure they had completed the journey without damage. [70] The commissioning phase "demonstrated that the spacecraft and payload [were] all operating nominally, notwithstanding Mercury's challenging environment." [33]

    The primary mission began as planned on April 4, 2011, with MESSENGER orbiting Mercury once every twelve hours for an intended duration of twelve Earth months, the equivalent of two solar days on Mercury. [33] Principal Investigator Sean Solomon, then of the Carnegie Institution of Washington, said: "With the beginning today of the primary science phase of the mission, we will be making nearly continuous observations that will allow us to gain the first global perspective on the innermost planet. Moreover, as solar activity steadily increases, we will have a front-row seat on the most dynamic magnetosphere–atmosphere system in the Solar System." [33]

    On October 5, 2011, the scientific results obtained by MESSENGER during its first six terrestrial months in Mercury's orbit were presented in a series of papers at the European Planetary Science Congress in Nantes, France. [20] Among the discoveries presented were the unexpectedly high concentrations of magnesium and calcium found on Mercury's nightside, and the fact that Mercury's magnetic field is offset far to the north of the planet's center. [20]

    Extended mission

    Topography of Mercury based on MDIS (Mercury Dual Imaging System) data MercuryTopo.png
    Topography of Mercury based on MDIS (Mercury Dual Imaging System) data

    In November 2011, NASA announced that the MESSENGER mission would be extended by one year, allowing the spacecraft to observe the 2012 solar maximum. [1] Its extended mission began on March 17, 2012, and continued until March 17, 2013. Between April 16 and 20, 2012, MESSENGER carried out a series of thruster manoeuvres, placing it in an eight-hour orbit to conduct further scans of Mercury. [71]

    In November 2012, NASA reported that MESSENGER had discovered both water ice and organic compounds in permanently shadowed craters in Mercury's north pole. [21] [72] In February 2013, NASA published the most detailed and accurate 3D map of Mercury to date, assembled from thousands of images taken by MESSENGER. [73] [74] MESSENGER completed its first extended mission on March 17, 2013, [2] and its second lasted until April 2015. [19] In November 2013, MESSENGER was among the numerous space assets that imaged Comet Encke (2P/Encke) and Comet ISON (C/2012 S1). [75] [76] [77] As its orbit began to decay in early 2015, MESSENGER was able to take highly detailed close-up photographs of ice-filled craters and other landforms at Mercury's north pole. [78] After the mission was completed, review of the radio ranging data provided the first measurement of the rate of mass loss from the Sun. [79]

    Discovery of water, organic compounds and volcanism

    On July 3, 2008, the MESSENGER team announced that the probe had discovered large amounts of water present in Mercury's exosphere, which was an unexpected finding. [82] In the later years of its mission, MESSENGER also provided visual evidence of past volcanic activity on the surface of Mercury, [83] as well as evidence for a liquid iron planetary core. [82] The probe also constructed the most detailed and accurate maps of Mercury to date, and furthermore discovered carbon-containing organic compounds and water ice inside permanently shadowed craters near the north pole. [84]

    Solar System portrait

    On February 18, 2011, a portrait of the Solar System was published on the MESSENGER website. The mosaic contained 34 images, acquired by the MDIS instrument during November 2010. All the planets were visible with the exception of Uranus and Neptune, due to their vast distances from the Sun. The MESSENGER "family portrait" was intended to be complementary to the Voyager family portrait, which was acquired from the outer Solar System by Voyager 1 on February 14, 1990. [85]

    MESSENGER captured a near-complete portrait of the Solar System during November 2010. MESSENGER Solar System Family Portrait.jpg
    MESSENGER captured a near-complete portrait of the Solar System during November 2010.

    View of a total lunar eclipse

    A lunar eclipse as viewed from Mercury, captured from the MESSENGER spacecraft. The Moon can be seen falling into the shadow of Earth. MESSENGER views 2014-10-08 lunar eclipse from Mercury orbit.gif
    A lunar eclipse as viewed from Mercury, captured from the MESSENGER spacecraft. The Moon can be seen falling into the shadow of Earth.

    On October 8, 2014 from 9:18 UTC to 10:18 UTC, MESSENGER took 31 images taken two minutes apart of the Earth and the Moon, as the Moon underwent a total lunar eclipse. MESSENGER was 107 million kilometers (66 million miles) from the Earth at the time of the lunar eclipse. The Earth is about 5 pixels across and the Moon is just over 1 pixel across in the field of view of the NAC, with about 40 pixels distance between them. The images are zoomed by a factor of two and the Moon's brightness has been increased by a factor of about 25 to show its disappearance more clearly. This was the first observation of a lunar eclipse, of Earth's Moon, in history to be viewed from another planet. [86] [17]

    End of mission

    After running out of propellant for course adjustments, MESSENGER entered its expected terminal phase of orbital decay in late 2014. The spacecraft's operation was extended by several weeks by exploiting its remaining supply of helium gas, which was used to pressurize its propellant tanks, as reaction mass. [87] MESSENGER continued studying Mercury during its decay period. [3] The spacecraft crashed onto the surface of Mercury on April 30, 2015, at 3:26 p.m. EDT (19:26 GMT), at a velocity of 14,080 km/h (8,750 mph), probably creating a crater in the planet's surface approximately 16 m (52 ft) wide. [18] [88] The spacecraft was estimated to have impacted at 54.4° N, 149.9° W on Suisei Planitia, near the crater Janáček. [89] The crash occurred at a place not visible from Earth at the time, and thus was not detected by any observers or instruments. NASA confirmed the end of the MESSENGER mission at 3:40 p.m. EDT (19:40 GMT) after NASA's Deep Space Network did not detect the spacecraft's reemergence from behind Mercury. [88] [90]

    MESSENGER's first (March 29, 2011) and last (April 30, 2015) images from Mercury's orbit (impact details). PIA19449-PlanetMercury-MESSENGER-Images-First-20110329-Last-20150430.jpg
    MESSENGER's first (March 29, 2011) and last (April 30, 2015) images from Mercury's orbit (impact details).

    See also

    Related Research Articles

    <span class="mw-page-title-main">Mercury (planet)</span> First planet from the Sun

    Mercury is the first planet from the Sun and the smallest in the Solar System. In English, it is named after the Roman god Mercurius (Mercury), god of commerce and communication, and the messenger of the gods. Mercury is classified as a terrestrial planet, with roughly the same surface gravity as Mars. The surface of Mercury is heavily cratered, as a result of countless impact events that have accumulated over billions of years. Its largest crater, Caloris Planitia, has a diameter of 1,550 km (960 mi) and one-third the diameter of the planet. Similarly to the Earth's Moon, Mercury's surface displays an expansive rupes system generated from thrust faults and bright ray systems formed by impact event remnants.

    <span class="mw-page-title-main">Mariner program</span> NASA space program from 1962 to 1973

    The Mariner program was conducted by the American space agency NASA to explore other planets. Between 1962 and late 1973, NASA's Jet Propulsion Laboratory (JPL) designed and built 10 robotic interplanetary probes named Mariner to explore the inner Solar System - visiting the planets Venus, Mars and Mercury for the first time, and returning to Venus and Mars for additional close observations.

    <span class="mw-page-title-main">Space exploration</span> Exploration of space, planets, and moons

    Space exploration is the use of astronomy and space technology to explore outer space. While the exploration of space is currently carried out mainly by astronomers with telescopes, its physical exploration is conducted both by uncrewed robotic space probes and human spaceflight. Space exploration, like its classical form astronomy, is one of the main sources for space science.

    <i>Mariner 10</i> 1973 American robotic space probe; flew by Venus and Mercury

    Mariner 10 was an American robotic space probe launched by NASA on 3 November 1973, to fly by the planets Mercury and Venus. It was the first spacecraft to perform flybys of multiple planets.

    <span class="mw-page-title-main">Gravity assist</span> Space navigation technique

    A gravity assist, gravity assist maneuver, swing-by, or generally a gravitational slingshot in orbital mechanics, is a type of spaceflight flyby which makes use of the relative movement and gravity of a planet or other astronomical object to alter the path and speed of a spacecraft, typically to save propellant and reduce expense.

    <span class="mw-page-title-main">Lander (spacecraft)</span> Type of spacecraft

    A lander is a spacecraft that descends towards, then comes to rest on the surface of an astronomical body other than Earth. In contrast to an impact probe, which makes a hard landing that damages or destroys the probe upon reaching the surface, a lander makes a soft landing after which the probe remains functional.

    <i>Magellan</i> (spacecraft) NASA mission to map the surface of Venus via robotic probe (launched 1989)

    The Magellan spacecraft was a 1,035-kilogram (2,282 lb) robotic space probe launched by NASA of the United States, on May 4, 1989, to map the surface of Venus by using synthetic-aperture radar and to measure the planetary gravitational field.

    <i>New Horizons</i> NASA probe that visited Pluto and Kuiper belt object 486958 Arrokoth

    New Horizons is an interplanetary space probe launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research Institute (SwRI), with a team led by Alan Stern, the spacecraft was launched in 2006 with the primary mission to perform a flyby study of the Pluto system in 2015, and a secondary mission to fly by and study one or more other Kuiper belt objects (KBOs) in the decade to follow, which became a mission to 486958 Arrokoth. It is the fifth space probe to achieve the escape velocity needed to leave the Solar System.

    <span class="mw-page-title-main">Discovery Program</span> Ongoing solar system exploration program by NASA

    The Discovery Program is a series of Solar System exploration missions funded by the U.S. 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.

    <span class="mw-page-title-main">BepiColombo</span> European–Japanese satellites heading to Mercury

    BepiColombo is a joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. The mission comprises two satellites launched together: the Mercury Planetary Orbiter (MPO) and Mio. The mission will perform a comprehensive study of Mercury, including characterization of its magnetic field, magnetosphere, and both interior and surface structure. It was launched on an Ariane 5 rocket on 20 October 2018 at 01:45 UTC, with an arrival at Mercury planned for on 5 December 2025, after a flyby of Earth, two flybys of Venus, and six flybys of Mercury. The mission was approved in November 2009, after years in proposal and planning as part of the European Space Agency's Horizon 2000+ programme; it is the last mission of the programme to be launched.

    <span class="mw-page-title-main">Geology of Mercury</span> Geologic structure and composition of planet Mercury

    The geology of Mercury is the scientific study of the surface, crust, and interior of the planet Mercury. It emphasizes the composition, structure, history, and physical processes that shape the planet. It is analogous to the field of terrestrial geology. In planetary science, the term geology is used in its broadest sense to mean the study of the solid parts of planets and moons. The term incorporates aspects of geophysics, geochemistry, mineralogy, geodesy, and cartography.

    <span class="mw-page-title-main">Observations and explorations of Venus</span>

    Observations of the planet Venus include those in antiquity, telescopic observations, and from visiting spacecraft. Spacecraft have performed various flybys, orbits, and landings on Venus, including balloon probes that floated in the atmosphere of Venus. Study of the planet is aided by its relatively close proximity to the Earth, compared to other planets, but the surface of Venus is obscured by an atmosphere opaque to visible light.

    <span class="mw-page-title-main">Exploration of Mercury</span> Sending probes to the snallest planet

    The exploration of Mercury has a minor role in the space interests of the world. It is the least explored inner planet. As of 2015, the Mariner 10 and MESSENGER missions have been the only missions that have made close observations of Mercury. MESSENGER made three flybys before entering orbit around Mercury. A third mission to Mercury, BepiColombo, a joint mission between the Japan Aerospace Exploration Agency (JAXA) and the European Space Agency, is to include two probes. MESSENGER and BepiColombo are intended to gather complementary data to help scientists understand many of the mysteries discovered by Mariner 10's flybys.

    <span class="mw-page-title-main">Atmosphere of Mercury</span> Composition and properties of the atmosphere of the innermost planet of the Solar System

    Mercury, being the closest to the Sun, with a weak magnetic field and the smallest mass of the recognized terrestrial planets, has a very tenuous and highly variable atmosphere containing hydrogen, helium, oxygen, sodium, calcium, potassium and water vapor, with a combined pressure level of about 10−14 bar. The exospheric species originate either from the Solar wind or from the planetary crust. Solar light pushes the atmospheric gases away from the Sun, creating a comet-like tail behind the planet.

    <span class="mw-page-title-main">Parker Solar Probe</span> NASA robotic space probe of the outer corona of the Sun

    The Parker Solar Probe is a NASA space probe launched in 2018 with the mission of making observations of the outer corona of the Sun. It will approach to within 9.86 solar radii from the center of the Sun, and by 2025 will travel, at closest approach, as fast as 690,000 km/h (430,000 mph) or 191 km/s, which is 0.064% the speed of light. It is the fastest object ever built.

    <span class="mw-page-title-main">Mars flyby</span> Spacecraft maneuver

    A Mars flyby is a movement of spacecraft passing in the vicinity of the planet Mars, but not entering orbit or landing on it. Uncrewed space probes have used this method to collect data on Mars, as opposed to orbiting or landing. A spacecraft designed for a flyby is also known as a "flyby bus" or "flyby spacecraft".

    The following outline is provided as an overview of and topical guide to Venus:

    References

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    61. ↑ "MESSENGER Engine Burn Puts Spacecraft on Track for Venus" (Press release). Johns Hopkins University. December 12, 2005. Retrieved May 1, 2009.
    62. ↑ "MESSENGER Status Report" (Press release). NASA/APL. August 26, 2005. Archived from the original on May 13, 2013. Retrieved March 17, 2011.
    63. ↑ Anderson, J. D.; Campbell, J. K.; Ekelund, J. E.; Ellis, J.; Jordan, J. F. (2008). "Anomalous orbital-energy changes observed during spacecraft flybys of Earth". Physical Review Letters. 100 (9): 091102. Bibcode:2008PhRvL.100i1102A. doi:10.1103/physrevlett.100.091102. PMID   18352689.
    64. ↑ "MESSENGER Completes Venus Flyby" (Press release). NASA/APL. October 24, 2006. Archived from the original on May 13, 2013. Retrieved March 17, 2011.
    65. ↑ "Critical Deep-Space Maneuver Targets MESSENGER for Its First Mercury Encounter" (Press release). Johns Hopkins University. October 17, 2007. Archived from the original on December 1, 2008. Retrieved May 1, 2009.
    66. ↑ "MESSENGER Gains Critical Gravity Assist for Mercury Orbital Observations". MESSENGER Mission News. September 30, 2009. Archived from the original on May 10, 2013. Retrieved September 30, 2009.
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    68. ↑ Amos, Jonathan (March 18, 2011). "Messenger probe enters Mercury orbit". BBC. Retrieved April 30, 2023.
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    86. ↑ "Lunar Eclipse From Mercury". NASA. Retrieved April 20, 2024.PD-icon.svg This article incorporates text from this source, which is in the public domain .
    87. ↑ "Innovative use of pressurant extends MESSENGER's Mercury mission". Astronomy.com. December 29, 2014. Retrieved January 22, 2015.
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    MESSENGER
    MESSENGER - spacecraft at mercury - atmercury lg.jpg
    Artist's rendering of MESSENGER orbiting Mercury
    Mission type Mercury probe
    Operator NASA
    COSPAR ID 2004-030A OOjs UI icon edit-ltr-progressive.svg
    SATCAT no. 28391
    Website messenger.jhuapl.edu
    Mission durationTotal:
    10 years, 8 months and 27 days
    At Mercury:
    4 years, 1 month and 14 days
    En route: 7 years
    Primary mission: 1 year
    First extension: 1 year [1] [2]
    Second extension: 2 years [3] [4]
    Spacecraft properties
    Manufacturer Applied Physics Laboratory
    Launch mass1,107.9 kg (2,443 lb) [5]
    Power450 watts
    Start of mission
    Launch dateAugust 3, 2004, 06:15:56 (2004-08-03UTC06:15:56Z) UTC
    Rocket Delta II 7925H-9.5
    Launch site Cape Canaveral SLC-17B
    Entered serviceApril 4, 2011
    End of mission
    DisposalCrashed into Mercury
    DestroyedApril 30, 2015 at 19:26 UT [6]
    Orbital parameters
    Reference system Hermiocentric
    Perihermion altitude 200 kilometers (120 mi)
    Apohermion altitude 10,300 kilometers (6,400 mi)
    Inclination 80 degrees
    Period 12 hours
    Epoch January 1, 2000 [7]
    Flyby of Earth (gravity assist)
    Closest approachAugust 2, 2005
    Distance2,347 kilometers (1,458 mi)
    New Horizons spacecraft model 1.png
    Proposals
    Finalists
    Candidates
    • Underline indicates active current missions
    • Italics indicate missions yet to launch
    • Symbol † indicates failure en route or before intended mission data returned
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