Английская Википедия:BepiColombo

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Шаблон:Short description Шаблон:Use British English Шаблон:Use dmy dates Шаблон:Infobox spaceflight

BepiColombo is a joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury.[1] The mission comprises two satellites launched together: the Mercury Planetary Orbiter (MPO) and Mio (Mercury Magnetospheric Orbiter, MMO).[2] 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[3] 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.[4][5] The mission was approved in November 2009, after years in proposal and planning as part of the European Space Agency's Horizon 2000+ programme;[6] it is the last mission of the programme to be launched.[7]

Names

BepiColombo is named after Giuseppe "Bepi" Colombo (1920–1984), a scientist, mathematician and engineer at the University of Padua, Italy, who first proposed the interplanetary gravity assist manoeuvre used by the 1974 Mariner 10 mission, a technique now used frequently by planetary probes.

Mio, the name of the Mercury Magnetospheric Orbiter, was selected from thousands of suggestions by the Japanese public. In Japanese, Mio means a waterway, and according to JAXA, it symbolizes the research and development milestones reached thus far, and wishes for safe travel ahead. JAXA said the spacecraft will travel through the solar wind just like a ship traveling through the ocean.[2] In Chinese and Japanese, Mercury is known as the "water star" (水星) according to wǔxíng.

Following its Earth flyby in April 2020, BepiColombo was briefly mistaken for a near-Earth asteroid, receiving the provisional designation Шаблон:Mp.[8][9][10][11]

Mission

The mission involves three components, which will separate into independent spacecraft upon arrival at Mercury.[12]

  • Mercury Transfer Module (MTM) for propulsion, built by ESA.
  • Mercury Planetary Orbiter (MPO) built by ESA.
  • Mercury Magnetospheric Orbiter (MMO) or Mio built by JAXA.

During the launch and cruise phases, these three components are joined together to form the Mercury Cruise System (MCS).

The prime contractor for ESA is Airbus Defence and Space.[13] ESA is responsible for the overall mission, the design, development assembly and test of the propulsion and MPO modules, and the launch. The two orbiters, which are operated by mission controllers based in Darmstadt, Germany, were successfully launched together on 20 October 2018.[14] The launch took place on Ariane flight VA245 from Europe’s Spaceport in Kourou, French Guiana.[15] The spacecraft will have a seven-year interplanetary cruise to Mercury using solar-electric propulsion (ion thrusters) and gravity assists from Earth, Venus and eventual gravity capture at Mercury.[4] ESA's Cebreros, Spain Шаблон:Convert ground station is planned to be the primary ground facility for communications during all mission phases.

Expected to arrive in Mercury orbit on 5 December 2025, the Mio and MPO satellites will separate and observe Mercury in collaboration for one year, with a possible one-year extension.[4] The orbiters are equipped with scientific instruments provided by various European countries and Japan. The mission will characterize the solid and liquid iron core (Шаблон:Frac of the planet's radius) and determine the size of each.[16] The mission will also complete gravitational and magnetic field mappings. Russia provided gamma ray and neutron spectrometers to verify the existence of water ice in polar craters that are permanently in shadow from the Sun's rays.

Mercury is too small and hot for its gravity to retain any significant atmosphere over long periods of time, but it has a "tenuous surface-bounded exosphere"[17] containing hydrogen, helium, oxygen, sodium, calcium, potassium and other trace elements. Its exosphere is not stable as atoms are continuously lost and replenished from a variety of sources. The mission will study the exosphere composition and dynamics, including generation and escape.

Objectives

The main objectives of the mission are:[18][19]

Design

Файл:MMO&MPO-Orbits.svg
Planned orbits for Mio and MPO satellites, the two probes of the BepiColombo mission

The stacked spacecraft will take seven years to position itself to enter Mercury orbit. During this time it will use solar-electric propulsion and nine gravity assists, flying past the Earth and Moon in April 2020, Venus in 2020 and 2021, and six Mercury flybys between 2021 and 2025.[4]

The stacked spacecraft left Earth with a hyperbolic excess velocity of Шаблон:Cvt. Initially, the craft was placed in a heliocentric orbit similar to that of Earth. After both the spacecraft and Earth completed one and a half orbits, it returned to Earth to perform a gravity-assist maneuver and is deflected towards Venus. Two consecutive Venus flybys reduce the perihelion near to the Sun–Mercury distance with almost no need for thrust. A sequence of six Mercury flybys will lower the relative velocity to Шаблон:Cvt. After the fourth Mercury flyby, the craft will be in an orbit similar to that of Mercury and will remain in the general vicinity of Mercury (see [1]). Four final thrust arcs reduce the relative velocity to the point where Mercury will "weakly" capture the spacecraft on 5 December 2025 into polar orbit. Only a small maneuver is needed to bring the craft into an orbit around Mercury with an apocentre of Шаблон:Convert. The orbiters then separate and will adjust their orbits using chemical thrusters.[22][23]

History

The BepiColombo mission proposal was selected by ESA in 2000. A request for proposals for the science payload was issued in 2004.[24] In 2007, Astrium was selected as the prime contractor, and Ariane 5 chosen as the launch vehicle.[24] The initial target launch of July 2014 was postponed several times, mostly because of delays on the development of the solar electric propulsion system.[24] The total cost of the mission was estimated in 2017 as US$2 billion.[25]

Schedule

Файл:Animation of BepiColombo trajectory.gif
Animation of BepiColomboШаблон:'s trajectory from 20 October 2018 to 2 November 2025
Шаблон:Legend2Шаблон:·Шаблон:Legend2Шаблон:·Шаблон:Legend2Шаблон:·Шаблон:Legend2Шаблон:·Шаблон:Legend2
For more detailed animation, see this video
Файл:BepiColombo’s second Mercury flyby.webm
Sequence of images taken during the second Mercury flyby
Файл:Animation of BepiColombo trajectory around Mercury.gif
Animation of BepiColombo's trajectory around Mercury

Шаблон:Asof, the mission schedule is:[4]

Date Event Comment
20 October 2018, 01:45 UTC Launch
10 April 2020,
04:25 UTC
Earth flyby 1.5 years after launch
15 October 2020, 03:58 UTC First Venus flyby According to Johannes Benkhoff of ESA, the probe may possibly be capable of detecting phosphine – the chemical allegedly discovered in the Venusian atmosphere in September 2020 – during this and the following flyby. He stated that "we do not know if our instrument is sensitive enough".[26] On 15 October 2020, the ESA reported the flyby was a success.[27]
10 August 2021,
13:51 UTC
Second Venus flyby 1.35 Venus years after first Venus flyby. Flyby was a success, and saw BepiColombo come within Шаблон:Convert of Venus' surface.[28][29]
1 October 2021,
23:34:41 UTC
First Mercury flyby Passed Шаблон:Convert from Mercury's surface.[30] Occurred on what would have been the 101st birthday of Giuseppe Colombo.
23 June 2022,
09:44 UTC
Second Mercury flyby 2 orbits (3.00 Mercury years) after 1st Mercury flyby. Closest approach of about Шаблон:Convert altitude.[31]
19 June 2023,
19:34 UTC
Third Mercury flyby >3 orbits (4.12 Mercury years) after 2nd Mercury flyby. Closest approach of about Шаблон:Convert altitude.[32][33]
Шаблон:Nowrap Fourth Mercury flyby ~4 orbits (5.04 Mercury years) after 3rd Mercury flyby
2 December 2024 Fifth Mercury flyby 1 orbit (1.00 Mercury year) after 4th Mercury flyby
9 January 2025 Sixth Mercury flyby ~0.43 orbits (0.43 Mercury years) after 5th Mercury flyby
5 December 2025 Mercury orbit insertion Spacecraft separation; 3.75 Mercury years after 6th Mercury flyby
14 March 2026 Шаблон:Nowrap 1.13 Mercury years after orbit insertion
1 May 2027 End of nominal mission 5.82 Mercury years after orbit insertion
1 May 2028 End of extended mission 9.98 Mercury years after orbit insertion
Файл:Timeline of BepiColombo.svg
Timeline of BepiColombo from 20 October 2018 to 2 November 2025. Red circle indicates flybys.

Components

Mercury Transfer Module

Файл:BepiColombo Earth Flyby 10 april 2020.gif
Earth flyby on 10 April 2020
Файл:BepiColombo NBO 2020-04-10.webm
BepiColombo, imaged at Northolt Branch Observatories, 16 hours after the Earth flyby. The bright satellite passing by is INSAT-2D, a defunct geostationary satellite.
QinetiQ T6 Performance [34][35]
Type Kaufman Ion Engine
Units on board 4 [36][37]
Diameter Шаблон:Cvt
Max. thrust 145 mN each
Specific impulse
(Isp)
4300 seconds
Propellant Xenon
Total power 4628 W

The Mercury Transfer Module (MTM) has a mass of Шаблон:Cvt, including Шаблон:Cvt of xenon propellant, and is located at the base of the stack. Its role is to carry the two science orbiters to Mercury and to support them during the cruise.

The MTM is equipped with a solar electric propulsion system as the main spacecraft propulsion. Its four QinetiQ-T6 ion thrusters operate singly or in pairs for a maximum combined thrust of 290 mN,[38] making it the most powerful ion engine array ever operated in space. The MTM supplies electrical power for the two hibernating orbiters as well as for its solar electric propulsion system thanks to two Шаблон:Convert solar panels.[39] Depending on the probe's distance to the Sun, the generated power will range between 7 and 14 kW, each T6 requiring between 2.5 and 4.5 kW according to the desired thrust level.

The solar electric propulsion system has typically very high specific impulse and low thrust. This leads to a flight profile with months-long continuous low-thrust braking phases, interrupted by planetary gravity assists, to gradually reduce the velocity of the spacecraft. Moments before Mercury orbit insertion, the MTM will be jettisoned from the spacecraft stack.[39] After separation from the MTM, the MPO will provide Mio all necessary power and data resources until Mio is delivered to its mission orbit; separation of Mio from MPO will be accomplished by spin-ejection.

Mercury Planetary Orbiter

Файл:BepiColombo MPO ESTEC.jpg
Mercury Planetary Orbiter in ESTEC before stacking
Файл:Radio testing of BepiColombo orbiter ESA353568.jpg
Radio testing of BepiColombo orbiter

The Mercury Planetary Orbiter (MPO) has a mass of Шаблон:Cvt and uses a single-sided solar array capable of providing up to 1000 watts and featuring Optical Solar Reflectors to keep its temperature below Шаблон:Cvt. The solar array requires continuous rotation keeping the Sun at a low incidence angle in order to generate adequate power while at the same time limiting the temperature.[39]

The MPO will carry a payload of 11 instruments, comprising cameras, spectrometers (IR, UV, X-ray, γ-ray, neutron), a radiometer, a laser altimeter, a magnetometer, particle analysers, a Ka-band transponder, and an accelerometer. The payload components are mounted on the nadir side of the spacecraft to achieve low detector temperatures, apart from the MERTIS and PHEBUS spectrometers located directly at the main radiator to provide a better field of view.[39]

A high-temperature-resistant Шаблон:Cvt diameter high-gain antenna is mounted on a short boom on the zenith side of the spacecraft. Communications will be on the X-band and Ka-band with an average bit rate of 50 kbit/s and a total data volume of 1550 Gbit/year. ESA's Cebreros, Spain Шаблон:Convert ground station is planned to be the primary ground facility for communications during all mission phases.[39]

Science payload

The science payload of the Mercury Planetary Orbiter consists of eleven instruments:[40][41]

Mio (Mercury Magnetospheric Orbiter)

Файл:BepiColombo MMO ESTEC.jpg
Mio in ESTEC before stacking

Mio, or the Mercury Magnetospheric Orbiter (MMO), developed and built mostly by Japan, has the shape of a short octagonal prism, Шаблон:Cvt long from face to face and Шаблон:Cvt high.[18][47] It has a mass of Шаблон:Cvt, including a Шаблон:Cvt scientific payload consisting of 5 instrument groups, 4 for plasma and dust measuring run by investigators from Japan, and one magnetometer from Austria.[18][48][49]

Mio will be spin stabilized at 15 rpm with the spin axis perpendicular to the equator of Mercury. It will enter a polar orbit at an altitude of Шаблон:Cvt, outside of MPO's orbit.[48] The top and bottom of the octagon act as radiators with louvers for active temperature control. The sides are covered with solar cells which provide 90 watts. Communications with Earth will be through a Шаблон:Cvt diameter X-band phased array high-gain antenna and two medium-gain antennas operating in the X-band. Telemetry will return 160 Gb/year, about 5 kbit/s over the lifetime of the spacecraft, which is expected to be greater than one year. The reaction and control system is based on cold gas thrusters. After its release in Mercury orbit, Mio will be operated by Sagamihara Space Operation Center using Usuda Deep Space CenterШаблон:'s Шаблон:Cvt antenna located in Nagano, Japan.[40]

Science payload

Файл:The search for volcanoes (annotated) ESA24328694.png
Photo captured on 23 June 2022 as the spacecraft flew past the planet for its second of six gravity assist manoeuvres at Mercury. This image was taken by the Mercury Transfer Module’s Monitoring Camera 3, when the spacecraft was 1406 km from the surface of Mercury.

Mio carries five groups of science instruments with a total mass of Шаблон:Cvt:[18][40]

Mercury Surface Element (cancelled)

The Mercury Surface Element (MSE) was cancelled in 2003 due to budgetary constraints.[7] At the time of cancellation, MSE was meant to be a small, Шаблон:Cvt, lander designed to operate for about one week on the surface of Mercury.[22] Shaped as a Шаблон:Cvt diameter disc, it was designed to land at a latitude of 85° near the terminator region. Braking manoeuvres would bring the lander to zero velocity at an altitude of Шаблон:Cvt at which point the propulsion unit would be ejected, airbags inflated, and the module would fall to the surface with a maximum impact velocity of Шаблон:Cvt. Scientific data would be stored onboard and relayed via a cross-dipole UHF antenna to either the MPO or Mio. The MSE would have carried a Шаблон:Cvt payload consisting of an imaging system (a descent camera and a surface camera), a heat flow and physical properties package, an alpha particle X-ray spectrometer, a magnetometer, a seismometer, a soil penetrating device (mole), and a micro-rover.[51]

See also

References

Шаблон:Reflist

External links

Шаблон:Portal bar Шаблон:Mercury (planet) Шаблон:Mercury spacecraft Шаблон:Venus spacecraft Шаблон:ESA projects Шаблон:Japanese space program Шаблон:Planetary Missions Program Office Шаблон:Solar System probes Шаблон:Orbital launches in 2018 Шаблон:2018 in space

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