Tianwen-4
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''Tianwen-4'' is a planned interplanetary mission by China to study the
Jovian Jovian is the adjectival form of Jupiter and may refer to: * Jovian (emperor) (Flavius Iovianus Augustus), Roman emperor (363–364 AD) * Jovians and Herculians, Roman imperial guard corps * Jovian (lemur), a Coquerel's sifaka known for ''Zoboomafo ...
system and its environs, sharing a launch with a spacecraft which will make a flyby of
Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus (mythology), Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars (mythology), Mars), grandfather ...
. Prior to its naming as ''Tianwen-4'', the mission was known as ''Gan De''.


Overview

The goals of the planned ''Tianwen-4'' Jupiter mission were detailed in an article published in a Chinese academic journal, they include the following: study of the interaction between magnetic fields and plasma present in the Jovian system, examination of the compositional variations in the Jovian atmosphere, exploration of the internal structures and surface characteristics of either Ganymede or
Callisto Callisto most commonly refers to: *Callisto (mythology), a nymph *Callisto (moon), a moon of Jupiter Callisto may also refer to: Art and entertainment *''Callisto series'', a sequence of novels by Lin Carter *''Callisto'', a novel by Torsten Kro ...
, as well as investigation of the space environment surrounding the aforementioned
Galilean satellites The Galilean moons (), or Galilean satellites, are the four largest moons of Jupiter: Io, Europa, Ganymede, and Callisto. They were first seen by Galileo Galilei in December 1609 or January 1610, and recognized by him as satellites of Jupiter ...
. According to reports in the Western media, there are two competing mission profiles as of January 2021: the 'Jupiter Callisto Orbiter' (JCO) and the 'Jupiter System Observer' (JSO). 'JCO' would involve a spacecraft conducting fly-bys of Jupiter's
irregular satellites In astronomy, an irregular moon, irregular satellite or irregular natural satellite is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit. They have been captured by their parent planet, unlike regular sat ...
before it enters into a polar orbit about
Callisto Callisto most commonly refers to: *Callisto (mythology), a nymph *Callisto (moon), a moon of Jupiter Callisto may also refer to: Art and entertainment *''Callisto series'', a sequence of novels by Lin Carter *''Callisto'', a novel by Torsten Kro ...
; this mission profile also may include a Callisto lander. In contrast, the 'JSO' mission profile, while broadly similar to that of 'JCO', would forgo an attempt by a spacecraft to orbit Callisto and instead would focus on more intensive studies of the Galilean moon Io (the 'JSO' mission profile also does not appear to include a lander though it may involve sending the spacecraft to the Sun-Jupiter L1 point at the conclusion of its tour of the Jovian system). Finally, presentations by Chinese researchers suggest that the ''Tianwen-4'' Jupiter mission may include an additional probe that would conduct a fly-by of
Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus (mythology), Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars (mythology), Mars), grandfather ...
sometime after 2040. The original name of this mission referenced the fourth century BCE Chinese astronomer
Gan De Gan De (; fl. 4th century BC), also known as the Lord Gan (Gan Gong), was an ancient Chinese astronomer and astrologer born in the State of Qi. Along with Shi Shen, he is believed to be the first in history known by name to compile a star catalo ...
, who made early planetary observations and reputedly first observed the
Galilean moons The Galilean moons (), or Galilean satellites, are the four largest moons of Jupiter: Io, Europa, Ganymede, and Callisto. They were first seen by Galileo Galilei in December 1609 or January 1610, and recognized by him as satellites of Jupiter ...
with the unaided eye.


Background

On October 15, 2003,
CNSA China National Space Administration (CNSA; ) is the government agency of the People's Republic of China that is responsible for civil space administration and international space cooperation, including organizing or leading foreign exchanges ...
launched China's first independent crewed orbital mission; subsequently it prosecuted successful robotic lunar orbital missions (
Chang'e 1 Chang'e 1 (; ) was an unmanned Chinese lunar-orbiting spacecraft, part of the first phase of the Chinese Lunar Exploration Program. The spacecraft was named after the Chinese Moon goddess, Chang'e. Chang'e 1 was launched on 24 October 2007 at 10 ...
and
Chang'e 2 Chang'e 2 (; ) is a Chinese unmanned lunar probe that was launched on 1 October 2010. It was a follow-up to the Chang'e 1 lunar probe, which was launched in 2007. Chang'e 2 was part of the first phase of the Chinese Lunar Exploration Program, and ...
) and a robotic lunar lander/rover mission (
Chang'e 3 Chang'e 3 (; ) is a robotic lunar exploration mission operated by the China National Space Administration (CNSA), incorporating a robotic lander and China's first lunar rover. It was launched in December 2013 as part of the second phase of ...
). In the hope of building upon these achievements, CNSA began to contemplate more ambitious interplanetary missions in the 2020s and beyond. In 2018, Pei Zhaoyu, the deputy director of
CNSA China National Space Administration (CNSA; ) is the government agency of the People's Republic of China that is responsible for civil space administration and international space cooperation, including organizing or leading foreign exchanges ...
's Lunar Exploration and Space Program Center stated that China was planning to conduct four major interplanetary missions before the end of the 2020s; the four missions include a mission to
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
(
Tianwen-1 -1 (TW-1; zh, t=, s=, l='Heavenly Questions') is an interplanetary mission by the China National Space Administration (CNSA) which sent a robotic spacecraft to Mars, consisting of 6 spacecraft: an orbiter, two deployable cameras, lander, rem ...
), a
main-belt comet Active asteroids are small Solar System bodies that have asteroid-like orbits but show comet-like visual characteristics. That is, they show comae, tails, or other visual evidence of mass-loss (like a comet), but their orbit remains within Jup ...
and asteroid sample-return mission (
Tianwen-2 ''Tianwen-2'', formerly known as ''ZhengHe'', is a planned Chinese asteroid sample-return and comet exploration mission that is currently under development. Overview ''Tianwen-2'' is planned to be launched by a Long March 3B rocket around 20 ...
), a Mars sample-return mission (Tianwen-3), and a Jupiter system mission. As of early 2021, the aforementioned JCO and JSO mission profiles are competing to be realized as the ''Tianwen-4'' Jupiter system mission.


Possible mission timeline

One possible Earth-Jupiter mission trajectory and timeline was presented at the 2020 General Assembly meetings of the EGU. Under this scenario, the Tianwen-4 probe would launch in October 2029, conduct a Venus fly-by six months later in April 2030, then proceed to encounter Earth twice (the first encounter occurring in February 2031 and the second in May 2033), with a Jupiter arrival in August 2035 for a total transit time of 5.87 years.


Mission architecture

As of 2021, one of the two following mission profiles (JCO and JSO) is likely to resemble the final mission architecture:


Jupiter Callisto Orbiter (JCO)

JCO would fly by several irregular Jovian satellites before entering a polar orbit around
Callisto Callisto most commonly refers to: *Callisto (mythology), a nymph *Callisto (moon), a moon of Jupiter Callisto may also refer to: Art and entertainment *''Callisto series'', a sequence of novels by Lin Carter *''Callisto'', a novel by Torsten Kro ...
. This scenario includes a possible lander which, like the Chang’e lunar landers, would provide unprecedented insights into the moon's formation and evolution. Callisto is the outermost of the four Galilean moons. Its interior experiences less heating due to gravity from the other moons and Jupiter. It likely formed with leftover Jupiter material and has sat mostly dormant since, with only asteroid impacts to modify its surface. The moon thus preserves a history of the early Jupiter system and the
Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
at large for a lander to study. Callisto also has a thin atmosphere with small amounts of oxygen, increasing its scientific allure despite being less glamorous than fellow subsurface ocean moons Europa and Ganymede and volatile, active Io. Callisto is also the least challenging Jovian moon to land on. A spacecraft requires less fuel to reach it, and it sits outside Jupiter's intense radiation field. These are rationales that argue for Callisto as the main mission target. JCO also includes a secondary spacecraft that would independently fly towards and encounter with
Uranus Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus (mythology), Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars (mythology), Mars), grandfather ...
sometime in the late 2040s.


Jupiter Systems Observer (JSO)

JSO would substitute a possible Callisto landing with an in-depth investigation of the Jovian moon Io. The spacecraft would perform several Io flybys, studying how Jupiter's gravity tugs on the moon to power its volcanic activity. JSO would also study the mass, density, dynamics and chemical and isotopic composition of irregular satellites and would provide insights into these unique remnants of Jupiter's formation. As an option, JSO could release one or several small satellites to perform multi-point studies of the dynamics of the Jovian magnetosphere. At the end of its tour JSO could be sent to orbit the Sun-Jupiter L1 point, where the planet's gravity balances with the Sun's in a way that spacecraft can remain there for long periods of time. From this unique perch where no spacecraft has ever visited, JSO could monitor the solar wind outside of Jupiter's magnetic field, and survey the irregular Jovian moons from afar.


Mission instruments

Potential scientific instruments for the Tianwen-4 mission were discussed during a session of the 2020 General Assembly of the
European Geosciences Union The European Geosciences Union (EGU) is a non-profit international union in the fields of Earth, planetary, and space sciences whose vision is to "realise a sustainable and just future for humanity and for the planet." The organisation has headq ...
that took place in May 2020. The possible instruments were categorized into four payload packages designed to address the two main goals of the mission: answering questions on the formation and current "workings" of the Jovian system (the actual instruments selected would depend on whether JCO or JSO is selected as the mission profile.) The four payload packages are: (A) plasma and dust analyzers, (B) multi-wavelength spectroscopic instruments, (C) geology/glaciology/geochemistry analyzers, and (D) radio/optical links and radio science instruments.


Plasma and dust analyzers package

* Thermal plasma spectrometer (100 eV to 100 keV) * High-energy charged particle detector and
energetic neutral atom Energetic Neutral Atom (ENA) imaging, often described as "seeing with atoms", is a technology used to create global images of otherwise invisible phenomena in the magnetospheres of planets and throughout the heliosphere. The solar wind is com ...
(ENA) analyzer * Ion and neutral mass spectrometer * Magnetometer * Radio and plasma wave spectrometer * Cosmic dust detector with mass spectrometer


Multi-wavelength imaging/spectroscopy package

* Visible-wavelength imaging camera * Near-infrared imager/spectrometer * Far-infrared/submillimeter wave radiometer/spectrometer * Ultra-violet imager/spectrometer


Geology/glaciology/geochemistry analyzers package

* High-mass resolution and large mass range mass spectrometer (fed-by sampling system for ice surface and by pyrolyser or refractory component


Radio + optical link + radio science package

* Transmission/reception radio link to Earth for Doppler tracking and occultation measurements * Inter-platform radio links for additional Doppler tracking and occultation measurements * "PRIDE" astrometry experiment (
Very-long-baseline interferometry Very-long-baseline interferometry (VLBI) is a type of astronomical interferometer, astronomical interferometry used in radio astronomy. In VLBI a signal from an astronomical radio source, such as a quasar, is collected at multiple radio telesco ...
tracking of each flight element) * Altimeter (with meter-level accuracy)


Notes


References


External links

{{Portal bar, Astronomy, Space, Spaceflight, Solar System, China Chinese space probes 2029 in spaceflight 2029 in China Missions to Jupiter Missions to Uranus Proposed space probes