HOME

TheInfoList



OR:

Europa Clipper (previously known as Europa Multiple Flyby Mission) is an interplanetary mission in development by
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...
comprising an orbiter. Planned for launch in October 2024, the spacecraft is being developed to study the
Galilean moon 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 Jupit ...
Europa Europa may refer to: Places * Europe * Europa (Roman province), a province within the Diocese of Thrace * Europa (Seville Metro), Seville, Spain; a station on the Seville Metro * Europa City, Paris, France; a planned development * Europa Clif ...
through a series of
flybys Flyby may refer to: * Flypast or flyover, a celebratory display or ceremonial flight * Flyby (spaceflight), a spacecraft concept * Planetary flyby, a type of interplanetary spacecraft mission * Gravity assist, a spaceflight maneuver * Fly-by, c ...
while in orbit around
Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousand ...
. This mission is a scheduled flight of the Planetary Science Division, designated a Large Strategic Science Mission, and funded under the Planetary Missions Program Office's Solar System Exploration program as its second flight. It is also supported by the new Ocean Worlds Exploration Program. ''Europa Clipper'' will perform follow-up studies to those made by the ''
Galileo Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He was ...
'' spacecraft during its eight years in Jupiter orbit, which indicated the existence of a subsurface ocean underneath Europa's ice crust. Plans to send a spacecraft to Europa were initially conceived with projects such as '' Europa Orbiter'' and '' Jupiter Icy Moons Orbiter'', in which a spacecraft would be injected into orbit around Europa. However, due to the adverse effects of
radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...
from Jupiter's magnetosphere in Europa orbit, it was decided that it would be safer to inject a spacecraft into an elliptical orbit around Jupiter and make 44 close flybys of the moon instead. The mission began as a joint investigation between the
Jet Propulsion Laboratory The Jet Propulsion Laboratory (JPL) is a Federally funded research and development centers, federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, La Cañada Flintridge, California ...
(JPL) and the Applied Physics Laboratory (APL), and will be built with a scientific payload of nine instruments contributed by JPL, APL,
Southwest Research Institute Southwest Research Institute (SwRI), headquartered in San Antonio, Texas, is an independent and nonprofit applied research and development (R&D) organization. Founded in 1947 by oil businessman Tom Slick, it provides contract research and devel ...
,
University of Texas at Austin The University of Texas at Austin (UT Austin, UT, or Texas) is a public research university in Austin, Texas. It was founded in 1883 and is the oldest institution in the University of Texas System. With 40,916 undergraduate students, 11,075 ...
,
Arizona State University Arizona State University (Arizona State or ASU) is a public research university in the Phoenix metropolitan area. Founded in 1885 by the 13th Arizona Territorial Legislature, ASU is one of the largest public universities by enrollment in the ...
and
University of Colorado Boulder The University of Colorado Boulder (CU Boulder, CU, or Colorado) is a public research university in Boulder, Colorado. Founded in 1876, five months before Colorado became a state, it is the flagship university of the University of Colorado sy ...
. The mission will complement ESA's Jupiter Icy Moons Explorer launching in 2023, which will fly-by Europa twice and Callisto multiple times before moving into orbit around Ganymede. The mission is scheduled to launch in October 2024 aboard a Falcon Heavy, during a 21-day launch window. The spacecraft will use gravity assists from Mars in February 2025 and Earth in December 2026, before arriving at Europa in April 2030.


History

In 1997, a '' Europa Orbiter'' mission was proposed by a team for NASA's Discovery program but was not selected. NASA's JPL announced one month after the selection of Discovery proposals that a NASA Europa orbiter mission would be conducted. JPL then invited the Discovery proposal team to be the Mission Review Committee (MRC). At the same time as the proposal of the Discovery-class ''Europa Orbiter'' the robotic ''
Galileo Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He was ...
'' spacecraft was already orbiting Jupiter. From December 8, 1995, to December 7, 1997 ''Galileo'' conducted the primary mission after entering the orbit of Jupiter. On that final date the Galileo orbiter commenced an extended mission known as the ''Galileo'' Europa Mission (GEM), which ran until December 31, 1999. This was a low-cost mission, with a budget of only US$30 million. The smaller team of about 40–50 people (one-fifth the size of the primary mission's 200-person team from 1995–1997) did not have the resources to deal with problems, but when they arose it was able to temporarily recall former team members (called "tiger teams") for intensive efforts to solve them. The spacecraft made several flybys of
Europa Europa may refer to: Places * Europe * Europa (Roman province), a province within the Diocese of Thrace * Europa (Seville Metro), Seville, Spain; a station on the Seville Metro * Europa City, Paris, France; a planned development * Europa Clif ...
(8), Callisto (4) and Io (2). On each flyby of the three moons it encountered, the spacecraft collected only two days' worth of data instead of the seven it had collected during the primary mission. This ''Galileo'' Europa Mission was similar to a small-scale version of what the ''Europa Clipper'' is planning to accomplish. GEM included eight flybys of Europa, ranging from , in two years. Europa has been identified as one of the locations in the
Solar System The Solar System Capitalization 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 ...
that could possibly harbor microbial
extraterrestrial life Extraterrestrial life, colloquially referred to as alien life, is life that may occur outside Earth and which did not originate on Earth. No extraterrestrial life has yet been conclusively detected, although efforts are underway. Such life might ...
. Immediately following the ''Galileo'' spacecraft's discoveries and the independent Discovery program proposal for a Europa orbiter, JPL conducted preliminary mission studies that envisioned a capable spacecraft such as the Jupiter Icy Moons Orbiter (a US$16 billion mission concept), the Jupiter Europa Orbiter (a US$4.3 billion concept), an orbiter (US$2 billion concept), and a multi-flyby spacecraft: ''Europa Clipper''. A mission to Europa was recommended by the National Research Council in 2013. The approximate cost estimate has rose from US$2 billion in 2013 to US$4.25 billion in 2020. The mission is a joint project between the
Johns Hopkins University Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hemisphere. It consi ...
's Applied Physics Laboratory (APL), and the
Jet Propulsion Laboratory The Jet Propulsion Laboratory (JPL) is a Federally funded research and development centers, federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, La Cañada Flintridge, California ...
(JPL). The mission's name is a reference to the lightweight clipper ships of the 19th century that routinely plied trade routes around the world. The moniker was chosen because the spacecraft will "sail" past Europa, as frequently as every two weeks. In March 2013, US$75 million were authorized to expand on the formulation of mission activities, mature the proposed science goals, and fund preliminary instrument development, as suggested in 2011 by the Planetary Science Decadal Survey. In May 2014, a House bill substantially increased the ''Europa Clipper'' (referred to as ''Europa Multiple Flyby Mission'') funding budget for the 2014 fiscal year from US$15 million to US$100 million to be applied to pre-formulation work. Following the 2014 election cycle, bipartisan support was pledged to continue funding for the ''Europa Multiple Flyby Mission'' project. The executive branch also granted US$30 million for preliminary studies. In April 2015, NASA offered to the
European Space Agency , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (120 ...
to submit concepts for an additional probe to fly together with the ''Europa Clipper'' spacecraft, with a mass limit of 250 kg maximum. It could be a simple probe, an impactor, or a lander. An internal assessment at
European Space Agency , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (120 ...
(ESA) is underway to see if there is interest and funds available,Cassini-Huygens'' approach. In May 2015, NASA chose nine instruments that would fly on board the orbiter, budgeted to cost about US$110 million over the next three years. In June 2015, NASA approved the mission concept, allowing the orbiter to move to its formulation stage, and in January 2016 it approved a lander as well. In May 2016, the Ocean Worlds Exploration Program was approved, of which the Europa mission is part. In February 2017, the mission moved from Phase A to Phase B (the preliminary design phase). On July 18, 2017, the House Space Subcommittee held hearings on the ''Europa Clipper'' as a scheduled Large Strategic Science Missions class, and to discuss a possible follow up mission simply known as the Europa Lander. Phase B continued into 2019. In addition, subsystem vendors were selected, as well as prototype hardware elements for the science instruments. Spacecraft sub-assemblies will be built and tested as well.


Fabrication and assembly

On August 19, 2019, the ''Europa Clipper'' proceeded to Phase C: final design and fabrication. On March 3, 2022, the spacecraft moved on to Phase D: assembly, testing, and launch. On June 7, 2022, the main body of the spacecraft was completed.


Objectives

The goals of ''Europa Clipper'' are to explore Europa, investigate its habitability and aid in the selection of a landing site for the future Europa Lander. This exploration is focused on understanding the three main requirements for life: liquid water,
chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...
, and
energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of ...
. Specifically, the objectives are to study: * Ice shell and ocean: Confirm the existence, and characterize the nature, of water within or beneath the ice, and processes of surface-ice-ocean exchange * Composition: Distribution and chemistry of key compounds and the links to ocean composition * Geology: Characteristics and formation of surface features, including sites of recent or current activity.


Strategy

Because Europa lies well within the harsh radiation fields surrounding Jupiter, even a radiation-hardened spacecraft in near orbit would be functional for just a few months. Most instruments can gather data far faster than the communications system can transmit it to Earth because there are a limited number of antennas available on Earth to receive the scientific data. Therefore, another key limiting factor on science for a Europa orbiter is the time available to return data to Earth. In contrast, the amount of time during which the instruments can make close-up observations is less important. Studies by scientists from the
Jet Propulsion Laboratory The Jet Propulsion Laboratory (JPL) is a Federally funded research and development centers, federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, La Cañada Flintridge, California ...
show that by performing several flybys with many months to return data, the ''Europa Clipper'' concept will enable a US$2 billion mission to conduct the most crucial measurements of the cancelled US$4.3 billion Jupiter Europa Orbiter concept. Between each of the flybys, the spacecraft will have seven to ten days to transmit data stored during each brief encounter. That will let the spacecraft have up to a year of time to transmit its data compared to just 30 days for an orbiter. The result will be almost three times as much data returned to
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...
, while reducing exposure to radiation. The ''Europa Clipper'' will not orbit Europa, but instead orbit
Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousand ...
and conduct 44 flybys of Europa at altitudes from each during its 3.5-year mission. A key feature of the mission concept is that the ''Clipper'' would use gravity assists from
Europa Europa may refer to: Places * Europe * Europa (Roman province), a province within the Diocese of Thrace * Europa (Seville Metro), Seville, Spain; a station on the Seville Metro * Europa City, Paris, France; a planned development * Europa Clif ...
, Ganymede and Callisto to change its trajectory, allowing the spacecraft to return to a different close approach point with each flyby. Each flyby would cover a different sector of Europa in order to achieve a medium-quality global topographic survey, including ice thickness. The ''Europa Clipper'' could conceivably flyby at low altitude through the plumes of water vapor erupting from the moon's ice crust, thus sampling its subsurface ocean without having to land on the surface and drill through the ice. Shielding from Jupiter's harsh radiation belt will be provided by a radiation vault with thick aluminum alloy walls, which will enclose the spacecraft electronics. To maximize the effectiveness of this shielding, the electronics will also be nested in the core of the spacecraft for additional radiation protection.


Design and construction


Power

Both
radioisotope thermoelectric generator A radioisotope thermoelectric generator (RTG, RITEG), sometimes referred to as a radioisotope power system (RPS), is a type of nuclear battery that uses an array of thermocouples to convert the heat released by the decay of a suitable radioa ...
(RTG) and
photovoltaic Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commercially ...
power sources were assessed to power the orbiter.A. Eremenko ''et al.'', "Europa Clipper spacecraft configuration evolution", ''2014 IEEE Aerospace Conference'', pp. 1–13, Big Sky, MT, March 1–8, 2014 Although solar power is only 4% as intense at Jupiter as it is in Earth's orbit, powering a Jupiter orbital spacecraft by
solar panels A solar cell panel, solar electric panel, photo-voltaic (PV) module, PV panel or solar panel is an assembly of photovoltaic solar cells mounted in a (usually rectangular) frame, and a neatly organised collection of PV panels is called a photo ...
was demonstrated by the ''Juno'' mission. The alternative to solar panels was a
multi-mission radioisotope thermoelectric generator The multi-mission radioisotope thermoelectric generator (MMRTG) is a type of radioisotope thermoelectric generator (RTG) developed for NASA space missions such as the Mars Science Laboratory (MSL), under the jurisdiction of the United States Depa ...
(MMRTG), fueled with
plutonium-238 Plutonium-238 (238Pu or Pu-238) is a fissile, radioactive isotope of plutonium that has a half-life of 87.7 years. Plutonium-238 is a very powerful alpha emitter; as alpha particles are easily blocked, this makes the plutonium-238 isotope suit ...
. The power source has already been demonstrated in the Mars Science Laboratory (MSL) mission. Five units were available, with one reserved for the Mars 2020 rover mission and another as backup. In September 2013, it was decided that the solar array was the less expensive option to power the spacecraft, and on October 3, 2014, it was announced that solar panels were chosen to power ''Europa Clipper''. The mission's designers determined that solar power was both cheaper than plutonium and practical to use on the spacecraft. Despite the increased weight of solar panels compared to plutonium-powered generators, the vehicle's mass had been projected to still be within acceptable launch limits. Initial analysis suggest that each panel will have a surface area of and produce 150 watts continuously when pointed towards the Sun while orbiting Jupiter. While in Europa's shadow, batteries will enable the spacecraft to continue gathering data. However,
ionizing radiation Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...
can damage solar panels. The ''Europa Clipper'' orbit will pass through Jupiter's intense magnetosphere, which is expected to gradually degrade the solar panels as the mission progresses. The solar panels will be provided by
Airbus Defence and Space Airbus Defence and Space is the division of Airbus SE responsible for the development and manufacturing of the corporation's defence and space products, while also providing related services. The division was formed in January 2014 during the ...
,
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
.


Scientific payload

The ''Europa Clipper'' mission is equipped with a sophisticated suite of 9 instruments to study Europa's interior and
ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wor ...
,
geology Geology () is a branch of natural science concerned with Earth and other Astronomical object, astronomical objects, the features or rock (geology), rocks of which it is composed, and the processes by which they change over time. Modern geology ...
,
chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...
, and habitability. The electronic components will be protected from the intense radiation by a 150-kilogram
titanium Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion i ...
and aluminum shield. The spacecraft payload and trajectory are subject to change as the mission design matures. The nine science instruments for the orbiter, announced in May 2015, have an estimated total mass of and are listed below:


Europa Thermal Emission Imaging System (E-THEMIS)

The Europa Thermal Emission Imaging System will provide high spatial resolution as well as multi-spectral imaging of the surface of Europa in the mid to far infrared bands to help detect geologically active sites and areas, such as potential vents erupting plumes of water into space. This instrument is derived from the
Thermal Emission Imaging System The Thermal Emission Imaging System (THEMIS) is a camera on board the 2001 Mars Odyssey orbiter. It images Mars in the visible and infrared parts of the electromagnetic spectrum in order to determine the thermal properties of the surface and ...
(THEMIS) on the '' 2001 Mars Odyssey'' orbiter, also developed by Philip Christensen. *


Mapping Imaging Spectrometer for Europa (MISE)

The Mapping Imaging Spectrometer for Europa is an imaging near infrared spectrometer to probe the surface composition of Europa, identifying and mapping the distributions of organics (including
amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
s and tholins ), salts, acid hydrates, water ice phases, and other materials. From these measurements, scientists expect to be able to relate the moon's surface composition to the habitability of its ocean. MISE is built in collaboration with the Johns Hopkins University Applied Physics Laboratory (APL). *


Europa Imaging System (EIS)

The Europa Imaging System is a
visible spectrum The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called '' visible light'' or simply light. A typical human eye will respond to ...
wide and narrow angle camera instrument that will map most of Europa at resolution, and will provide images of selected surface areas at up to resolution. *


Europa Ultraviolet Spectrograph (Europa-UVS)

The Europa Ultraviolet Spectrograph instrument will be able to detect small plumes and will provide valuable data about the composition and dynamics of the moon's
exosphere The exosphere ( grc, ἔξω "outside, external, beyond", grc, σφαῖρα "sphere") is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the densi ...
. The principal investigator Kurt Retherford was part of a group that discovered plumes erupting from Europa while using the
Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most vers ...
in the
UV spectrum Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30  PHz) to 400 nm (750  THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
. *


Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON)

The Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) is a dual-frequency ice penetrating radar instrument that is designed to characterize and sound Europa's ice crust from the near-surface to the ocean, revealing the hidden structure of Europa's ice shell and potential water pockets within. This instrument will be built by
Jet Propulsion Laboratory The Jet Propulsion Laboratory (JPL) is a Federally funded research and development centers, federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, La Cañada Flintridge, California ...
. *


Interior Characterization of Europa using Magnetometry (ICEMAG)

The Interior Characterization of Europa using Magnetometry (ICEMAG) was cancelled due to cost overruns. ICEMAG will be replaced by a simpler magnetometer.


Europa Clipper Magnetometer (ECM)

Replacing the ICEMAG instrument, Europa Clipper Magnetometer (ECM) will be used to characterize the magnetic fields around Europa. The instrument consists of three magnetic flux gates placed along a 25ft boom, which will be stowed during launch and deployed afterwards. By studying the strength and orientation of Europa's magnetic field over multiple flybys, scientists hope to be able to confirm the existence of Europa's subsurface ocean, as well as characterize the thickness of its icy crust and measure the water's depth and salinity. *


Plasma Instrument for Magnetic Sounding (PIMS)

The Plasma Instrument for Magnetic Sounding (PIMS) measures the plasma surrounding Europa to characterise the magnetic fields generated by plasma currents. These plasma currents mask the magnetic induction response of Europa's subsurface ocean. In conjunction with a magnetometer, it is key to determining Europa's ice shell thickness, ocean depth, and salinity. PIMS will also probe the mechanisms responsible for weathering and releasing material from Europa's surface into the
atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A ...
and
ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays ...
and understanding how Europa influences its local space environment and Jupiter's
magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior d ...
. *


Mass Spectrometer for Planetary Exploration (MASPEX)

The Mass Spectrometer for Planetary Exploration (MASPEX) will determine the composition of the surface and subsurface ocean by measuring Europa's extremely tenuous atmosphere and any surface materials ejected into space. Jack Waite, who led development of MASPEX, was also Science Team Lead of the Ion and Neutral Mass Spectrometer (INMS) on the '' Cassini'' spacecraft. *


Surface Dust Analyzer (SUDA)

The SUrface Dust Analyzer (SUDA) is a mass spectrometer that will measure the composition of small solid particles ejected from Europa, providing the opportunity to directly sample the surface and potential plumes on low-altitude flybys. The instrument is capable of identifying traces of organic and inorganic compounds in the ice of ejecta. *


Gravity/Radio Science

While not intended for use specifically as an instrument, Clipper will be using its radio antenna to perform additional experiments and learn about Europa's gravitational field. As the spacecraft performs each of its 45 flybys, its trajectory will be subtly altered by the moon's gravity. By sending radio signals between earth and the moon and characterizing the
Doppler Shift The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who ...
in the return signal, scientists at JPL will be able to create a detailed characterization of the spacecraft's motion. This data will help to determine how the moon is flexing in relation to its distance from Jupiter, which will in turn reveal information about the moon's internal structure and tidal motions. *


Proposed secondary elements

The ''Europa Clipper'' mission considered an extra mass of about to carry an additional flight element. About a dozen proposals have been suggested but none went beyond the concept study phase and none are planned for the Europa Clipper mission. A few of which are described next:


Nanosatellites

Since the ''Europa Clipper'' mission may not be able to easily modify its orbital trajectory or altitude to fly through the episodic water plumes, scientists and engineers working on the mission have investigated deploying from the spacecraft several miniaturized satellites of the CubeSat format, possibly driven by ion thrusters, to fly through the plumes and assess the habitability of Europa's internal ocean. Some early proposals include ''Mini-MAGGIE'', ''DARCSIDE'', ''Sylph'' and CSALT. These concepts were funded for preliminary studies but none were considered for hardware development or flight. The ''Europa Clipper'' would have relayed signals from the nanosatellites back to
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...
. With propulsion, some nanosatellites could also be capable of entering orbit around Europa.


Secondary orbiters


= Biosignature Explorer for Europa

= NASA was also assessing the release of an additional probe called ''Biosignature Explorer for Europa'' (BEE), that would have been equipped with a basic bi-propellant engine and cold gas thrusters to be more agile and responsive to the episodic activity on Europa and sample and analyze the water plumes for
biosignature A biosignature (sometimes called chemical fossil or molecular fossil) is any substance – such as an element, isotope, or molecule – or phenomenon that provides scientific evidence of past or present life. Measurable attribute ...
s and life evidence before they are destroyed by radiation. The BEE plume probe would have been equipped with a proven mass spectrometer combined with
gas chromatograph Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substan ...
separation. It would also carry an
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30  PHz) to 400 nm (750  THz), shorter than that of visible light, but longer than X-rays. UV radiation ...
(UV) plume targeting camera as well as visible and
infrared camera Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
s to image the active region with better resolution than the ''Clipper'' mother ship instruments. The BEE probe would have flown through at altitude, then made a quick exit and performed its analysis far from the radiation belts.


= Europa Tomography Probe

= A European proposal, the Europa Tomography Probe, was a concept for an independent powered spacecraft equipped with a
magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, ...
that would orbit Europa on a polar orbit for at least six months. It would have determined the deep interior structure of Europa and provided a good determination of the ice shell thickness and ocean depth, which arguably cannot be done accurately by multiple flybys.


Impactor probes

Some proposed impactor probe concepts include those by the
Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...
, and
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...
.


Flyby sample return

The ''Europa Life Signature Assayer'' (ELSA) concept by the
University of Colorado The University of Colorado (CU) is a system of public universities in Colorado. It consists of four institutions: University of Colorado Boulder, University of Colorado Colorado Springs, University of Colorado Denver, and the University o ...
consisted of a probe that could have been flown as a secondary payload. ELSA would have used a small impactor to create a plume of subsurface particles and catapulted them to altitudes where it would have been able to pass through to collect samples and analyze them on board. A variation of this concept is the 1996 ''Ice Clipper'', which involves a impactor that would be jettisoned from the main spacecraft to impact Europa, thereby creating a debris cloud in nearby space about altitude, subsequently sampled by a small spacecraft on a close flyby and use Europa's gravitational force for a free return trajectory.).


Add-on lander history

An early ''Europa Clipper'' concept called for including a stationary lander about in diameter, perhaps about with a maximum of for instruments plus propellant. Suggested instruments were a mass spectrometer and a Raman spectrometer to determine the chemistry of the surface. The lander was proposed to be delivered to Europa by the main spacecraft and possibly require the sky crane system for a high precision, soft landing near an active crevasse. The lander would have operated about 10 days on the surface using battery power. The ''Europa Clipper'' would take about three years to image 95% of the surface of Europa at about per pixel. With this data, scientists could then find a suitable landing site. By one estimate, including a lander could add as much as US$1 billion to the mission's cost.


Separate launch

It was determined in February 2017 that designing a system capable of landing on a surface about which very little is known bears too much risk, and that the ''Europa Clipper'' will lay the foundation for a future landing mission by performing detailed reconnaissance first. This led to a stand-alone mission proposal in 2017: the Europa Lander. The NASA Europa Lander, if funded, would be launched separately in 2025 to complement the studies by the ''Europa Clipper'' mission. Space Launch System The Space Launch System (SLS) is an American super heavy-lift expendable launch vehicle developed by NASA. As of 2022, SLS has the highest payload capacity of any rocket in operational service, as well as the greatest liftoff thrust of any ...
(SLS)
super heavy-lift launch vehicle A super heavy-lift launch vehicle can lift to low Earth orbit more than by United States (NASA) classification or by Russian classification. It is the most capable launch vehicle classification by mass to orbit, exceeding that of the heavy-lif ...
, but
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...
had requested that other vehicles be allowed to launch the spacecraft due to a foreseen lack of available SLS vehicles. The United States Congress's 2021 omnibus spending bill directed the NASA Administrator to conduct a full and open competition to select a commercial launch vehicle if the conditions to launch the probe on a SLS rocket cannot be met. A launch on a Delta IV Heavy with a gravity assist at Venus was considered. On January 25, 2021, NASA's Planetary Missions Program Office formally directed the mission team to "immediately cease efforts to maintain SLS compatibility" and move forward with a commercial launch vehicle. On February 10, 2021, it was announced that the mission would use a 5.5-year trajectory to the Jovian system, with gravity-assist maneuvers involving Mars (February 2025) and Earth (December 2026). Launch is targeted for a 21-day period between October 10 and 30, 2024, giving an arrival date in April 2030, and backup launch dates were identified in 2025 and 2026. The SLS option would have entailed a direct trajectory to Jupiter taking less than three years. One alternative to the direct trajectory was identified as using a commercial rocket such as a Falcon Heavy, with a longer 6-year cruise time involving gravity assist maneuvers at
Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...
,
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...
and/or
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
. Another option was to launch on a Falcon Heavy and perform a maneuver at insertion orbit aphelion. This launch window is open once a year and would have required only one gravity assist, with Earth, and would shorten the travel time to 4.5 years, while only needing a C3 of 25–28 km2/s2. In July 2021 Falcon Heavy was chosen to launch the spacecraft. Three reasons were given: launch cost, SLS availability, and "shaking". The move to Falcon Heavy saved an estimated US$2 billion in launch costs alone. NASA was not sure an SLS would be available since the Artemis program would use the entire SLS production, and the SLS's use of
solid rocket booster A solid rocket booster (SRB) is a large solid propellant motor used to provide thrust in spacecraft launches from initial launch through the first ascent. Many launch vehicles, including the Atlas V, SLS and space shuttle, have used SRBs to gi ...
s (SRB)s intrinsically creates more vibrations in the payload than does a launcher that does not use SRBs. The cost to redesign Europa Clipper for the SLS vibratory environment was estimated at US$1 billion.


See also

* * * * * * *


References


External links

*
''Europa'' Mission
a
NASA's Solar System Exploration
{{Future spaceflights Proposed NASA space probes Proposed astrobiology space missions NASA programs 2024 in spaceflight Missions to Jupiter Orbiters (space probe) Europa (moon) Solar System Exploration program