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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Europa Clipper | 3/6 | https://en.wikipedia.org/wiki/Europa_Clipper | reference | science, encyclopedia | 2026-05-05T13:18:31.671242+00:00 | kb-cron |
=== Power === Both radioisotope thermoelectric generator (RTG) and photovoltaic power sources were assessed as options to power the orbiter. Although solar power is only 4% as intense at Jupiter as it is in Earth's orbit, powering a Jupiter orbital spacecraft with solar panels was demonstrated by the Juno mission. The alternative to solar panels was a multi-mission radioisotope thermoelectric generator (MMRTG), fueled with plutonium-238. The power source had 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 was projected to still be within acceptable launch limits. Each panel has a surface area of 18 m2 (190 sq ft) and produces 150 watts continuously when pointed towards the Sun while orbiting Jupiter. When in Europa's shadow, onboard batteries charged by the solar panels will enable the spacecraft to continue gathering data. However, ionizing radiation can damage solar panels. The Europa Clipper's orbit will pass through Jupiter's intense magnetosphere, which is expected to gradually degrade the solar panels as the mission progresses. The solar panels were provided by Airbus Defence and Space, Netherlands.
=== Propulsion === The propulsion subsystem was built by NASA's Goddard Space Flight Center in Greenbelt, Maryland. It is part of the Propulsion Module, delivered by Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. It is 3 meters (10 ft) tall, 1.5 meters (5 ft) in diameter and comprises about two-thirds of the spacecraft's main body. The propulsion subsystem carries nearly 2,700 kilograms (6,000 lb) of monomethyl hydrazine and dinitrogen tetroxide propellant, 50% to 60% of which will be used for the 6-to-8-hour Jupiter orbit insertion burn. The spacecraft has a total of 24 rocket engines rated at 27.5 N (6.2 lbf) thrust for attitude control and propulsion.
=== Communication ===
The spacecraft includes a suite of antennas for communication and scientific measurements. Chief among them is the high-gain antenna (HGA), which is 3.1 meters (10 feet) in diameter and is capable of both uplink and downlink communications over multiple frequency bands. The HGA operates on X-band frequencies of 7.2 GHz (uplink) and 8.4 GHz (downlink), as well as a Ka-band frequency of 32 GHz, approximately 12 times higher than typical cellular communications. The communication system includes additional antennas such as low-gain antennas (LGAs), medium-gain antennas (MGAs), and fan-beam antennas (FBAs), which are used for different mission phases depending on orientation and distance from Earth. The Ka-band is primarily used for high-rate data return, enabling faster transmission of scientific data. Data rates vary depending on antenna alignment, frequency, and ground station availability. Downlink data rates via X-band can reach approximately 16 kilobits per second, while Ka-band transmissions can reach up to 500 kilobits per second under optimal conditions. Uplink rates for command transmission are typically around 2 kilobits per second. The antenna system supports not only communications but also radio science and gravity science experiments. Using coherent two-way X-band Doppler tracking and radio occultation techniques, researchers will study Europa's internal structure, ice shell thickness, ocean characteristics, and gravity field. Small variations in the spacecraft's velocity—detected via Doppler shifts—will help scientists determine the moon's mass distribution and potential subsurface ocean. The HGA was designed and developed under the leadership of Matt Bray at the Johns Hopkins Applied Physics Laboratory (APL), and underwent rigorous testing at Langley Research Center and Goddard Space Flight Center in 2022, including beam pattern, thermal vacuum, and vibration testing to ensure precision and reliability.
=== Scientific equipment === The Europa Clipper mission is equipped with nine scientific instruments. The nine science instruments for the orbiter, announced in May 2015, have a planned total mass of 82 kg (181 lb).
==== 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 heat which would suggest geologically active sites and areas, such as potential vents erupting plumes of water into space. The principal investigator is Philip Christensen of Arizona State University. This instrument is derived from the Thermal Emission Imaging System (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 acids and tholins), salts, acid hydrates, water ice phases, and other materials. The principal investigator is Diana Blaney of Jet Propulsion Laboratory and the instrument was built in collaboration with the Johns Hopkins University Applied Physics Laboratory (APL).
==== Europa Imaging System (EIS) ==== The Europa Imaging System consists of visible spectrum cameras to map Europa's surface and study smaller areas in high resolution, as low as 0.5 m (20 in) per pixel. It consists of two cameras, both of which use 2048x4096 pixel CMOS detectors: