REX or Radio Science Experiment is an experiment on the ''

New Horizons ''New Horizons'' is an Interplanetary spaceflight, 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 Institut ...

'' space probe to measure properties of the atmosphere of Pluto during the 2015 flyby.

Experiment

Experiment was designed with several goals including determination of pressure and temperature of Plutonian atmosphere, measurements of a possible

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 ...

of Pluto and

Charon In Greek mythology, Charon or Kharon ( ; ) is a psychopomp, the ferryman of the Greek underworld. He carries the souls of those who have been given funeral rites across the rivers Acheron and Styx, which separate the worlds of the living and ...

, recording thermal emission temperatures, and taking more accurate chord lengths of Charon and Pluto. To accomplish the goals, as the spacecraft passed by Pluto, it was placed on a path that took it behind the dwarf planet in relation to the Earth, where radio signals from the flyby spacecraft passed through its atmosphere allowing various properties to be determined. REX also took measurements of the atmospheric conditions at Pluto's moon Charon as part of the mission. REX uses an ultrastable oscillator, various electronics, and radio hardware aboard the New Horizons spacecraft. REX uses the X-band radio uplink on the spacecraft. REX hardware weighs 160g (0.16 kg) and consumes 1.6 watts of spacecraft electrical power. It also makes use of other NH hardware, overall key hardware components for REX include: * high-gain antenna * low-noise

X-band The X band is the designation for a band of frequency, frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is set at approximately 7.0� ...

receiver * ultrastable oscillator To take the measurements, REX communicates with the

Deep Space Network The NASA Deep Space Network (DSN) is a worldwide Telecommunications network, network of spacecraft communication ground segment facilities, located in the United States (California), Spain (Madrid), and Australia (Canberra), that supports NASA' ...

on Earth. Observation goals: *temperature profiles of Pluto's atmosphere *pressure profiles of Pluto's atmosphere *radiometric temperature *gravitational moments *ionosphere structure

Extended mission

REX is also being used in the ''New Horizon''s post Pluto extended mission, including the

486958 Arrokoth 486958 Arrokoth (Provisional designation in astronomy, provisional designation ; formerly nicknamed Ultima Thule) is a trans-Neptunian object located in the Kuiper belt. Arrokoth became the farthest and most primitive List of minor planet ...

flyby. REX is being used to take thermal measurements of the Kuiper belt body during the flyby. REX is also used to study the amount of electrons in outer space in the

Kuiper belt The Kuiper belt ( ) is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...

region. The Kuiper belt is a ring of orbiting bodies between approximately 30 to 55 AU (Earth-Sun distances), home to Pluto and short-period comets it is estimated to consist of hundreds of thousand if not millions of small icy objects. The belt was discovered in 1992, and can be studied more closely by the New Horizons mission which passed through it in the late 2010s. During the post Pluto cruise, REX is normally turned on monthly to measure the electron density of the solar wind between Earth and the spacecraft. When ''New Horizons'' flew by Pluto in 2015, it was at about 32.9 AU from the Sun, and about 43.6 AU for the New Year's Day 2019 flyby of Arrokoth. The timing of the Arrokoth flyby was adjusted in part to aid the use of the REX experiment, so that more radar dishes on Earth could be used.

Data from REX

Using REX radio occultation data the diameter of Pluto was found to be in a 2017 paper.

References

External links

NASA - REX
{{NH1 New Horizons Spacecraft instruments

Experiment

Extended mission

Data from REX

See also

References

External links