Rotation and Interior Structure Experiment (RISE) is a radio science experiment onboard ''

InSight Insight is the understanding of a specific cause and effect within a particular context. The term insight can have several related meanings: *a piece of information *the act or result of understanding the inner nature of things or of seeing intu ...

'' Mars lander that will use the spacecraft communication system to provide precise measurements of

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 atmos ...

' rotation and wobble. RISE precisely tracks the location of the lander to measure how much Mars's axis wobbles as it orbits the Sun. These observations will provide new constraints on the core radius and help determine whether the core of Mars is mostly liquid, and which other elements, besides iron, may be present. This study will also help scientists understand why Mars's magnetic field is so weak, as compared to Earth's. The mission launched on 5 May 2018 and landed on the surface of Mars at Elysium Planitia on 26 November 2018.

Overview

PIA19664-MarsInSightLander-Assembly-20150430

The Principal Investigator for RISE is William Folkner of JPL, who led the 1997 investigation of Mars's core using the radio link between Earth and NASA's

Mars Pathfinder ''Mars Pathfinder'' (''MESUR Pathfinder'') is an American robotic spacecraft that landed a base station with a roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight, wheeled roboti ...

. RISE uses the spacecraft's radio connection with Earth to assess perturbations of Mars's rotation axis to within 10 centimeters.Mars InSight Landing Press Kit
(PDF) NASA. Published: November 2018.NASA's InSight Passes Halfway to Mars, Instruments Check In.
D. C. Agle, ''NASA News''. 20 August 2018. These measurements can provide information about the size and composition of Mars's core.The Rotation and Interior Structure Experiment on the InSight Mission to Mars.
William M. Folkner, Véronique Dehant, Sébastien Le Maistre, Marie Yseboodt, Attilio Rivoldini, Tim Van Hoolst, Sami W. Asmar, Matthew P. Golombek. ''Space Science Reviews'', 9 August 2018, 214:100. Online The radio science equipment is largely the same as used for the

Mars Exploration Rover NASA's Mars Exploration Rover (MER) mission was a robotic space mission involving two Mars rovers, '' Spirit'' and '' Opportunity'', exploring the planet Mars. It began in 2003 with the launch of the two rovers to explore the Martian surface ...

mission, and it includes two medium-

gain Gain or GAIN may refer to: Science and technology * Gain (electronics), an electronics and signal processing term * Antenna gain * Gain (laser), the amplification involved in laser emission * Gain (projection screens) * Information gain in d ...

horn antenna A horn antenna or microwave horn is an antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are widely used as antennas at UHF and microwave frequencies, above 300 MHz. They are ...

s (MGAs) on the lander deck, and an

X band The X band is the designation for a band of 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 rather indefinitely set at approxi ...

radio

transponder In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a flight trans ...

(8 GHz) and transmitter inside the lander, where electronics can be shielded from the harsh conditions of space.The Rotation and Interior Structure Experiment (RISE) for the InSight mission to Mars.
(PDF) W. M. Folkner, S. W. Asmar, V. Dehant and R. W. Warwick. 43rd Lunar and Planetary Science Conference. 2012. Although the lander will communicate all other science data in

UHF Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (on ...

to relay orbiters, the X band can be used directly with Earth in case of some problems with relay through an orbiter. In principle, after ''

'' lands on Mars, the lander reflects a signal sent from Earth, revealing its exact location and velocity in space.Mars InSight Mission - RISE
NASA/JPL. Accessed: 12 November 2018. In doing so, the experiment measures changes in the signal, known as the

Doppler effect 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, ...

as Mars -and the lander on it- move around the Sun. Scientists can use this information to understand how much Mars wobbles in its orbit, which relates to the nature of its iron-rich core. A planet with a liquid core will wobble more as it spins, compared to one that is solid at its core. The sensitivity is such that RISE can also detect the rotation changes caused by the seasonal redistribution of carbon dioxide (CO₂) ice as it sublimates in the summer and condenses at the poles, causing tiny changes in the rotation rate of Mars, translating into a variation in the length of its days.

Objectives

The goals of the RISE experiment are to deduce the size and density of the Martian core through estimation of the

precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In o ...

and

nutation Nutation () is a rocking, swaying, or nodding motion in the axis of rotation of a largely axially symmetric object, such as a gyroscope, planet, or bullet in flight, or as an intended behaviour of a mechanism. In an appropriate reference fra ...

of the spin axis. The precession and nutation estimates will be based on measurements of the relative velocity of the ''InSight'' lander and tracking stations on Earth known as the

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

. The perturbations resemble the wobble of a spinning top and occur on two time scales. The longer wobble, called

, takes about 165,000 years and it is directly related to the mass and diameter of the iron-rich core. The shorter-period wobbles, called

s, occur on time scales of less than a year and are extremely small. Since they are determined by the density of the core, they will help determine if the core is mostly liquid or solid. This study will also help scientists understand why Mars's magnetic field is so weak, as compared to Earth's. PIA22232insightlandingonmars

References

External links

*Home site o
RISE
at NASA {{Portal bar, Astronomy, Chemistry, Geology, Solar System, Science InSight Geology of Mars Spacecraft instruments

Overview

Objectives

See also

References

External links