View source for Rotation and Interior Structure Experiment

{{Infobox spacecraft instrument
| Name = RISE (Rotation and Interior Structure Experiment)
| Image =
| Caption =

| Operator = [[NASA]] / [[JPL]]
| Manufacturer = JPL
| Type = [[Outline of radio science|Radio science]]
| Function = Constrain the core of Mars
| Mission_Duration = 2 years
| Began = Landing: 26 November 2018
| Ceased = <!--date operations ceased (single instruments only)-->
| Webpage = {{url|https://mars.nasa.gov/insight/spacecraft/instruments/rise/}}

| Mass = {{cvt|7.3|kg|abbr=on}}
| Dimensions = 19.8 L<sup>3</sup><ref name="Home RISE"/> 
| Power_consumption = 78 [[Watt|W]]<ref name="Home RISE"/>
| Resolution = 
| Spectral_Band = [[X band]]<ref name="Home RISE"/>
| Data_Rate =

| Spacecraft = ''[[InSight]]'' Mars lander
| SC_Operator = NASA
| Launch = 5 May 2018 
| Rocket = [[Atlas V]] 401
| Launch_Site = [[Vandenberg Air Force Base|Vandenberg]] [[Vandenberg AFB Space Launch Complex 3|SLC-3E]]
| COSPAR = 2018-042A
}}
'''Rotation and Interior Structure Experiment''' ('''RISE''') is a radio science experiment onboard ''[[InSight]]'' Mars lander that will use the spacecraft communication system to provide precise measurements of [[Mars]]' 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 [[Planetary core|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 ==

[[File:PIA19664-MarsInSightLander-Assembly-20150430.jpg|thumb|The ''Insight'' lander with its solar panels deployed in a cleanroom]]
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]]. RISE uses the spacecraft's radio connection with Earth to assess perturbations of Mars's rotation axis to within 10 centimeters.<ref name="2018 Press Kit">[https://www.jpl.nasa.gov/news/press_kits/insight/landing/download/mars_insight_landing_presskit.pdf Mars InSight Landing Press Kit]. (PDF) NASA. Published: November 2018.</ref><ref name="Agle 2018">[https://www.jpl.nasa.gov/news/news.php?feature=7216 NASA's InSight Passes Halfway to Mars, Instruments Check In.] D. C. Agle, ''NASA News''. 20 August 2018.</ref> These measurements can provide information about the size and composition of Mars's [[Planetary core|core]].<ref name="Agle 2018"/><ref name="Folkner 2018">[https://link.springer.com/article/10.1007/s11214-018-0530-5 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. {{doi|10.1007/s11214-018-0530-5}} Online {{ISSN|1572-9672}}</ref>

The radio science equipment is largely the same as used for the [[Mars Exploration Rover]] mission,<ref name="Folkner 2012"/> and it includes two medium-[[Gain (electronics)|gain]] [[horn antenna]]s (MGAs) on the lander deck, and an [[X band]] radio [[transponder]] (8&nbsp;GHz) and transmitter inside the lander, where electronics can be shielded from the harsh conditions of space.<ref name="Agle 2018"/><ref name="Folkner 2012">[https://www.lpi.usra.edu/meetings/lpsc2012/pdf/1721.pdf 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.</ref> Although the lander will communicate all other science data in [[UHF]] to relay orbiters, the X band can be used directly with Earth in case of some problems with relay through an orbiter.<ref name="Folkner 2012"/>

In principle, after ''[[InSight]]'' lands on Mars, the lander reflects a signal sent from Earth, revealing its exact location and velocity in space.<ref name="Home RISE">[https://mars.nasa.gov/insight/spacecraft/instruments/rise/ Mars InSight Mission - RISE]. NASA/JPL. Accessed: 12 November 2018.</ref> In doing so, the experiment measures changes in the signal, known as the [[Doppler effect]] 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.<ref name="Agle 2018"/> A planet with a liquid core will wobble more as it spins, compared to one that is solid at its core.<ref name="2018 Press Kit"/><ref name="Home RISE"/>

The sensitivity is such that RISE can also detect the rotation changes caused by the seasonal redistribution of carbon dioxide (CO<sub>2</sub>) 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.<ref name="Agle 2018"/><ref name="Folkner 2012"/>

== Objectives==

[[File:Terrestrial Planet Interiors (Earth, Mars and Moon) - Artist's Concept.jpg|thumb|right|250px|Interiors of Earth, Mars and the Moon (artist concept)]]
The goals of the RISE experiment are to deduce the size and density of the Martian [[Planetary core|core]] through estimation of the [[Axial precession|precession]] and [[nutation]] 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]].<ref name="Folkner 2012"/>

The perturbations resemble the wobble of a spinning top and occur on two time scales. The longer wobble, called [[Axial precession|precession]], takes about 165,000 years and it is directly related to the mass and diameter of the iron-rich core.<ref name="2018 Press Kit"/> The shorter-period wobbles, called [[nutation]]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.<ref name="2018 Press Kit"/><ref name="Folkner 2018"/> This study will also help scientists understand why Mars's magnetic field is so weak, as compared to Earth's.

[[File:PIA22232insightlandingonmars.jpg|thumb|center|700px|''InSight'' landing zone target with other NASA landing zones]]

==See also==
*[[LaRa]], a similar radio science experiment on the ExoMars lander

==References==
{{reflist}}

==External links==
*Home site of [https://mars.nasa.gov/insight/spacecraft/instruments/rise/ RISE] at NASA

{{Insight}}
{{Mars}}
{{Geography of Mars}}
{{Satellite and spacecraft instruments}}
{{Portal bar|Astronomy|Chemistry|Geology|Solar System|Science}}

[[Category:InSight]]
[[Category:Geology of Mars]]
[[Category:Spacecraft instruments]]