 | Parts of this article (those related to Kazachok is cancelled, what about LaRa?) need to beupdated. Please help update this article to reflect recent events or newly available information.(October 2025) |
| Operator | ESA &Roscosmos |
|---|---|
| Manufacturer | Antwerp Space N.V.[1] |
| Instrument type | Radio science/Transponder |
| Function | Monitor the rotation and orientation of Mars |
| Mission duration | Planned: ≥ 1 Earth year[2] |
| Website | lara |
| Properties | |
| Mass | less than 2.2 kg[3] |
| Dimensions | Length: 23 cm for the transponder (7-9 cm for the antennas)[3] |
| Power consumption | ≈ 40W[3] |
| Spectral band | X band (uplink: 7.174 GHz, downlink: 8.428 GHz) |
| Host spacecraft | |
| Spacecraft | Kazachok |
| Operator | ESA &Roscosmos |
| Launch date | August–October 2022[4] |
| Rocket | Proton-M/Briz-M |
| Launch site | Baikonur |
LaRa (Lander Radioscience) was a Belgian radio science experiment that will be placed onboardKazachok, planned to be launched in 2022.[2][4] LaRa will monitor theDoppler frequency shift of a radio signal traveling between the Martian lander and theEarth. These Doppler measurements will be used to precisely observe the orientation and rotation ofMars, leading to a better knowledge of the internal structure of the planet.[5][6]
Kazachok was cancelled, and the ExoMars mission was moved to 2028.
LaRa will obtain coherent two-way Doppler measurements from theX band radio link betweenKazachok and large antennas on Earth, like those of theDeep space network. The relative radial velocity between the Earth and the Martian lander is inferred from Doppler shifts measured at the Earth ground stations.Masers at the Earth's ground stations ensure the frequency stability.[6]Véronique Dehant, scientist at theRoyal Observatory of Belgium, is thePrincipal Investigator of the experiment.[2][7]
Antwerp Space N.V.,[1] a subsidiary ofOHB SE, is the manufacturer of the LaRa instrument.[2] The main parts of the transponder are the coherent detector, the transmitter with the solid-state power amplifier, themicro controller unit, the receiver and thepower supply unit. TheAllan deviation (quantifying the frequency stability of the signal) of the measurements is expected to be lower thanat 60 second integration time.
The LaRa high-performance antennas were designed at theUniversité catholique de Louvain inBelgium to obtain an optimalantenna gain centered on an elevation (angle of the line-of-sight from the lander to Earth) of about 30° to 55°.[8] There will be three antennas: two for the transmission (for redundancy purposes) and one for reception.[9] Cables connect the transponder to the three antennas.
Belgium and theBelgian Federal Science Policy Office (BELSPO) fund the development and the manufacturing of LaRa throughESA's PRODEX program.[10]
LaRa will study the rotation of Mars as well as its internal structure, with particular focus on itscore. It will observe the Martianprecession rate, thenutations, and thelength-of-day variations, as well as thepolar motion. The precession and the nutations are variations in the orientation of Mars's rotation axis in space, the precession being the very long term motion (about 170 000 years for Mars) while the nutations are the variations with a shorter period (annual, semi-annual, ter-annual, periods). A precise measurement of the Martian nutations enables an independent determination of the size and density of the liquid core because of aresonance in the nutation amplitudes.[11] The resonant amplification of the low-frequency forced nutations depends sensibly on the size,moment of inertia, and flattening of thecore. This amplification is expected to correspond to a displacement of between a few to forty centimeters on Mars surface.[12] Observing the amplification allows to confirm the liquid state of the core and to determine some core properties.
LaRa will also measure variations in the rotationangular momentum due to the redistribution of masses, such as the migration of ice from thepolar caps to the atmosphere and the sublimation/condensation cycle of atmospheric CO2.[13]
ExoMars programme | ||||||
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| ExoMars 2016 |
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| 2028 launch |
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| Related | ||||||
