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TO 19C



The Xelene lander mission (TO 19C, or Masten Mission 1) was designed to bring eight payloads to the lunar surface near the south pole and operate them for 14 days. Science objectives included studying plume-surface interactions, regolith geophysical properties, the surface radiation environment, polar regolith thermal properties, mineralogy, and hydrogen content, and composition of the lunar exosphere, possibly including volatiles from ices. The lander mission was selected through NASA's Commercial Lunar Payload Services (CLPS) initiative, in which NASA contracts with a commercial partner, in this case Masten Space Systems, that provides the launch and lander.

The Xelene lunar lander, in the XL-1 configuration, has a dry mass of 675 kg and carries about 2000 kg of propellant. It has 6 main engines and 12 auxiliary thrusters. The has eight payloads, comprising nine science and technology instruments. The payloads are the Lunar Compact Infrared imaging System (L-CIRiS), the Linear Energy Transfer Spectrometer (LETS), the Heimdall Camera, the Mass Spectrometer observing Lunar operations (MSoLo), the Near-Infrared Volatile Spectrometer System (NIRVSS), the Laser Retroreflector Array (LRA), the Sample Acquisition, Morphology Filtering, and Probing of Lunar Regolith (SAMPLR) robotic arm. It also carries the MoonRanger micro rover, with a neutron spectrometer to measure hydrogen content of the local surface regolith. Commercial payloads may also be added.

The mission plan calls for the lander to launch from Cape Canaveral on a SpaceX booster and go into lunar orbit. It will then descend to land near the rim of Haworth crater near the south pole, operating for about 12 days before lunar nightfall. Objectives of the mission include assessing the composition of the lunar surface, evaluating the radiation environment, and testing precision landing technologies.

For more on NASA's CLPS initiative and missions, see:

Image credit: Masten

Alternate Names

  • XL1Lander

Facts in Brief

Launch Date: 
Launch Vehicle: 
Launch Site: Cape Canaveral, United States
Mass: 675 kg


  • Planetary Science

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. John GruenerProject ScientistNASA Johnson Space
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