Prospect – searching for water at the lunar poles

Near the Moon’s South Pole, Prospect will:

• Drill into the lunar surface in search of very cold samples of regolith, the upper layer of loose dust and fragmented rock on the Moon's surface.
• Analyse the samples using an instrument suite, searching for volatiles such as water ice.
• Study the overall composition of the Moon to understand the environment at the lunar poles.
• Demonstrate the potential of in-situ resource utilisation (ISRU) for future exploration by extracting oxygen from lunar regolith.

ESA’s Prospect payload package is a comprehensive suite of hardware designed to access samples at the Moon’s poles, seeking out locations cold enough to harbour icy volatiles such as water ice.

Investigation of samples from the poles, including any volatiles they may contain, can teach us about how water and other important elements arrive on the Moon, where they come from, and how they behave on the surface.

As well as helping us understand the history of water in the Earth-Moon system, such materials could represent possible sources of water, oxygen and fuel for future explorers.

Prospect will reach the lunar surface with the Intuitive Machines’ Nova-C lunar lander, as part of NASA’s Commercial Lunar Payload Services (CLPS) programme.

Mission overview

Prospect operations will take place over the course of one lunar day, or about 10 Earth days. The landing platform Nova-C will provide both power and communications, as well as hosting the drilling system within reach of the lunar surface.

• Prospect will land near the Moon’s South Pole onboard the Intuitive Machines’ Nova-C lunar lander.
• Prospect will release its hold down mechanisms to free the drilling system for surface operations. 
• Prospect will image the surface in different colours using its camera and lighting system, which can reveal details about the regolith composition and highlight any obstacles to drilling.

• With a GO from ground control on Earth, Prospect will start drilling into the lunar surface with enough mechanical power to cut through even icy regolith and using a dedicated electrical sensor to scan the subsurface for signs of water ice.
• Once at the target sampling depth, Prospect will use a sampling tool to acquire the regolith sample, return it to the surface and transfer it to the instrumentation package
• Working quickly to avoid the loss of any icy material to the vacuum of space, the instrument package takes a picture of the sample before sealing it into a sample oven, where it is gradually heated to release sample gas.
• Prospect’s instrumentation then analyses the sample gas to understand its composition and volatile content, as well as the results of experiments to demonstrate in-situ resource extraction processes.
• After transmitting all the acquired data via the lander to ground, Prospect is ready to drill deeper into the surface looking for even colder samples.

5 things to know

• Why does Prospect need to drill? Icy volatiles are expected to be found at the coldest places on the Moon. While the floors of permanently shadowed craters may offer the best chance of finding ice, the extreme cold and lack of solar power makes surface operations extremely challenging. Prospect seeks to land nearby such craters, where sunlight can still provide solar power but only grazes the surface. At such locations, temperatures are predicted to fall rapidly even a few 10s of centimetres into the surface, and the Prospect drill will search for ice deposits within this frozen subsurface.

• How does Prospect extract volatiles? By controlling the heating of the lunar samples in its ovens, Prospect can gradually release volatiles from the regolith, heating the material up to temperatures of nearly 1000°C. However, the drilling and sample handling must also take care to prevent premature heating of the regolith, and risk losing cold trapped icy material, before it is sealed within the oven. In addition to extracting volatiles by heating, Prospect plans to introduce hydrogen to the ovens to demonstrate one potential chemical process for in-situ resource extraction from minerals.
• How does Prospect detect volatiles? Before even analysing the lunar samples, Prospect will use its multi-spectral imaging system plus its permittivity sensor to scan the lunar material for signs of volatiles, including water ice. Once the sample gas has been released by heating a drilled sample, Prospect can use either its ion-trap mass spectrometer or its magnetic sector mass spectrometer. These instruments will scan the sample for different volatile species, assess the relative quantities, and analyse the ratios of specific isotope to help understand their origin.
• How long will Prospect operate? Surviving the extreme cold of lunar night is a major challenge for landers and their payloads. Since the mission is not planned to survive through the night, Prospect must maximise its use of the lunar daytime available and share resources with the other payloads on the platform. Prospect is expected to operate for between 5 and 10 Earth days, depending on final mission profile.
• Where will Prospect land? Deciding on the best landing site for Prospect involves balancing several different factors. These include having enough sunlight available to provide solar power, but not so much as to heat the regolith above the cold temperatures associated with icy volatiles. The site must also have sufficient communications access, either via direct line-of-sight to Earth, or use of orbital telecommunications relays. Lastly, the landing area must be relatively clear of hazards including boulders and high slopes for a safe landing. The current landing site, balancing these conditions, is ~84.5 degrees South and ~31.5 degrees East near the lunar South Pole. The final landing site will be confirmed by NASA and the company responsible for landing.

Quick facts

• Launch date: 2027
• Lunar lander: Nova-C
• Components: ProSEED drilling system + ProSPA instrumentation suite + Prospect control electronics
• Mass: ~45kg
• Drilling depth: up to 1m beneath the surface
• Number of samples: ~15 samples depending on time to acquire and analyse each one
• Scientific instrumentation: Ion-trap mass spectrometer, magnetic sector mass spectrometer, permittivity sensor, multispectral imaging system

Who is involved

Prospect is supported by a team of scientists from across Europe and beyond, who assist in planning the operations and who will help analyse the data delivered by the package. Prospect is part of ESA’s Exploration Envelope Programme (E3P) and is managed by the Directorate of Human and Robotic Exploration.

Leonardo in Italy are the Prime Contractor developing Prospect and are also the technical lead of the drilling and sampling system (ProSEED).

The Open University in the UK lead the development of the ProSPA instrumentation suite, which will analyse the samples acquired by the drill.

Prospect involves a broad team of subcontractors and suppliers from across Europe, including Italy, the United Kingdom, Germany, Spain, Poland, Switzerland, France, and Belgium.

NASA support Prospect via the Commercial Lunar Payload Services programme, which realises delivery and operations of payloads to the lunar surface.

Story so far

From the time of the Apollo missions, the Moon was considered to be a dry body without the conditions for stable water.

More recent observations from orbit and using ground-based radio telescopes suggest the presence of water ice.

During the NASA LCROSS mission, observation of the impact of a rocket upper stage into the Moon’s south polar region and the resulting plume provided the most direct measurements of potential water ice.

Prospect is being developed using the experience gained through the Rosetta mission including both the SD2 drill and Ptolemy instrument suite, the ExoMars drill and Beagle-2 instrumentation.

Development of Prospect has been under way for several years already, including the production and testing of prototype hardware both drilling into icy lunar regolith simulant as well as running test analyses of sample analogue material.

A version of Prospect’s ion-trap mass spectrometer (PITMS) already flew onboard the first CLPS mission Peregrine 1, which while unsuccessful in reaching the lunar surface, demonstrated that the instrument could survive and operate in the harsh environment of space.

ESA is developing Prospect as part of its overall contribution to international lunar exploration efforts, including preparation for its involvement with the NASA Artemis programme and the return of humans to the Moon.