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Detection of Calcium on the Moon

Detection of Calcium on the Moon

8 June 2005

During the Lunar commissioning phase, SMART-1's payload already produced interesting science results. Taking advantage of a solar flare, the D-CIXS instrument detected the calcium element on the lunar surface from its X-ray fluoresence.

SMART-1 payload commissioning sequences were run in April. As expected the instruments performances are very sensitive to the thermal conditions in Lunar orbit. Therefore specific operating conditions have been arranged to limit the exposure of the panel supporting the SIR and D-CIXS instruments.

These conditions also constrain the downlink pointing to Earth, especially around new moon, as the remote sensing payload are mounted on the opposite side of the spacecraft from the communication medium gain antennas.

Science Results from Lunar commissioning

Data obtained by D-CIXS during a solar flare allowed for the first time the detection from orbit of the calcium element on the Moon. The operating parameters had to be fine-tuned to adapt to the thermal conditions of the spacecraft and instrument.

Top Left: GOES X-ray spectrum showing the Solar input. Note the flares around 06:00 UT on 15 January 2005 (GOES Data Courtesy NOAA).
Lower Left: D-CIXS spectrograms showing fluorescence emission from the Moon as a response. The three panels show the summed outputs of the three separate D-CIXS facets.
Top Right: Area of the Moon overflown during this observation, running from 15° to 45° North, at 60° East longitude, including Mare Crisium in the southern part of the overflown region.
Bottom Right: The derived X-ray spectrum, indicating lunar elemental composition. Note the prominent calcium feature, as well as visible aluminium, silicon and iron.  Credit: ESA/D-CIXS

D-CIXS X-ray spectrum of the Moon.  Credit: ESA/D-CIXS


Observations of the Moon by SIR made during the commissioning period show differences of infrared reflectance between the highlands and maria.

Flux variations recorded by the SIR infrared spectrometer over one orbit at 30 degrees longitude East, showing differences of infrared reflectance between highlands and maria. In particular note the large drop corresponding to Mare Tranquillitatis from 0 to 20 degrees North.  Credit: ESA/SMART-1/Max Planck Society.

In addition, the SIR experiment has conducted a pointing of Jupiter to refine the wavelength calibration.


The first results obtained at the Moon have been presented at several international conferences, including:

  • Lunar Planetary Science Conference in Houston (14-18 March)
  • Lunar session at European Geoscience in Vienna (on 28 April and at a press briefing on 25 April), including a SMART-1 science and technology working team meeting
  • Lunar Science Conference: "the Next Decade" in Bad Honnef, Germany (6-10 June 2005)

The following specific instrument science team meetings took place over the last seven weeks:

  • SMART-1 plasma working group at ESTEC (22 April)
  • D-CIXS at Rutherford Appleton Lab (16-17 May)
  • AMIE science team at Toulouse Observatory Midi-Pyrenees (24-25 May)


Prof. Manuel Grande, SMART-1 D-CIXS Principal Investigator
CCLRC, Rutherford Appleton Laboratory
Tel: 01235 446501

Bernard H. Foing, ESA - SMART-1 Project scientist
Tel: + 31 71 565 5647


Last Update: 1 September 2019
23-Jul-2024 14:33 UT

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