Astronomy from the Moon: Planned Observations for ILO-X Lunar Astronomy Imagers in 2024

30 January 2024

International Lunar Observatory Association, 65-1230 Mamalahoa Hwy D20, Kamuela HI 96743 USA, info@iloa.org

Contributing Authors: ILOA Hawai’i Executive Committee: Director Steve Durst, Elisa Perednia, Keenan Thompson; ILOA Lunar Astronomer Consultant Ana Mosquera; ILOA Astronomers / Board Members: Yuki Takahashi, David Schrunk, Bill Carswell, Margarita Safonova, Chatief Kunjaya; Canadensys Aerospace Corporation.

BACKGROUND:

The International Lunar Observatory Association (ILOA Hawai’i) is an interglobal enterprise incorporated in Hawaii as a 501(c)(3) non-profit since 2007 to help realize a multifunctional lunar observatory for long-term astronomy, science and exploration at the Moon South Pole, and to participate in human lunar base build-out - with Aloha.  The flagship ILO-1 observatory is being planned for long-term astrophysics and communications from the Moon south pole region, specifically from Malapert Massif Point E.

Astronomy from the Moon has been imagined since at least the 1600s. J. Kepler describes how Earth may look when viewed from the Moon in Somnium which is considered the first serious scientific work on lunar astronomy [1].  Beyond the advantages for far side radio observations avoiding terrestrial interference, the lunar environment offers a thin exosphere, no atmospheric-related problems (such as wind), permanent darkness in polar craters / cold traps (for cooling infrared instruments), a large and stable platform to perform interferometry with long baseline arrays, slow sky rotation allowing long exposure times, and access from future lunar bases for observatories’ service and upgrades.

The pioneering astronomical lunar telescope was on Apollo 16 in 1972, a 76.2 mm Schmidt telescope with far-ultraviolet camera/spectroscope operated by Astronaut John Young [2]. In 1990, The American Institute of Physics held a conference on “Astrophysics from the Moon”. In 1997, ESA conducted an in-depth study on “Very Low Frequency Array on the Lunar Far Side” [3]. China revitalized astronomy from the Moon in the 21st century with the 2013 Lunar-based Ultraviolet Telescope (LUT), a 150 mm Ritchey–Chrétien NUV telescope operated on the Chang’E-3 lander at Mare Imbrium. ILO-X instruments, developed by Canadensys Aerospace Corp. for International Lunar Observatory Association (ILOA Hawai’i), are set to launch to the Moon aboard Intuitive Machines’ IM-1 mission Nova-C lander during a multi-day launch window that opens 14 February 2024. The ILO-X mission is a precursor to test technologies for the future ILO-1 and ILO-2 observatories. 

ILO-X INSTRUMENT SUITE:
Miniaturized optics are designed to withstand extreme lunar temperature swings (-180°C to +70°C) and large onboard memory storage (32 GB per instrument), allowing uplink/downlink to be timed according to operational logistics of the mission. 

  • Wide FOV Imager:
      • Circular FOV with full angle of 186°
      • Pixel resolution of ~0.06° per pixel
      • Bayer colour detector, circular image diameter 3000 pixels
  • Narrow FOV Imager:
    • Rectangular FOV, 39° x 51°
    • Pixel resolution of 0.013° per pixel
    • Bayer colour detector, 3000 pixels x 4000 pixels
    • Baffle for straylight mitigation – both from Sun and lunar surface.
    • The magnitude limit for the currently planned exposure-times ranges from about 7.5 to 9 on Earth, and will improve significantly on the Moon. 
      • Note that within 90 seconds the astronomical object will move 1 pixel due to lunar rotation.

ILO-X MOUNTING ON INTUITIVE MACHINES’ IM-1 MISSION NOVA-C LUNAR LANDER:
The Nova-C Lander is a hexagonal cylinder, 4.3 meters tall and 1.57 meters wide, on 6 landing legs with a launch mass of 1,908 kg. It is capable of carrying approximately 130 kg of payload to the surface. It uses solar panels to generate 200 W of power on the surface, using a 25 amp-hr battery and a 28 VDC system. Propulsion and landing use liquid methane as fuel and liquid oxygen as an oxidizer powering a 3100 N main engine mounted on the bottom of the lander. Communications are via S-band.

ILO-X instruments mounted on the lander will be about 4.5 meters above the surface.

  • Wide FOV Imager:
      • Fixed mounting, no moving parts
      • Near-horizontal orientation   
  • Narrow FOV Imager:
    • Fixed mounting, no moving parts
    • Assuming the lander lands in its nominal orientation, the NFoV bracket directs the boresight towards 0 degrees azimuth (local north) and 40.5 degrees elevation above the horizon.
      • Note: Pointing above 30° removes the problem of the lunar `horizon glow' - a reported scattering of sunlight by lunar dust 'atmosphere' [4].
Img 2

ILO-X PRIMARY OBSERVATIONAL GOALS:

  • Milky Way Galaxy / Center
  • Proposed objects (or proposed target- areas) from 10 international Invited Observations 
  • Other celestial sky observations
  • Earth / other planets
  • Lunar surface near the lander and out to the local lunar horizon 

Based on the instrument design, configuration, and mission duration, the focus of the observations is highly recommended to be on very extended objects and time-domain-astronomy. Target-of-opportunities observations may occur (for example, unforeseen astronomical events such as supernovae).

ILO-X ENGINEERING UNITS’ TEST IMAGES FROM EARTH:

PLANNED ILO-X IMAGING:

INTENDED IN-TRANSIT CHECKOUT OBSERVATIONS:
On the way to the Moon (15-21 February 2024).

  • Narrow FOV Imager:
    • 3 long exposures intended for dark sky (15 seconds, 20 seconds and 30 seconds at 6 dB Analog Gain).
  • Wide FOV Imager:
    • 1 long and 2 short exposures with uncertain target (0.25 millisecond, 0.50 millisecond and 20 seconds).

LUNAR ORBIT OBSERVATIONS:
Prior to lunar landing (15-21 February 2024).

  • Narrow FOV Imager:
    • 3 exposures intended for the lunar surface (0.4 millisecond, 1 millisecond and 2.5 milliseconds).
      • Note: if opportunity presents
    • Wide FOV Imager:
      • 3 exposures intended for the lunar surface (0.4 millisecond, 1 millisecond and 2.5 milliseconds).
        • Note: if opportunity presents

DE-ORBIT, DESCENT AND LANDING OBSERVATIONS:
Comprehensive recording of de-orbit through to post-landing (22 February 2024).

  • Wide FOV Imager:
    • 480 raw images: 80 brackets of 6 exposures each.

LUNAR SURFACE LANDING:
Landing occured 22 February 2024. Original landing site is designated to be near Malapert A crater (80.3°S, 1.2°E); landing accuracy was within 200 meters of its intended landing site.

ILO-X EXPECTED OBSERVATIONS FROM LUNAR SURFACE IN FEBRUARY 2024:
ILO-X instruments should operate on the surface for nearly two weeks.

  • Narrow FOV Imager:
    • For the Milky Way Galaxy / Center: 3 long exposures (3 x 30 seconds, 3 x 20 seconds and 3 x 15 seconds) in 3 brackets of 3 images each, 1 bracket of the same 3 exposures of optically black region.
    • Known targets of interest within FOV: Eta Carinae Nebula (Carina Nebula), Alpha Crucis (Acrux), Hadar (Beta Centauri), Large Magellanic Cloud, Mimosa (Beta Crucis)
      • Note: there is a transient artifact filter function that can remove unwanted streaks from energetic particles prior to downloading.
    • Wide FOV Imager:
      • For Lunar Sky: selectable long exposure bracket of 3 repeats.
      • For Lunar Landscape: selectable wide exposure range brackets of 8 exposure time values.
        • Known targets of interest within FOV: Milky Way Galaxy rising from lunar horizon.

ILO-X INVITED OBSERVATIONS:

1. Her Royal Highness Princess Maha Chakri Sirindhorn / Thailand 6. Christian Veillet / Large Binocular Telescope Observatory, Arizona, USA
2. Gilles Leclerc / Canadensys Aerospace Corp., Canada 7. R. Pierre Martin / University of Hawai’i at Hilo, USA
3. Suijian Xue / NAOC-CAS, China 8. Leinani Lozi / ILOA Cultural Astronomer, Hawai’i, USA
4. Dante Minniti / Universidad Andrés Bello, Chile 9. Bernard Foing / Leiden University, Netherlands
5. Bodo Ziegler / University of Wien, Austria 10. Margarita Safonova / Indian Institute of Astrophysics, India

Suggestions from Invited Observations:

  • Close binary systems, and variable stars.
  • Images of the MWG and Solar System planets.
  • Nearby clusters of galaxies (such as Virgo or Coma).
  • Magellanic Clouds (Note: may not visible with current ILO-X pointing angle).
  • The most distant object we can see with the naked eye (i.e. Andromeda Galaxy / M31); (Note: may not be visible above lunar horizon during current landing window).
  • Comet 12P/Pons-Brooks.
  • Image lunar landscape and compare it to Mauna Kea as analog with emphasis on H2O effects on regolith / lava.
  • Comparison of astronomical seeing/ light-gathering which ILO-X is able to achieve on Moon to its performance on Earth, and to other telescopes including Lana'i 1-m telescope used by Ohana Kilo Hoku group.

OTHER EXPECTED ACHIEVEMENTS FROM ILO-X MISSION:

  • Technology validation for astronomy from the Moon.
  • Add to global data sets of lunar astrophysics; for example, experience with lunar data from Chang’E-3 Lunar Ultraviolet Telescope (LUT) may provide salient insight.
  • Interactions between ILOA lunar astronomy and other Hawai’i-based astronomy organizations, particularly Mauna Kea Observatories.
  • Characterize the performance of the ILO-X cameras on the lunar surface, as their temperatures vary due to synodic rotation period.
  • Characterize the effects of any lunar dust contamination on the ILO-X camera lenses.
  • Compare lunar surface images for potential micrometeoroid impacts or changes.

REFERENCES:

[1] Kepler, J., (1634), Somnium, seu opus posthumum astronomia lunari. [2] Carruthers, G. R. and Page, T. (1972) Science, 177, 788-791. [3] ESA (1997) Technical Report ESA SCI(97)2. [4] Murthy, D. L. and Vondrak, R. R. (1993) Lunar and Planetary Institute Science Conference Abstracts, 24, 1033.

ACKNOWLEDGEMENTS:
Thanks to Intuitive Machines, ILOA Lunar Astronomer Consultant Chien-Hsiu Lee, Canadensys Aerospace Corporation: Christian Sallaberger, Frank Teti, John Hackett, Janine Newhook, Josh Newman, Don McTavish, Kieran Carroll, et al