The L-Cam Project

A lunar-based telescope for astronomical observations

The Team

Jessie Christiansen, Caltech/IPAC

Tabetha Boyajian, LSU

Carol Miu, LSU, UW Bothell, Collin College

Franck Marchis, SETI Institute & Unistellar

Angelle Tanner, MSU

Farzaneh Zohrabi, LSU

Matthew Penny, LSU

Connor Langevin, LSU

Jonas Klüter, LSU

Peter Santana, UPRM, SETI Institute & Unistellar

Acknowledgement: This project is funded in part by the Gordon and Betty Moore Foundation through Grant GBMF10467 to AstronetX PBC. Participation of CM made possible by the LSU REU program (NSF award PHY-1852356). Participation of PS-R made possible by the SETI

Institute REU program (NSF award 2051007).

The Moon

● Only one side of the Moon is visible from Earth

● Schrodinger Basin: 75°S, 135°E

Why put a telescope on the Moon?

● Stable environment/no atmosphere ● Continuous monitoring of the sky for

two weeks at a time ● Can observe objects in Earth’s

daytime sky Schrodinger Basin

What does the sky look like from the Moon?

L-Cam full-field image (from Earth) with the Moon

Science Motivation: Exoplanet transits

Anticipated results:

● Detecting new transiting exoplanets

● Refine orbits● Characterize

properties

Video credit: NASA

Science Motivation: Asteroids

Anticipated results:

● Rotation, Shape and multiplicity of 100s asteroids, mostly in the main-belt

● Mutual events in multiple asteroid systems

Video credit: Descamps et al. 2008

First Planetary Defense Facility on the Moon

- A Planetary Defense telescope on the moon to complement Earth-based ones

- At least one Near-Earth Asteroid observable with L-CAM every month

- Science goals: orbit, shape, moon around known potentially hazardous asteroids

Potentially Hazardous Asteroid 1km 1994PC1 observed on January 7 2022 from NZ (individual 4-s frames combined together). Credit: Unistellar/SETI Institute

Scope of work I

● Characterize the instrument○ Configure instrument for optimal data

quality and science productivity

L-Cam design

Models of the first two NASA commercial landers L-Cam example reference image

Scope of work II

● Science program○ Create lists of science

targets to observe for a 12 month period.

○ Establish observing plan○ Develop data calibration

and analysis plans ○ Evaluate different

strategies to accommodate daily download rates/limits

All sky map showing L-Cam footprint at the first of each month in 2024. Constellations are traced and labeled in orange. Naked-eye exoplanet host stars are marked in blue.

Summary: The Dawn of Astronomy on the Moon?

● Targeted launch in 2024, operating for 1 year

● Light curves of ~4 dozen planet hosting bright stars and 100s of main-belt asteroids

● Detection and characterisation of dozen near-Earth asteroids

Potential Targets for Investigation: Known Exoplanet Hosts

All sky map showing LCAM footprint (red) at the first of each month in 2024. Constellations are traced and labeled in orange. Exoplanet host stars with Vmag < 6.5 marked in blue.

L-Cam Field of View

● From Schrodinger Basin, elevation ~25° ● Nominal pointing direction: L2 (ecliptic)● 20x25°FOV

Above: All sky map in celestial coordinates showing characteristic LCAM footprint (red) at the first of each month in 2024. Constellations are

traced and labeled in orange.

Science Motivations

1) Transiting Exoplanetsa) Improve ephemerides of known transiting planets b) Estimates of Transit Timing events (TTVs) c) Complement K2 and TESS surveys of the eclipticd) Discover additional planets in known systems with an extended photometric baseline

2) Asteroids a) Spin period & Shape modeling (231 new measurements in stationary mode)b) Long period asteroids (10 of them in stationary mode)c) Multiple Asteroids by mutual events or multi-period lightcurves d) Follow-up on recently discovered NEAs - looking nearby the sun (1 target per month)

● Can observe objects in daytime sky from Earth ● Citizen science

Transiting Exoplanets

● Transit frequency gives us the orbit radius

● Transit duration & depth provides the planet radius

● Size and mass (with RV) provides planet density which hints at composition

● Orbit radius and stellar effective temperature tells us if the planet is in the habitable zone

Chen & Kipping 2017

Cameras in space

Aperture Waveband Pixel scale FOV Camera type Target observing timeMagnitude

range

Kepler/K2 1-m 400-900 nm 3.98"/pixel 10 x 10 ° CCD 4 years 8-16

TESS 10-cm 575-1100 nm 21"/pixel 24 x 96 ° CCD 27-351 days8-13 (I band)

LCAM - 8" pix 5-cm 500-800 nm* 8" / pixel 20 X 25 ° CMOS several days 4.5 - 16

LCAM - 12" pix 5-cm 500-800 nm* 12" / pixel 20 X 25 ° CMOS several days 4.5 - 16*

ASTERIA 6-cm 500-900nm 15.8 "/pixel 11.2 x 9.6 ° CMOS 3 months prime <6

MOST 15-cm 350-750nm 3" /pixel 1 x 1 ° CCD 0.4-6.0

CoRoT 27-cm 400-1000nm 2.32 "/pixel 6 x 6 ° CCD 7 yr, 5 mo, 20d 5.4-16

EPOXI 30-cm 350-1000nm 0.41"/pixel 0.12 ° CCD 1-3 weeks 10-12

NEO Surveyor

*depending on readout mode, desired SNR and total exposure time.

Survey: Known Exoplanet Host Stars

Observation durations:

● Stationary: targets spend ~52h in FOV● Side nodding enabled: allows for 2-3x stationary duration● Vertical nodding enabled: expands the FOV to more negative

declinations

Target availability:● Must be daylight & Sun must be > 10° from FOV● For one year:

○ ~44 total light curves■ Nominal field has ~22 eligible targets over 1y■ At a given time, ~2 targets in FOV ■ Nod to avoid Sun 1x/month for ~90h(3.5d),

adds ~22 new targets ○ ~12d (cumulative) time on each nominal field target

assuming no FOV movements○ ~30d (cumulative) time on each nominal field target

assuming azimuthal FOV movements ○ ~3.5d each lunar day lost to Sun avoidance → slew

to observe new field during this time

Aitoff projection showing LCAM FOV for December 1, 2024. Blue points mark known exoplanet host stars with 4<Vmag<6.5, and red boxes mark potential comparison stars with 4<Vmag<6.5.

Observation durations:

● Stationary: targets spend ~52h in FOV

● Side nodding enabled: allows for 2-3x stationary duration

● Vertical nodding enabled: expands the FOV to more negative declinations

Target availability:Assume: Must be daylight & Sun must be > 10° from FOVAnswer: For one year: ~12d cumulative (~4d lost due to Sun avoidance → slew to observe new field during this time)

Survey: Known Exoplanet Host Stars

● Comparison stars○ selected to be bright (V<6.5), solar type

(FGK), and nearby (<~5°) to provide best matched availability duration with science target

● Assume Ncomp= 30 then Ntotal = 31x2=62 postage stamps

○ With on-board drift correction data rate is 120 kb/day/star = 7.44Mb/day

○ With no drift correction data rate is 240 kb/day/star = 14.9Mb/day

Keeping 5s frames (unstacked) to use for calibration, gives ~1.7GB/day (uncompressed)

Aitoff projection showing LCAM FOV for December 1, 2024. Blue points mark known exoplanet host stars with 4<Vmag<6.5, and red boxes mark potential comparison stars with 4<Vmag<6.5.

Exoplanet Host Campaign Mode

Campaign Mode:

● Assume side nodding enabled to ‘follow’ high priority targets

○ ~130h (5.5d) of data per lunar day.

→ total of ~30d of data throughout calendar year.

Campaign Mode examples include:

● HR 858 (host to 3 transiting planets with periods <2 weeks):

○ In L-Cam’s Continuous Viewing Zone (available for a total of 168 days/year), good for testing measurement precision, stacking techniques, calibration. Science cases include TTVs, transit profile analysis, discovery of new planets

● 61 Vir: RV exoplanet host P~4d

Aitoff projection showing LCAM FOV for December 1, 2024. Blue points mark known exoplanet host stars with 4<Vmag<6.5, and red boxes mark potential comparison stars with 4<Vmag<6.5.

Asteroids in Stationary ModeGoal: How many asteroids could we observe with LCAM assuming a static telescope

Source: center FOV (Landing site:83° South, 0° East), use of SKYBOT to find asteroids in 20 deg x 24 deg with a time step of 30 min

How: Selected Targets assuming V < 18, using ephemeris of 1.1 million of known asteroids

Asteroid Pop. Number of targets

Average Visual Magnitude

Average max obs. Time (minutes)

Average Number of rotations

Average spin rate (hours)

Max exposure time (8”/12”) (min) in avg

Hungaria 6 17.5 60 9.53 86.66 10/15

Trojan 5 17.12 36 8.7 88.53 21/32

Mars-Crossers 14 16.89 47 9.1 22.97 12/19

Main-Belt 560 16.88 90 7.5 26.50 20/30

NEAs 6

Number of Passing Through Main-belts w.r.t MagnitudeV<11 V<12 V<13 V<14 V<15 V<16 V<17 V<18

1 3 7 19 44 87 202 631

Asteroids in Targeted ModeNEAs FlybyGoal: Astrometry & Spin/Shape/binarity of NEAsTargets: Every month 1 NEA with < 15.5 + NEA candidates recently discovered (a few days before)How: Two stages: 3 full frame images (separated by 30 min-1h). Identification, astrometry, orbit calculation by MPC, then photometry if needed from a stamp (see Stationary mode)Remaining Questions: astrometric accuracy? relative photometry or absolute photometry?

Mutual Events in Multiple SystemsGoal: Detect mutual events between asteroid moons to refine the orbit and detect non-keplerian perturbations (V<12 targets)How: Continuous observations of the multiple system for 3 period of observations (so ~30h) (stamp)Remaining Questions: relative photometry or absolute photometry?

Simulation of a flyby observed with LCAM?

Near-Earth Asteroids in Targeted ModeGoal: How many NEAs are observable, astrometry, spinning period and shape

Source: ephemeride calculation for 20,000 known NEAs during the mission duration

How: Selected Targets assuming V < 16, Elongation > 20 deg, observability (sun, elevation > 17 deg)

Number of Passing Through NEAs w.r.t Magnitude & Number of NEAs observable considering the alt>10 + Sun

mag V<14 V<15 V<16

Number of NEAs

16 40 88

Observable NEAs

5 unk. unk.

Average Rate = 1.92 (arcsec/min)

List of observable NEAs with V< 14

ID & Name P (hrs) V Time observable

488 Eros 5.27 13.3 1080 (hrs)

4954 Eric 12.05 11.01 288 (hrs)

66146 1998TU3

2.37 12.1 264 (hrs)

363027 1998 ST27

unk 13.2 24 (hrs)

439437 2013 NK4

unk 13.9 72 (hrs)

Unknown NEA - some ideas

- Simultaneous observations with NEO Surveillance Mission- Observations nearby the sun. Is there any scientific advantage -> yes to search

for incoming asteroids missing by classical surveys on Earth-

Potential for Discovery

- Can observe objects in daytime sky from Earth- TESS and K2 target follow-up to refine ephemeris on bright ecliptic stars

- How close can we observe from the sun -> NEA search & follow-up?- Support from the ground through a citizen science program (Unistellar and

others)

Backup slides

Exposure time calculations (Magnitude ranges)

SNR=3

SNR=3

SNR

Survey of Asteroids in Stationary Mode

Goal: lightcurve for spin period & shape model inversionTargets: 231 asteroids without a spin period, 10 long-period asteroid (>20 h)How: photometry from a stamp around the asteroid predicted position. On-board ephemeris to identify the location of the asteroid in the FOV is needed. Photometric accuracy <0.1 magRemaining Questions: relative photometry or absolute photometry? Frequency of the observations (ideally 3 full rotation, 20-40 data points)

Lightcurve of 1999 AP10 and fit using Lightcurve inversion algorithm

Reconstructed shape of NEA 1999 AP10 obtained combining archive data and small telescope observations (81 lightcurves of more than 1h taken on 1 month) leading to Pspin = 7.9219 h, pole orientation and shape.

Ligh

tcur

ve in

vers

ion

Magnitude Error