Jack Burns University of Colorado Boulder and NASA Lunar Science Institute & the LUNAR* Team *Lunar University Network for Astrophysics Research (LUNAR) Science Frontiers Program Prioritization • Cosmology & Fundamental • Radio, Millimeter, and Sub‐ Physics millimeter Astronomy from • Galaxies Across Cosmic Time the Ground • The Galactic Neighborhood • Optical and Infrared • Stars and Stellar Evolution Astronomy from the Ground • • Planetary Systems and Star Electromagnetic Formation Observations from Space • Particle Astrophysics & Gravitation Science Frontiers Space Projects ‐ Large • Discovery (e.g., new technologies, 1. WFIRST observing strategies, theory => transformational) 2. Explorer Program augmentation • Origins (origin & evolution of astronomical objects) 3. LISA • Understanding the Cosmic 4. IXO Order • Frontiers of Knowledge • Building on the science priorities identified by the survey, the recommended program is organized by three science objectives that represent its scope: − Cosmic Dawn − New Worlds − Physics of the Universe • Success in attaining these science goals will enable progress on a much broader front • Also foster unanticipated discoveries

4 New Worlds, New Horizons in Astronomy and Astrophysics “A great mystery now confronts us: When and how did the first galaxies form out of cold clumps of hydrogen gas and start to shine—when was our “cosmic dawn”? Observations and calculations suggest that this phenomenon occurred when the universe was roughly half a billion years old, when light from the first stars was able to ionize the hydrogen gas in the universe from atoms into electrons and protons—a period known as the epoch of reionization. Scientists think that the first stars were massive and short-lived. They quickly exploded as supernovae, creating and dispersing the first elements with nuclei heavier than those of hydrogen, helium, and lithium, and leaving behind the first black holes. Astronomers must now search the sky for these infant galaxies and find out how they behaved and interacted with their surroundings.” No observations currently exist!

z=1100 z=27 z=21 z=13 z=8 z=0 t=400,000 yr t=120 Myr t=170 Myr t=340 Myr t=650 Myr t=13.7 Gyr 21 (1+z) cm = 1420/(1+z) MHz at z=10, λ = 2.3 m (130 MHz) at z=50, λ = 10.7 m (30 MHz) (z=46) (z=13)

RAE-2 1973

Analogous to why COBE went to space • “The Explorer program enables rapid Possible Lunar Explorers responses to new discoveries and provides platforms for targeted investigations essential to the breadth of NASA’s astrophysics program.” • “The promise of future Explorer missions is as great as ever, and this program will be essential to enabling new opportunities, and Dark Ages Radio Explorer (DARE) to maintaining breadth and vibrancy in NASA’s astrophysics portfolio in a time of budgetary stress.” • “This survey recommends that the annual budget of the astrophysics component of the Explorer program be increased from $40 million to $100 million by 2015.”

Lunar Laser Ranging Retroreflector Explorer Ground-based telescopes Lunar Orbit Lunar Farside

EDGES

MWA

LOFAR

New Worlds, New Horizons in Astronomy and Astrophysics “These events lie largely in the realm of theory today and existing telescopes can barely probe this mysterious era. Over the next decade, we expect this to change. A new window on the cosmos is being opened in several wavelengths: Radio astronomers are constructing telescopes that will tell us when and where the first stars in the universe formed by mapping their effect on the primordial hydrogen at the end of the dark ages and are planning those that will be able to directly observe the primordial hydrogen atoms that permeated the dark ages of the universe.” Probing the Ionized Lunar Atmosphere with a Low Frequency Antenna Lunar Ionosphere & Riometry Lead: Joseph Lazio, JPL

• The NRC report The Scientific Context for Exploration of the Moon identifies understanding the “processes involved with the atmosphere (exosphere) of airless bodies in the solar system” as a priority.

• Determining & tracking the properties of the lunar atmosphere both robustly and over time requires a lunar‐based methodology so the atmosphere can be monitored over multiple day‐night cycles from a fixed location(s), such as a lunar relative ionosphere opacity meter (riometer).

Lunar ionosphere electron densities derived from • Riometer exploits this characteristic of a dual‐frequency radio occultation measurements plasma to measure the ionospheric density: during the Luna 19 and Luna 22 missions . 3 1/2 fp = 9 kHz (ne/1 cm ) . An Interplanetary Dust Detector on the Lunar Surface Lead: Justin Kasper, Harvard-Smithsonian CfA • The direct detection of gravitomagnetic effects (e.g., Lense‐ Thirring precession) is from Lageos/GRACE, Gravity Probe B, and Lunar Laser Ranging. • Limits on the fractional rate of change of Newton’s Gravitational constant G (10‐12/yr) from Lunar Laser Ranging. • Strong & weak Equivalence Principle limits. Better determination of PPN and Ġ/G from next generation Lunar Laser Ranging. • “A new Lunar Laser Ranging (LLR) program, if conducted as a low cost robotic mission or an add‐on to a manned mission to the Moon, offers a promising and cost‐ effective way to test general relativity and other theories of gravity.” • “These are tests of the core foundational principles of general relativity. Any detected violation would require a major revision of current theoretical understanding... Because of their importance, the panel favors pushing the limits on these principles… The installation of new LLR retroreflectors to replace the 40 year old ones might provide such an opportunity… context of a recommendation to augment the Explorer program.” LUNAR Efforts to Advance Laser Ranging Recovery of Lunokhod 1 Retroflector with APOLLO Lead: Thomas Murphy, University of California, San Diego

Lunokhod 1 Lander Apache Point Observatory Lunar Laser-ranging Operation (APOLLO)

• Offset was 40 m (270 ns) in projected range (100 m lateral), putting signal at edge of gate. • Potential Science: Offers best leverage on libration determination => key for Center of Mass determination & lunar interior study.

LROC image of Lunokhod 1 site LUNAR Efforts to Advance Laser Ranging Hydroxide Bonding and Hollow Cubes Lead: Stephen Merkowitz, NASA GSFC LUNAR Efforts to Advance Laser Ranging Gas Assisted Drilling Leads: Kris Zacny, Honeybee Robotics Douglas Currie, University of Maryland • One of the key science objectives in Astro2010 Decadal Survey is Cosmic Dawn: “When and how did the first galaxies form out of cold clumps of hydrogen gas and start to shine?” We can uniquely address this mystery with low frequency radio telescopes in lunar orbit (sky‐averaged 21‐cm spectrum) or arrays on the lunar farside (spatial structure in 21‐cm signal).

• Lunar Laser Ranging will “test the core foundational principles of general relativity.” A new generation of retroreflectors emplaced on the lunar surface using gas‐assisted drilling technologies on an Explorer‐class mission “offers a promising and cost‐effective way to test general relativity and other theories of gravity.”