Farside offers radio-quiet to probe cosmic Dark Age

Dark Ages Radio Explorer (DARE), utilizing the radio-quiet of the lunar farside to explore the earliest period on the cosmic time line, 200 million years between the primordial Big Bang and the emergence of the earliest luminous sources and the structure of the present universe. "The lunar Farside is potentially the only site in the inner solar system for high precision radio cosmology.” [NLSI].

Anil Ananthaswamy
New Scientist
 
FORTY years after NASA ditched the idea of landing Apollo 17 on the far side of the moon, the forbidden fruit is being sought once again. Not by astronauts this time, but by astronomers seeking a quiet spot from which to observe the universe's "dark ages".

This was an epoch in the development of the cosmos, which lasted for a few hundred million years after the big bang, before stars and galaxies began to form. The only way to observe the dark ages is to look for faint radio signals from neutral hydrogen - single protons orbited by single electrons - which filled the early universe.

Telescopes on Earth, such as the Murchison Widefield Array in Western Australia, are searching for such signals, at frequencies above 100 megahertz. This can probe the universe back to 400 million years after the big bang.

To explore even earlier times, telescopes need to receive radio waves at frequencies below 100 megahertz. Interference from radio sources on Earth such as FM radio and the planet's ionosphere can mess up these signals. "You get to the point where the ionosphere is just a hopeless barrier," says Dayton Jones of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. "You have got to go to space, and the most promising location by far is the far side of the moon."

To peer back to the universe's earliest years will need sensitive telescopes in a place where Earth's ionosphere and radio chatter cannot interfere

This is why astronomers were discussing it at an American Astronomical Society meeting in Anchorage, Alaska, this month. Telescopes behind the moon would not have to contend with Earth's ionosphere, and they would also be shielded from our planet's radio chatter. "It is a very pristine environment for low-frequency observation," says Jones.

The first shot at radio astronomy from the moon's far side will probably be a mission called the Dark Ages Radio Explorer, being designed by Jack Burns at the University of Colorado at Boulder, and colleagues.

If selected as a mission by NASA in its review next year, DARE will orbit the moon at an altitude of 200 kilometers. It will collect neutral-hydrogen signals between 40 and 120 megahertz. That corresponds to 80 million to 420 million years after the big bang. Its antenna is designed to pick up signals from the entire sky. The craft will be a little toughie, with parts made from an Astroquartz/Kevlar fibre, which is very thermally stable - particularly handy when moving in and out of sunlight as it orbits the moon.

The DARE team has begun testing the probe's antenna at remote locations on Earth, starting with the National Radio Quiet Zone surrounding the Green Bank telescope in West Virginia. "It may be a radio quiet zone, but it's not quite," says DARE team member Abhirup Datta. "You can still see the FM bands coming in, and of course the ionosphere is a problem."

Not everyone reckons a space-based solution is needed to study the universe's dark ages. "Existing ground-based experiments will yield good progress on this problem at a tiny fraction of the cost of a space mission," says Steven Tingay of Curtin University in Bentley, Western Australia, who headed the construction of the Murchison array.

Burns disagrees. Preliminary tests reveal that the Earth's ionosphere is absorbing signals from space and re-emitting them as noise in frequencies below 80 megahertz. "If we can verify and characterize that, that slams the lid on any attempts to do this kind of experiment from the ground," says Burns.

Once DARE has done its job, his team want to deploy bigger telescopes on the lunar far side to image the first stars and galaxies. These antennas would be made of conducting material imprinted on extremely lightweight films of polyamide, micrometers thick.

In one design, three 100-metre-long arms of such films are attached to a central box of electronics. The arms would be rolled up tight for launch and, once on the moon, a rover sent along with the unit will move it to its required spot and help unfurl the arms. The rover would likely have to be controlled by astronauts orbiting a Lagrange point over the lunar far side.

To test this scenario, Burns's team will work with astronauts based on the International Space Station next year. The astronauts will remotely operate a Mars rover called K-10. It is being outfitted to unwind films of polyamide on a simulated Martian landscape at NASA Ames Research Center in Moffett Field, California.

HDTV still of Tsiolkovskiy, captured by Japan's lunar orbiter SELENE-1 ("Kaguya," 2007-2009). The Naval Research Laboratory, Massachusetts Institute of Technology and  others are refining work on a possible radio telescope array to be deployed in the conspicuous farside crater floor to utilize the radio quiet of the the Moon's farside to probe the cosmic Dark Age [JAXA/NHK/SELENE].

"The ultimate experiment we'd like to do for cosmology on the far side would involve thousands of these antennas," says Burns.

But what if the basic idea proves unfeasible, in terms of cost or in overcoming obstacles in the terrain? At JPL, Jones and his team are working on another solution: rolled-up antennas that inflate like party blowers seconds before they touch the lunar surface. "They are essentially immune to whatever irregularities there are at the surface," says Jones.

Astronomers have their sights set on at least one site for such telescopes: the flat bed of the 180-kilometre-wide Tsiolkovskiy crater, exactly where the Apollo 17 astronauts first wanted to land.

Related Posts:

The Moon as a platform for Astrophysics (April 24, 2012)
MIT to lead development of new radio telescope
array on lunar farside (February 19, 2008)
Naval Research Laboratory to design Farside DALI (March 11, 2008)
What better view? (March 26, 2008)
New model of lunar motion from Apollo LLRR (December 27, 2008)
MacDonald LLR defunded by NSF (June 21, 2009)
The continued importance of lunar laser ranging (August 3, 2009)
Laser Ranging and the LRO (August 12, 2009)
Dust accumulation on Apollo laser reflectors may
indicate a surprisingly fast and more dynamic
lunar exosphere (February 16, 2010)
Long term degradation of optics on the Moon (March 4, 2010)
A Fundamental Point on the Moon (April 13, 2010)
Acquisition Lunokhod-1 (April 27, 2010)

The Moon as a platform for astrophysics

Darks Ages Radio Explorer (DARE), utilizing the radio-quiet of the lunar farside to explore the earliest period on the cosmic time line, 200 million years between the primordial Big Bang and the emergence of the earliest luminous sources and the structure of the present universe. "The lunar Farside is potentially the only site in the inner solar system for high precision radio cosmology.” [NLSI].

Joel Raupe
and from reports

The Moon has been used as a platform for astrophysics research since laser range reflectors were deployed by three of the six Apollo surface expeditions and also as part of the Soviet two Lunokhod robotic rovers. A lunar laser range reflector (LLRR) has now been orbiting the Moon as part of the Lunar Reconnaissance Orbiter (LRO) mission since June 2009.

A welcome added bonus to the LRO mission came after photographing Lunokhod-1. The 1970 mission's French-built LLRR had been lost almost immediately after the rover was parked for the last time in 1970.

Before LRO, with only four arrays bouncing back mere photons from powerful laser pulses from Earth beginning in 1969, the distance to the Moon was measured with increasing accuracy down to a 3 centimeter margin of error. With the addition of the LRO reflector and after definitively locating Lunokhod-1 astrophysicists sharpened  measurements even further, finally with precision enough to rule out the idea that the astounding newly discovered increasing rate of the universe's expansion might be a “local” phenomenon, or a kind of optical illusion.

The Naval Research Laboratory (NRL), together with the Massachusetts Institute of Technology (MIT), has been building on the age old dream of utilizing the “radio quiet” of the Moon’s Farside to peer into the elusive Cosmic Dark Age, the period between the Big Bang and the “Epoch of Reionization,”  when an intergalactic medium composed mostly of neutral gases was “ionized by the emergence of the first luminous sources.”

Continuing with this description supplied by the MIT Haystack Observatory, “The sources may have been stars, galaxies, quasars, or some combination.  By studying  Reionization we can learn a great deal about the process of structure formation in the Universe, and find the evolutionary links between the remarkably smooth matter distribution at early times revealed by (Cosmic Background Radiation) studies and the highly structured universe of galaxies and clusters of galaxies” astronomers can peer more than 10 billion light years into the past.

Exploring that early “Dark Age” will almost certainly require radio telescopes able to detect sources radiating at frequencies red-shifted to wavelengths typical of the noise created by human civilization.

A solution offered by MIT and the NRL suggested an immense antenna farm deployed robotically on the wide floor of Tsiolkovskiy crater. The Dark Age Lunar Interferometer array was discussed in some detail in 2008, when achieving “extended human activity” on the Moon was national space policy.

The NASA Lunar Science Institute (NLSI) reports two of their collaborating working groups are suggesting putting a radio telescope in orbit around the Moon where it can put a significant part of its time exploring this cosmic Dark Age, the Darks Ages Radio Explorer (DARE). The mission concept is one of two ideas being pursued by the Lunar University Network for Astrophysical Research (LUNAR) “addressing the question of how the Moon can be used as a platform to advance important goals in astrophysics,” according to the NLSI.

The other suggestion by the LUNAR group proposes, “technology development for future lunar surface telescopes, which can help detect and characterize Earth-like planets orbiting nearby starts.

“Both approaches leverage the Moon as a science platform. The lunar Farside is potentially the only site in the inner solar system for high precision radio cosmology.”

DARE will use the highly-redshifted hyperfine 21 cm transition from neutral hydrogen to track the formation of the first luminous objects by their impact on the intergalactic medium during the end of the Dark Ages and during Cosmic Dawn. The science instrument is composed of a low frequency radiometer, a receiver, and a digital spectrometer. The various sub-systems have been constructed and are in the process of system integration. After check-out, the system will be deployed and tested at the Murchison Radio Observatory in Western Australia—one of the most radio quiet locations on the planet.

The Lunar Radio Telescope Array (LRTA) is a concept for a telescope located on the far side of the Moon where it is protected from radio frequency interference (RFI). It would detect magnetically generated radio emissions to provide insights into the interior structure of planets— information likely to be difficult to obtain by other means.

The Apollo 15 laser ranger reflector, 4x the area of
the LLRR arrays deployed by Apollo 11 & 14, is
the most reliable of the 5 units placed on the Moon.

Furthermore, the Lunar Laser Ranging (LLR) component of the LUNAR team has taken a two-fold approach toward testing theories of gravity. Not only are they continuing precise measurements of the Earth-Moon distance via laser ranging, but they are also leading efforts to develop a next-generation retroreflector package that could be emplaced on the Moon by future missions.

While the three retroflector arrays deployed during Apollo era were an incredible success, the reduced return from the arrays over the years has limited advanced investigation into general relativity. At present, there are a number of stations that can access Apollo 15 arrays but not the Apollo 11 and 14 arrays; the new retroreflectors will have signals that can be accessed by a large number of lunar laser ranging ground stations. A next generation retroreflector would improve precision measurements for gravitational physics and for understanding the lunar interior.

As a classical theory, general relativity and quantum mechanics are fundamentally inconsistent; there must be a breakdown at some level of accuracy in general relativity or a problem with quantum mechanics. A much higher ranging accuracy would improve scientific results in testing the theory of general relativity by more than two orders of magnitude. 

This post was derived in part from the NLSI release,
NLSI Teams Conduct Astrophysics Research

Related Posts:
MIT to lead development of new radio telescope
array on lunar farside (February 19, 2008)
Naval Research Laboratory to design Farside DALI (March 11, 2008)
What better view? (March 26, 2008)
New model of lunar motion from Apollo LLRR (December 27, 2008)
MacDonald LLR defunded by NSF (June 21, 2009)
The continued importance of lunar laser ranging (August 3, 2009)
Laser Ranging and the LRO (August 12, 2009)
Dust accumulation on Apollo laser reflectors may
indicate a surprisingly fast and more dynamic
lunar exosphere (February 16, 2010)
Long term degradation of optics on the Moon (March 4, 2010)
A Fundamental Point on the Moon (April 13, 2010)
Acquisition Lunokhod-1 (April 27, 2010)

Spudis flies with Chandrayaan

Noted planetary geologist Paul Spudis has been named as Principal Investigator for one of two American instruments on their way to the Moon on-board Chandrayaan 1.

The Indian Space Research Organisation's (IRSO) Lunar orbiter passed a 150,000 km Earth orbital apogee, Sunday, already higher than any spacecraft launched by India. Eight nations are participating in a suite of eleven remote sensing instruments on Chandrayaan's mission.

Chandrayaan 1 was successfully launched from Sriharikota, on the southeastern coast of the Sub-Continent, October 22.

Spudis is the immediate-past director of the USRA's NASA-chartered Lunar and Planetary Science Institute in Houston.

Spudis is now PI for the team, headed by Johns Hopkins Applied Physics Research Laboratory and the Naval Research Laboratory, that designed and built the Mini Synthetic Aperture Radar (MiniSAR), imaging radar to map the Lunar poles. MiniSAR will map the permanently-shadowed abyssal craters and valleys at the highest lattitude, in search of water ice and other volatiles.

"This has been a controversial area of investigation for the last decade," explained Lunar and Planetary Institute Director Dr. Stephen Mackwell, "The inclusion of the MiniSAR instrument in the Chandrayaan-1 mission will allow us to collect information on these deposits by mapping them from an instrument in lunar orbit - a first in the exploration of the moon."

U.S. missions Clementine (1994) and Lunar Prospector (1998) both detected the unique signature of Hydrogen, in and around both Lunar poles, with Neutron detectors designed to separate elemental signatures resulting from the spillation of Cosmic Rays breaking about on and immediately below the Moon's surface.

The public release, last week, of images inside Shakelton Crater, taken from the Terrain Camera on-board Japan's Kaguya reportedly eliminated the likelihood of ice at the Lunar poles, but most planetary scientist were not surprised by the images. Few were expecting any water ice there to be immediately visible, in the form of snow or a frozen pond. Most believe what volatiles or water ice there might be at the Lunar poles to be buried or well-mixed with dusty regolith.

Hydrogen and other "volatiles" cannot freely range on the lunar surface, and since the Apollo Era the Moon has been considered among "the driest places in the Solar System."

The Moon's "exosphere," however, has since been interpreted as very dynamic, rather than static. The constant rain of cometary water ice and charged particles are thought to literally shatter and bounce all over the Moon, some of it coming to rest in the dusty "Cold Traps," permanently shadowed from disbursing by proton-packed Solar Wind.

Over a four and a half billion year history, the Moon's manifest history of impacts large and small is thought to have gathered many tons of volatiles in these Cold Traps.

NASA's Long-term plans call for a semi-permanent manned presense on the rim of Shackleton Crater, overlooking the 20 mile wide, permanently darkened interior, where some portion may have naturally stored the stuff that both life and rocket fuel are made of.

Spudis, as both a scientist and director, has been closely associated with Lunar and Martian science for thirty years. An penultimate "multi-tasker," Spudis has probably forgotten more about the Moon than most NASA directors will ever know.

Popular Science: More on Athlete

The Lunar Habitat Hauler

Popular Science Online has posted perhaps the best, well, "popular" close up look yet at Athlete, under going testing at JPL. A featured video shows off more nifty detail of what is certain to become an iconic and integral part of NASA's nomadic lunar exploration paradigm, now being shown-off to the general public.

Annemarie Conte posted the close-up video presentation at PopSci Tuesday afternoon, April 22.

"The mission-ready robot," she writes, "which will be about twice the size of the prototype pictured here and made of steel, should be able to haul a load of up to 15 tons pretty much anywhere it wants to—as long as it obeys a 3mph speed limit. “That’s about as fast as you can go without risking flipping over because of the low gravity,” explains Brian Wilcox, the primary investigator on the Athlete project...."

"Scientists at JPL hope to rocket Athlete to the moon for unmanned testing as early as 2012. What would come next depends on the success of NASA’s plans for manned space exploration"

Read more HERE.

Athletic Teamwork

More excellent YouTube video of Naval Research Laboratory's Athlete in action, cooperating in heavy lifting

More on NRL's Lunar Athlete Rover

While I've written before of the U.S. Navy's Athlete, a dexterous, long distance and freight-handling robotic walking lunar rover, under development by the Naval Research Laboratory in cooperation with the Massachusetts Institute of Technology, I thought I'd be reading of something quite different when teased by a passing headline a short time ago.

The Athlete test-bed robots are gangly-looking enough, I thought, than to read New Scientist describe them as "giant, six-legged robots," that can "pick up and move a future Moon base thousands of kilometres across the lunar surface.."

They're certainly big, but hardly the 50 Foot Woman, not able to to lift a single-wide mobile home, let along an entire moon base, except perhaps in pieces and many trips.

And whether they are able to handle "thousands of kilometers" even over the course of any one unit's lifetime remains to be seen.

Athlete has been developed with MIT's farside Dark Age Lunar Interferometer, or DALI, which the Institute hopes can be deployed over a thirty-five mile wide area of the Tsiolkovsky, and in relative radio quiet a decade from now. DALI would listening for faint, highly red-shifted wavelengths from the so-called Dark Age, between 200 million years after the Big Bang and the first eras of star formation hundreds of millions of years later, when the structure of the present state of the known Universe began.

As I posted previously, the Naval Research Laboratory shares a $500,000 grant with MIT to design and test the logistics of deploying the proposed array. Plans call for deploying a nearside radio array to perform some actual science and to test the concepts behind DALI and its construction, already well along in planning.

NRL proposes using Athlete to patiently and persistently, as a robot should, haul components from a landing zone and eventual hub to sites clustered over a 50 kilometer wide area in Tsiolkovsky's southeastern third.

Each collector, 250 meters in size, would then need to be deployed and tuned. I've suggested they might then become integral to the full array itself by offering tuning mobility as the rails for the Very Long Baseline Array in Socorro, New Mexico performs, changing the size of a massive virtual aperture.

New Science Robots Special Report

JPL Athlete

AIAA Lunar Architecture (September 2007) - Adobe Reader

Navy shows off the Athletes, Stretches for the Lunar Farside

Construction of the Dark Ages Lunar Interferometer, or DALI, will require a lot a territory, for sufficient baseline to build an antenna to detect even the lowest harmonics of highly redshifted electro-magnetic signals, and there's a need for much "radio-quiet" to pull those signals out from the background noise, for the best signal-to-noise ratio and "gain."

And the Dark Ages Lunar Interferometer will need both to detect the altogether faint signals of, well, whatever one might find in the darkness between the Realm of the Blue Galaxies - the very limit of optical telescopy and still on our side of the cosmic microwave hiss of just three degrees above absolute zero - all that remains of the outer edge of the Big Bang, when "nothing became everything."

The Cosmic Dark Ages have something to tell us, but they exist only in the fossil sky and from a period before the first stars formed. It is truly a dark age, and JPL would like to change this. And one Prime Reason for a return to Earth's Moon is made manifest, because it is a natural platform for the largest telescopes imaginable, and these idea are taking shape sooner rather than later.

The construction of the DALI, a sea of "cellular" detectors spread over a huge are, will be, developers say, robotic. A trick, on the Farside, depending on interminent communication and exceptionally hardy robots, of course.

The Lunar Farside has both "radio-quiet" and territory, in abundance, or NASA's Jet Propulsion Laboratory in Pasadena hopes so, and for the moment anyway.

The U.S. Naval Research Laboratory showed off its Athletes, recently, and not for the Beijing Olympics. These Athletes look ready for uncomplaining work deploying MIT's design for a very, very, very long baseline interferometer in the Sea of Tsiolkovski, named, of course for the Russian school teacher who dreamed and discovered a "method of achieving extreme altitude," in awe, "to lift, by hand, a rock from the moon," and, in the next sentence, "the earth is the cradle of the mind, but one cannot live forever in a cradle."

It's an excellent first look. From DVICE.com (powered by SciFi )

See also "Naval Research Laboratory to design Farside DALI," March 11, 2008

Naval Research Laboratory to design Farside DALI

The Dark Age Lunar Interferometer (DALI) apparently planned for multi-robot deployment from Tsiolkovsky

Contact: Donna McKinney
(202) 767-2541
Naval Research Laboratory

A team of scientists and engineers led by the Naval Research Laboratory (NRL) will study how to design a telescope on the Moon for peering into the last unexplored epoch in the Universe’s history. NASA has announced that it will sponsor a series of studies focusing on next-generation space missions for astronomy. These studies will contribute to the Decadal Survey, an effort undertaken every 10 years by astronomers and physicists to help establish priorities for future research directions in astronomy and astrophysics. The upcoming Decadal Survey occurs over the next two years.

Among the missions to be studied is the Dark Ages Lunar Interferometer (DALI), the NRL-led concept for a telescope based on the Moon and studying an era of the young Universe, during the first 100 million years of its existence. Although the night sky is filled with stars, these stars did not form instantaneously after the Big Bang. There was an interval, now called the “Dark Ages,” in which the Universe was unlit by any star. The most abundant element in the Universe, and the raw material from which stars, planets, and people are formed, is hydrogen. Fortunately, the hydrogen atom can produce a signal in the radio-wavelength part of the spectrum, at 21 cm; a wavelength far longer than what the human eye can detect. If these first signals from hydrogen atoms in the Dark Ages can be detected, astronomers can essentially probe how the first stars, the first galaxies, and ultimately the modern Universe evolved.

Because the Universe is expanding, the signals from these distant hydrogen atoms will be stretched (or redshifted) to much longer wavelengths, as large as several meters. While astronomical observations at radio wavelengths have a long history, this portion of the electromagnetic spectrum is now heavily used for various civil and military transmissions, all of which are millions of times brighter than the hydrogen signal that astronomers seek to detect. Additionally, the upper layers of the Earth’s atmosphere are ionized (the ionosphere), which introduce distortions into astronomical signals as they pass through on their way to telescopes on the ground.

With no atmosphere and shielding from the Earth, the far side of the Moon presents a nearly ideal environment for a sensitive Dark Ages telescope. In NRL’s DALI concept, scientists and engineers will investigate novel antenna constructions, methods to deploy the antennas, electronics that can survive in the harsh lunar environment, and related technology in preparation for developing a roadmap for research and development of a lunar telescope over the next decade. The team will also build on their experience in developing the Radio Observatory for Lunar Sortie Science, a NASA-funded study of a pathfinding array that would be located on the near side of the Moon.

The project leader at NRL, Dr. Joseph Lazio, pointed out that DALI will be one of the most powerful telescopes ever built and will bring us closer than we have ever been to understanding where our Universe came from and where it is going. “Probing the Dark Ages presents the opportunity to watch the young Universe evolve,” Dr. Lazio said. “Just as current cosmological studies have both fascinated and surprised us, I anticipate that DALI will lead both to increased understanding of the Universe and unexpected discoveries.”

When asked about the program, NRL Senior Astronomer Dr. Kurt Weiler remarked: “Building telescopes on the Moon is clearly a long-term project, but I am very excited about us getting started on this proposal.”
###
Scientists and engineers from institutions and NASA centers around the country are participating in the Dark Ages Lunar Interferometer study, including NASA/Goddard Space Flight Center, Caltech/Jet Propulsion Laboratory, the University of Colorado, the Smithsonian Astrophysical Observatory, the National Radio Astronomy Observatory, University of California-Los Angeles, University of California-Berkeley, the University of New Mexico, and Virginia Polytechnic Institute and State University (VA Tech).