Probe To 'Look Inside' Asteroids

A new space mission concept unveiled at a Paris conference aims to look inside asteroids to reveal how they are made. Deep Interior would use radar to probe the origin and evolution of two near-Earth objects less than 1km across.

The mission, which could launch some time later this decade, would also give clues to how the planets evolved.

The perceived threat of asteroids colliding with our planet has renewed interest in space missions to understand these mysterious bodies.

Deep Interior would use two 30m-long radar antennas to build up a picture of the structure of the asteroids, including compositional boundaries and faults, and its topography.

This should show whether the asteroids are solid all the way through or are essentially floating piles of rubble.

It is intended to rendezvous with two asteroids which are each under 1km in size: Nyx and 1999 ND43.

Nyx is a so-called V-type asteroid, containing stony irons, chondrites and pyroxene. The other target, 1999 ND43, is not well understood.

The probe would also carry a radio tomography instrument - to examine electromagnetic properties - and two colour cameras.

A proposal for the project, described here at the Committee on Space Research (Cospar) scientific assembly, was submitted to Nasa two weeks ago.

The scientists behind the concept hope that, if accepted, the probe could launch as early as 2009.

An asteroid mission concept - called Don Quijote was recently given priority over five other potential asteroid projects by the European Space Agency.

The mission is designed to help scientists understand how an asteroid on a collision course with Earth might be destroyed or deflected.

This mission would involve two spacecraft - Sancho and Hidalgo - launched on different trajectories to the same asteroid. Sancho would arrive first and orbit from a safe distance.

It would then measure the effects as Hidalgo is sent crashing into the asteroid's surface.

Nasa has a similar mission - Deep Impact - which will blow a hole in the comet Tempel 1 and measure the effects.

More Moons Around Earth? It’s Not So Loony
by Robin Lloyd
October 29 1999 -- Earth has a second moon, of sorts, and could have many others. Cruithne, the 3-mile-wide (5-km) satellite, takes 770 years to complete a horseshoe-shaped orbit around Earth, and will remain in a suspended state around Earth for at least 5,000 years. Every 385 years, it comes to its closest point to Earth, some 9.3 million miles (15 million kilometers) away. Its next close approach to Earth comes in 2285. "We found new dynamical channels through which free asteroids become temporarily moons of Earth and stay there from a few thousand years to several tens of thousands of years," said Fathi Namouni, one of the researchers, now at Princeton University. Namouni’s colleague Apostolos Christou said, "At specific points in its orbit, it reverses its rate of motion with respect to Earth so it will appear to go back and forth." In his view, there are three classes of moons – large moons in near-circular orbits around a planet, having formed soon after the planet; smaller fragments that are the products of collisions; and outer, irregular moons in odd orbits, or captured asteroids like Cruithne. In the past year, astronomers have reported finding such objects around Uranus.

Perhaps the most significant development of this line of research will be the finding that such objects also wind up following these same channels to plummet through the atmosphere and wreak havoc.

V.A. Firsoff (Valdemar Axel Firsoff, as it turns out) wrote a lot of books (I think he's dead, but perhaps not), including Strange World of the Moon published back in 1959, ten years before the manned landings started, and even before the first robotic landers.

A while back I picked up a used copy for $1.98 at the enormous chain bookstore, which had "Shimon Kaplan, Israel" on the flyleaf, or whatever that blank first page is called. Hard to figure, considering this is Grand Rapids Michigan, but it's not exactly like a message in a bottle.

Firsoff's book is interesting in that it shows the prevailing ideas about what would be found on the Moon (it was already believed during the 19th century, and more relevantly, by the 1920s and 1930s in Germany, that humans would visit the Moon). In a chapter "The Earth's Fair Child or a Foundling?" Firsoff blows off the idea that impact plays any role on the Moon, attributing its surface features to vulcanism, a view that died a quiet death in 1972, when a geologist first set foot on the Moon.

Due to his volcanism bias, which was an outgrowth of his uniformitarian bias, he wasn't able to accept that the Moon's impact craters were in fact from impact, and attributes them instead to the Moon's capture by the Earth (as well as contraction of the lunar sphere), apparently after having been tossed off by the overspin condition very early in the history of the Earth (see Thomas Van Flandern for a similar articulation). He appears to envisage three encounters between the formed Moon and the Earth, resulting in temporary capture twice leading to the eventual outright capture.

...the Moon clearly could not have been the satellite of the Earth then, for a total period of about 2,000 million years... Spurr points out that the face of the Moon shows two systems of great surface fractures, or faults, lying about 30 degrees from the two poles and trending from west-south-west to east-north-east. This is explained by him as a result of the halting of the Moon's rotation... Curiously, the face of the Earth, too, shows a similar structure, with the same general trend -- the Highland Boundary Fault... The poles of the Earth would also seem to have shifted place on at least three occasions, in the Cambrian, Permian, and (lastly) Quaternary Periods, brining ice and cold to previously warm lands... some mighty force made the crust of the Earth slip (the rotational stability of the axis of a mass as large as the Earth is enormous) and the position of the poles wobbled... there exists on the Moon a triple grid of surface fractures... perpendicular to each other within each grid, the grids being of different ages... Cambrian, Perm-Carboniferous, and Tertiary.

Fascinating idea, based though it is on outmoded ideas about impact (i.e., Firsoff's view that there was no role for impact). He's basically given us a snapshot of the problems inherent with a fission origin (either by overspin or by impact), not least of which is that the fission origin also requires in orbit formation of the lunar sphere and capture by the Earth, while showing that capture is possible.

Here's Van Flandern's book (revised edition). FWIW, I don't agree with him regarding the origin of the moon, wonder how the EPH is an apparently frequent phenomenon while TVF provides no mechanism, and most notoriously, wonder how and why he remains a supporter of Richard Hoaxland's "face on Mars" nonsense:

Dark Matter, Missing Planets and New Comets:
Paradoxes Resolved, Origins Illuminated
by Tom Van Flandern

currently-prevailing theory was that a mars size planet impacted the primordial earth early on, and that the moon was formed of the debris.

I'm very interested in impact, but there's no way for this impact scenario to be credible, even without bringing in the fossil evidence which shows it didn't happen. The impact model is not only impact, but also capture, as well as in-orbit formation. IOW, it's three models in one. Other than the impact advocates (and yes, they are legion), I don't know of any in-orbit formation advocates (that was once a viable model with a number of adherents).

And as long as we're talking asteroids and comets let us just keep in mind that the spectacular battering that marked the moon also happend to earth, it's just that earth dynamic system swallows, buries, grinds away, etc. it's scars so much better.

Yes, but that hasn't anything to do with the impact model for lunar formation. The hypothetical impact would have made the entire Earth molten again (provided the surface had yet cooled), and the infalling debris from the impact (it wouldn't be like knockin' out a divet, the ejecta would go every direction) would have created craters. But, that's not where the craters came from, because there was no such event. Mars' craters were in some large part formed in a single impact event, but the rest were single or doublet impacts.

The recent book Rare Earth dedicates one of it's chapters to the crucial role the moon (among many other factors) has played in making the earth hospitable for life.

The authors try in that book to build a case for the uniqueness of the Earth and for life on Earth, grinding some political axe. To them, every little characteristic of the Earth that they care to include adds up to the impossibility of life elsewhere. Since the Moon hasn't always been a satellite of the Earth, what they say about it has no bearing on anything. For that matter, not much in that book is worth mentioning.

Cordially...

'Civ, who sez: George W. Bush will be reelected by a margin of at least ten per cent

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