Space scientist suggests mission to Venus might help explain origin of the Moon

Dec 05, 2013 by Bob Yirka report
The Moon's gravity field as mapped by NASA's Gravity Recovery and Interior Laboratory. Credit: NASA/JPL-CALTECH/MIT/GSFC

( —Robin Canup, a space scientist with the Southwest Research Institute in Colorado has published a Comment piece in the journal Nature proposing that a mission to Venus be considered to help better understand the development of our moon. She suggests that current theories that describe how the moon came about rely too heavily on Mars data, which could be obscuring the real story. Tim Elliot and Sarah Stewart offer their own opinions on the matter in a companion News & Views piece in the same journal.

The general consensus among modern space scientists is that our moon came to exist as the result of a Mars size planet impacting the Earth—that impact, the thinking goes, would have caused a lot of debris (made up mainly of material from the impactor) being pushed into space which over would have coalesced over time into a disk and then eventually, into the moon as we know it today.

The problem with this theory, as Canup notes, is that evidence is mounting that indicates the moon, at least on its surface, is far more like the Earth than the theory suggests. Silicate samples brought back from manned missions, for example have the same isotope composition as those found here on Earth. It's possible the impacting body had a nearly identical composition to the Earth, but that seems unlikely considering the differences in composition between Earth, and say Mars. That's part of the reason Canup argues, that we need to go to Venus. We don't have isotopic samples from that planet. If we did go there and retrieve samples and then found them similar to those here on Earth, it would go a long way towards explaining why the Earth and Moon seem to be so similar.

Meanwhile, space scientists are left to consider other theories to explain not just how the moon was created and developed but how it and the Earth evolved together resulting in the relationship we have today. Some have suggested that perhaps the impact was actually between two Earth-like bodies, or maybe, the Earth was spinning a lot faster way back when which would have resulted in a small impact causing a lot of Earth debris to be flung into , leading to the formation of the moon.

The main point Canup seems to be making is that if we want to understand our own planet better, we need to understand the as well. And to do that, we need more data—starting with surface samples from Venus, she notes, would be a great way to begin.

Explore further: Water hidden in the Moon may have proto-Earth origin

More information: Planetary science: Lunar conspiracies, by Robin Canup, Nature 504, 27–29 (05 December 2013) DOI: 10.1038/504027a

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4 / 5 (4) Dec 05, 2013
Composition notwithstanding, the relative confinement of the post-impact debris to a comparatively low earth orbit suggests a highly inelastic collision with low impact velocity (compared to that of a body from the Oort cloud). A horseshoe orbit for 'Theia', formed simultaneously with Earth at about the same distance from the sun at a Lagrange point, would account for a lot.
3 / 5 (2) Dec 05, 2013
Or maybe the surface of the Earth is made of the other half of the impactor. Not all of the debris would have stayed in orbit, and if the rest fell back to Earth, it would logically be on the surface. What we see as "normal" Earth composition may not be truly representative of the primordial Earth.
1 / 5 (7) Dec 06, 2013
Sub: Space baby Concept
Sun and Moon are two lobes and a netral element takes over to guide Humanity.The orgins-Space Cosmology Vedas -see my projections in books-help to evolve Human being Sensex.
an index is essential for knowledge base creation.
I have projected details in my Talk at COSPAR-2013, Nov 13, Bangkok
1. NANDI introduces new concepts for flow-fields integration
2. Super-imposition of Visible -Invisile matrix mode over space based observations
1 / 5 (2) Dec 06, 2013
Perhaps the moon is made of the same material as the Earth, and the collusion theory is not correct? Good luck getting samples from the surface of Venus.
3.7 / 5 (3) Dec 06, 2013
dobermanmacleod: That's why we need more samples. There are viable theories that say they did form together, but they fail on angular momentum calculations. If Earth and Venus are similar enough, the impact theory will be strengthened. If Venus is as different from Earth as Mars is, it's unlikely the impactor was similar to Earth, and the other theories look better.

Yes, getting samples back from Venus will be a challenge. Not nearly as simple as the Moon, or even Mars.

vidyunmaya: ????????
1 / 5 (1) Dec 09, 2013
Hold on here.

There was a consensus among scientists for the impactor theory, based on computer models.

Now where have I heard that one before? Hmmm...