Feeds

NASA probes seek remnants of lost 'Theia' planet

Boffins: Ancient world smashed into us to create Moon

Build a business case: developing custom apps

A pair of NASA "space weather" monitoring spacecraft are having something of a change of pace, as they search for evidence of a long-lost world which may once have crashed into the Earth, and so formed the Moon.

The two probes in question are those of the space agency's Solar Terrestrial Relations Observatory (STEREO) programme, intended to gain a side view of the sun's interaction with Earth.

Animation showing the motion of Jupiter's Trojan and Hilda asteroids

Jupiter's L4 and L5 points are absolutely chocka.

As such, the STEREO space brace are primarily intended for spying out solar storms, sunspots and the like. But they can also do other things, and just at the moment the two craft are passing through the Earth/Sun system's L4 and L5 Lagrange points.

Lagrange points are locations where drifting space objects tend to accumulate, as orbital and gravitational forces combine to hold them there. You get an L4 and L5 point sixty degrees ahead and behind on the orbit of any body orbiting a larger one, in this case with the Earth orbiting the Sun. The animated illustration shows the L4 and L5 points of Jupiter, which stays almost stationary at the top of the picture with two large asteroid clusters (the "Trojans" and the "Greeks") to either side - with so-called "Hilda" asteroids circulating between them, mostly just outside the main asteroid belt. The faster-orbiting Earth is seen near the centre.

In the case of the previously unvisited Earth/Sun L4 and L5 "gravitational parking lots," as NASA calls them, there could be some major stuff to be found.

"These places may hold small asteroids, which could be leftovers from a Mars-sized planet that formed billions of years ago," says NASA's Michael Kaiser. "About 4.5 billion years ago when the planets were still growing, this hypothetical world, called Theia, may have been nudged out of L4 or L5 by the increasing gravity of the other developing planets like Venus and sent on a collision course with Earth. The resulting impact blasted the outer layers of Theia and Earth into orbit, which eventually coalesced under their own gravity to form the moon."

Boffins think the planet-smash theory of lunar formation could explain why the Moon has such a relatively unimpressive iron core, being made up mostly of melted crusty bits smashed off in the possible Earth/Theia pileup and then blobbed together.

"Taking the time to observe L4 and L5 is kind of cool because it's free," adds Kaiser. "We're going through there anyway and we're moving too fast to get stuck. In fact, after we pass through these regions, we will see them all the time because our instruments will be looking back through them to observe the sun."

The STEREOcraft will look for asteroids with wide-field-of-view telescopes that come as part of their solar-corona probing kit. Any asteroid will probably appear as just a point of light, orbiting the L4 or L5 point. It'll be possible to tell if a dot is an asteroid because it will shift its position against stars in the background as it moves in its orbit. Boffinry chiefs plan to put all the imagery online as soon as they get it, so that amateur enthusiasts can aid them in discovering any objects of interest: you can find full details here.

"If we discover the asteroids have the same composition as the Earth and moon, it will support [the 'Theia'] version of the giant impact theory," says Kaiser. "Also, the L4/L5 regions might be the home of future Earth-impacting asteroids." ®

Securing Web Applications Made Simple and Scalable

More from The Register

next story
World Solar Challenge contender claims new speed record
One charge sees Sunswift travel 500kms at over 100 km/h
SMELL YOU LATER, LOSERS – Dumbo tells rats, dogs... humans
Junk in the trunk? That's what people have
The Sun took a day off last week and made NO sunspots
Someone needs to get that lazy star cooking again before things get cold around here
Boffins discuss AI space program at hush-hush IARPA confab
IBM, MIT, plenty of others invited to fill Uncle Sam's spy toolchest, but where's Google?
Famous 'Dish' radio telescope to be emptied in budget crisis: CSIRO
Radio astronomy suffering to protect Square Kilometre Array
BEST BATTERY EVER: All lithium, all the time, plus a dash of carbon nano-stuff
We have found the Holy Grail (of batteries) - boffins
Bad back? Show some spine and stop popping paracetamol
Study finds common pain-killer doesn't reduce pain or shorten recovery
Forty-five years ago: FOOTPRINTS FOUND ON MOON
NASA won't be back any time soon, sadly
Jurassic squawk: Dinos were Earth's early FEATHERED friends
Boffins research: Ancient dinos may all have had 'potential' fluff
prev story

Whitepapers

Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
Seven Steps to Software Security
Seven practical steps you can begin to take today to secure your applications and prevent the damages a successful cyber-attack can cause.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.