Paris (AFP) – The Moon, our planet’s constant companion for some 4.5 billion years, may have been forged by a rash of smaller bodies smashing into an embryonic Earth, researchers said Monday.
Such a bombardment birth would explain a major inconsistency in the prevailing hypothesis that the Moon splintered off in a single, giant impact between Earth and a Mars-sized celestial body.
“The multiple impact scenario is a more ‘natural’ way of explaining the formation of the Moon.”
In such a scenario, scientists expect that about a fifth of the Moon’s material would have come from Earth and the rest from the impacting body.
Yet, the makeup of the Earth and the Moon are near identical — an improbability that has long perplexed backers of the single-impact hypothesis.
“In the early stages of the Solar System, impacts were very abundant, therefore it is more natural that several common impactors formed the Moon rather than one special one.”
“The multiple impact scenario is a more ‘natural’ way of explaining the formation of the Moon,” said Raluca Rufu of the Weizmann Institute of Science in Rehovot, who co-authored the new study published in the journal Nature Geoscience.
Such multiple hits would have excavated more Earth material than a single one, which means the moonlets would more closely resemble our planet’s composition, said the study authors. Read the rest of this entry »
Loren Grush reports: NASA’s Juno spacecraft has successfully entered Jupiter’s orbit, bringing it closer to the planet than any probe has come so far. The vehicle reached the gas giant’s north pole this evening, and NASA received confirmation that the vehicle had turned on its main engine at 11:18PM ET. The engine burned for 35 minutes, helping to slow the spacecraft down enough so that it was captured by Jupiter’s gravitational pull. NASA confirmed that the burn was successful at around 11:53PM ET and that Juno was in its intended 53-day orbit.
— NASA (@NASA) July 5, 2016
The orbit insertion was a bit of a nail biter for NASA, as the spacecraft had to travel through regions of powerful radiation and rings of debris surrounding Jupiter. As an added precaution, the probe’s instruments were turned off for the maneuver so that nothing would interfere with the engine burn. But everything seemed to work flawlessly, and NASA received confirmation of the burn’s success almost exactly as expected. The timing only differed by 1 second from pre-burn predictions.
That confirmation came 48 minutes after the event actually occurred, though. That’s because it currently takes 48 minutes to send a signal from Jupiter to Earth. Juno started its burn at around 10:30PM ET and finished at 11:05PM ET, but NASA didn’t confirm all of this until just before midnight. If something had gone wrong and stopped the burn too early, the space agency wouldn’t have been in a position to fix the problem. Read the rest of this entry »
Jennifer Ouellette reports: NASA’s Juno spacecraft has been spinning through space on its way to Jupiter for five years and 445 million miles, and now it’s less than 10 hours away from entering the gas giant’s orbit—the equivalent of a single rotation of Jupiter. If all goes well, scientists will finally be able to learn what lies beneath Jupiter’s turbulent atmosphere, examine its impressive magnetosphere, and possibly determine the composition of its core.
“If Juno gets hit even by a small piece of dust, it can do a great bit of damage,” he said. “We believe probability is incredibly low that Juno will hit dust or debris, but it’s not zero. Even a 10 micron particle could do some damage moving at the speed we’re moving.”
— Juno project manager Scott Bolton
But first, it’s going to have to execute a tricky 35-minute engine burn under the harshest conditions any NASA spacecraft has yet faced. And that has Juno mission scientists on edge today. They’ve modeled every scenario they can think of, and planned for every contingency. But as Juno project manager Scott Bolton said in this morning’s briefing at the Jet Propulsion Laboratory in Pasadena, “This is the highest risk phase.”
“We’ve done everything humanly possible to make this mission a success, but it’s still a cliffhanger,” said Jim Green, director of planetary science at NASA headquarters in Washington, DC.
Thus far, the mission has gone off without a hitch, but plenty could still go wrong. For instance, what if the main engine doesn’t fire on cue to start the burn, so far from the sun? “We’ve fired the main engine twice successfully and the third time should be a charm,” said Rick Nybakken, Juno project manager. “But this is the first time we’ve ever fired the main engine at Jupiter. It’s make or break for us.”
Then there’s the intense radiation from Jupiter’s enormous magnetosphere. According to Heidi Becker, lead investigator for Juno’s radiation monitoring, this translates into millions of high energy electrons moving near the speed of light. “They will go right though the spacecraft,” she said. “It’s the equivalent of 100 million x-rays in less than a year for a human being if we had no protection.”
Juno’s polar orbit will avoid the worst of the radiation belts at the planet’s equator, but other high-intensity regions are unavoidable. Read the rest of this entry »
Bruce Dormancy writes: Holiday shopping for items from the Moon, Mars and the wilds of outer space is still possible for those open to meteoritic stocking stuffers. Such truly ancient pieces of space rock — think older than Earth itself — are increasingly sought after by hundreds of high-end collectors looking for natural pieces of sculpture.
Although a plethora of commercial startups are pining for metal riches from asteroids in the Main Asteroid Belt and beyond, meteorite collectors here on terra firma now routinely buy and sell these off-world treasures at auction.
Christie’s South Kensington Auction House in London is planning their first catalog sale of meteorites next April. Prices typically range from around $500 to over $100,000, depending on the size, type of meteorites, condition and provenance, James Hyslop, the Head of Science & Books at Christie’s South Kensington, told me.
However, some meteorites can sell for much higher.
The Chinese Academy of Sciences in Beijing paid a cool $1 million for two small Mars meteorites. Indeed, Hyslop says lunar and Martian meteorites are the most sought after, since they are also the most rare; representing less than one percent of the estimated 62,000 catalogued meteorites. The rest all originate from asteroidal or cometary bodies in deep space.
Darryl Pitt, Curator of the Macovich Collection of Meteorites in New York — one of the world’s largest private collections, told me that any given meteorite’s sales value is also influenced by other factors. They include whether the piece is whole or fractured; its locality at the time of discovery; its esthetics; color; crystalline structure and translucency.
And often, the more bizarre their shapes, the better collectors like it. Hyslop notes that meteorites with naturally-occurring holes are much rarer and more highly-prized.
Alan Rubin, a UCLA research geochemist, told me that such bizarre shapes result from both fragmentation while traveling through Earth’s atmosphere and often years of terrestrial weathering after hitting the ground.
But the hot quick trip through our atmosphere is nothing to compared to their circuitous orbital routes to Earth itself.
For meteorites that originated on the Moon or Mars, their journeys here can take up to millions of years. Most lunar meteorites either reach the Earth in a few days or achieve quasi-geocentric orbits that bring them to Earth in less than a million years,” said Rubin.
Mars meteorites typically take much longer.
Rubin says we know this as a result of cosmic ray dating on the meteorites themselves.
He says that when objects in interplanetary space are less than a few meters in size, they are penetrated by cosmic rays which transmute some elements into measurable radioactive isotopes. Read the rest of this entry »
This perspective view of Pluto, based on the latest high-resolution images from NASA’s New Horizons spacecraft, shows what you would see if you were approximately 1,100 miles (1,800 kilometers) above Pluto’s equatorial area, looking northeast over the dark, cratered, informally named Cthulhu Regio toward the bright, smooth, expanse of icy plains informally called Sputnik Planum. The entire expanse of terrain seen in this image is 1,100 miles (1,800 kilometers) across. The images were taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers).
NASA will detail a major science finding from the agency’s ongoing exploration of Mars during a news briefing at 11:30 a.m. EDT on Monday, Sept. 28 at the James Webb Auditorium at NASA Headquarters in Washington. The event will be broadcast live on NASA Television and the agency’s website.
News conference participants will be:
· Jim Green, director of planetary science at NASA Headquarters
· Michael Meyer, lead scientist for the Mars Exploration Program at NASA Headquarters
· Lujendra Ojha of the Georgia Institute of Technology in Atlanta
A brief question-and-answer session will take place during the event with reporters on site and by phone. Members of the public also can ask questions during the briefing using #AskNASA.
To participate in the briefing by phone, reporters must email their name, media affiliation and telephone number to Steve Cole at firstname.lastname@example.org by 9 a.m. EDT on Monday. Read the rest of this entry »
This is how fast the space probe is.
- Historic results from the New Horizons mission are due to be revealed in a briefing at 20:00 BST
- They will include close-up photos of Pluto and its biggest moon Charon
- Nasa’s spacecraft soared past Pluto on Tuesday and first “phoned home” at 01:52 BST Wednesday
- The image taken just before the flyby already shows the dwarf planet in unprecedented detail
— jonkeegan (@jonkeegan) July 15, 2015
Have you ever wanted to travel to Mars? What if it meant living there for the rest of your life? That’s the opportunity Mars One is offering to volunteers who will help establish human settlement on the Red Planet. The downside is that the technology for a return trip hasn’t been developed yet. That doesn’t seem to be deterring the masses of applicants– Mars One says that more than 200,000 people have applied. In order to narrow down the applicants and help fund the project, the company is considering sponsoring a reality show where viewers will help select the Mars pioneers.