Within Earth’s orbit, there are an estimated eighteen-thousands Near-Earth Asteroids (NEAs), objects whose orbit periodically takes them close to Earth. Because these asteroids sometimes make close flybys to Earth – and have collided with Earth in the past – they are naturally seen as a potential hazard. For this reason, scientists are dedicated to tracking NEAs, as well as studying their origin and evolution.
In 2003, the Japanese Aerospace Exploration Agency (JAXA) launched the Hayabusa probe. Its mission was to rendezvous with asteroid 25143 Itokawa in 2005. Once there, it studied a number of things about Itokawa, including its shape, topography, composition, colour, spin, density, and history. But the most exciting part of its mission was to collect samples from the asteroid and return them to Earth.
The mission suffered some complications, including the failure of Minerva, Hayabusa’s detachable mini-lander. But Hayabusa did land on the asteroid, and it did collect some samples; tiny grains of material from the surface of Itokawa. This was the first time a mission had landed somewhere and returned samples, other than missions to the Moon.
Once the collected grains made it back to Earth in 2010, and were confirmed to be from the asteroid, scientists got excited. These grains would be key to helping understand the early Solar System when the planetary bodies were formed. And they have revealed a sometimes violent history going back 4.5 billion years.
The grains themselves are truly microscopic, at just over 10 micrometers in size. The marks and surface patterns on them are measured in nanometers. Initially, all the marks on the surfaces of the particles were thought to be of one type. But the team behind the study used electron microscopes and X-Ray Microtomography to reveal four different types of patterns on their surfaces.
One 4.5 billion year old pattern shows crystallization from intense heat. At this time period, Itokawa was part of a larger asteroid. The second pattern indicates a collision with a meteor about 1.3 billion years ago. Another pattern was formed by exposure to the solar wind between 1 million and 1,000 years ago. A fourth pattern detected by scientists shows that the particles have been rubbing against each other.
The team has concluded that Itokawa didn’t always exist in its current shape and form. When it was formed over 4 billion years ago, it was about 40 times bigger than it is now. That parent body was destroyed, and the researchers think that Itokawa re-formed from fragments of the parent body.
If there is still any lingering doubt about the violent nature of the Solar System’s history, the grains from Itokawa help dispel it. Collision, fragmentation, bombardments, and of course solar wind, seem to be the norm in our Solar System’s history.
The return of these samples was a bit of a happy accident. The sample collection mechanism on Hayabusa suffered a failure, and the returned dust grains were actually kicked up by the landing of the probe, and some ended up in the sample capsule.
For their part, JAXA has already launched Hayabusa’s successor, Hayabusa 2. It was launched in December 2014, and is headed for asteroid 162173 Ryugu. It should reach its destination in July 2018, and spend a year and a half there. Hayabusa 2 is also designed to collect asteroid samples and return them to Earth, this time using an explosive device to dig into the asteroid’s surface for a sample. Hayabusa 2 should return to Earth in December 2020.
Hayabusa suffered several failures, including the failure of its mini-lander, problems with sample collection, and it even suffered damaged to its solar panels caused by a solar flare, which reduced its power and delayed its arrival at Itokawa. Yet it still ended up being a success in the end.
If Hayabusa 2 can avoid some of these problems, who knows what we may learn from more intentional samples. Sample missions are tricky and complex. If Hayabusa can return samples, it would be only the fourth body to have samples successfully returned to Earth, including the Moon, asteroid Itokawa, and comet Wild 2.
Correction, 11:33 a.m. EST: The University of Central Florida’s Phil Metzger points out that the image composition leaves out Eros, which NEAR Shoemaker landed on in 2001. This article has been corrected to reflect that and to clarify that the surfaces pictured were from “soft” landings.
And now there are eight. With Philae’s incredible landing on a comet earlier this week, humans have now done soft landings on eight solar system bodies. And that’s just in the first 57 years of space exploration. How far do you think we’ll reach in the next six decades? Let us know in the comments … if you dare.
More seriously, this amazing composition comes courtesy of two people who generously compiled images from the following missions: Rosetta/Philae (European Space Agency), Hayabusa (Japan Aerospace Exploration Agency), Apollo 17 (NASA), Venera 14 (Soviet Union), the Spirit rover (NASA) and Cassini-Huygens (NASA/ESA). Omitted is NEAR Shoemaker, which landed on Eros in 2001.
Before Philae touched down on Comet 67P/Churyumov–Gerasimenko Wednesday, the NASA Jet Propulsion Laboratory’s Mike Malaska created a cool infographic of nearly every place we’ve lived or visited before then. This week, Michiel Straathof updated the infographic to include 67P (and generously gave us permission to use it.)
And remember that these are just the SURFACES of solar system bodies that we have visited. If you include all of the places that we have flown by or taken pictures from of a distance in space, the count numbers in the dozens — especially when considering prolific imagers such as Voyager 1 and Voyager 2, which flew by multiple planets and moons.
To check out a small sampling of pictures, visit this NASA website that shows some of the best shots we’ve taken in space.
From directly inferring the inside of an asteroid for the first time, astronomers have discovered these space rocks can have strange variations in density. The observations of Itokawa — which you may remember from the Japanese Hayabusa mission that landed on the asteroid in 2005 — not only teach us more about how asteroids came to be, but could help protect Earth against stray space rocks in the future, the researchers said.
“This is the first time we have ever been able to to determine what it is like inside an asteroid,” stated Stephen Lowry, a University of Kent scientist who led the research. “We can see that Itokawa has a highly varied structure; this finding is a significant step forward in our understanding of rocky bodies in the solar system.”
It’s not clear why Itokawa has such different densities at opposite sides of its peanut shape; perhaps it was two asteroids that rubbed up against each other and merged. At just shy of six American football fields long, the space rock has density varying from 1.75 to 2.85 grams per cubic centimetre. This precise measurement came courtesy of the European Southern Observatory’s New Technology Telescope in Chile.
The telescope calculated the speed and speed changes of Itokawa’s spin and combined that information with data on how sunlight can affect the spin rate. Asteroids are generally tiny and irregularly shaped sorts of bodies, which means the effect of heat on the body is not evenly distributed. That small difference makes the asteroid’s spin rate change.
This heat effect (more properly called the Yarkovsky-O’Keefe-Radzievskii-Paddack effect) is slowly making Itokawa’s spin rate go faster, at a rate of 0.045 seconds every Earth year. This change, previously unexpected by scientists, is only possible if the peanut bulges have different densities, the scientists said.
“Finding that asteroids don’t have homogeneous interiors has far-reaching implications, particularly for models of binary asteroid formation,” added Lowry. “It could also help with work on reducing the danger of asteroid collisions with Earth, or with plans for future trips to these rocky bodies.”
More details on the research will be available in the journal Astronomy and Astrophysics.
Source: European Southern Observatory
No visible material from asteroid Itokawa was found inside the second compartment of a canister returned to Earth by the Hayabusa spacecraft. However, JAXA also announced that more micron-sized grains have been found in the first compartment, opened earlier this year. Reportedly, the first compartment has about 1,500 tiny particles, however some might be aluminum particles from the container itself. But about 20 grains were rocky or mineral-based. However, according to the Daily Yomiuri Online, no visible material was inside the second chamber, although further investigations of the second compartment will be done with a special microscope.
Hayabusa attempted to land on Itokawa twice. The cylindrical canister was divided into two chambers, and the second chamber was to contain material collected during the spacecraft’s first landing.
JAXA officials expect the second compartment to contain more microscopic particles from Itokawa since the first landing was longer than the second.
As far as the particles from the first chamber, several have been observed with an electron microscope, and according to UmannedSpaceflight.com, the “rocky” ones are 30 microns in size, with several larger ones are about 100 microns.
JAXA hopes to provide more insight on the nature of the grains by the end of the year.
The Japan Aerospace Exploration Agency (JAXA) has confirmed that the tiny particles inside the Hayabusa spacecraft’s sample return container are in fact from the asteroid Itokawa. Scientists examined the particles to determine if the probe successfully captured and brought back anything from the asteroid, and in a press release said “about 1,500 grains were identified as rocky particles, and most were determined to be of extraterrestrial origin, and definitely from Asteroid Itokawa.”
These are the first samples from an asteroid ever returned to Earth;
the only other extraterrestrial samples brought back to Earth came from the Apollo missions to the Moon. See correction, below.
Previously, JAXA said that although particles were inside the container, it wasn’t clear if they were from the asteroid or if they could be of terrestrial origin (dust from Earth that could have been inside the container).
The particles samples were collected from the chamber by a specially shaped Teflon spatula and examined with a scanning electron microscope. There were two chambers inside the container, and from the press release (in Japanese) it appears all the particles were found in one chamber, Chamber A.
Most of the particles are extremely small, about 10 microns in size and require special handling and equipment. Unfortunately they aren’t the “peanut-sized” chunks of rock that the mission originally hoped to capture. This will make analyzing the particles difficult, but not impossible.
During the seven-year round trip journey, Hayabusa arrived at Itokawa in November, 2005. The mechanism that was intended to capture the samples apparently failed, but scientists were hopeful that at least some dust had made its way into the return canister. After a circuitous and troubled-filled return trip home, the sample return capsule was ejected and landed in Australia in June of this year.
Here are the other successful sample return missions:
Apollo Moon missions (1969-1972)
Soviet Union’s Luna 16 (1970) returned 101 grams of lunar soil
Luna 20 (1974) returned 30 grams
Luna 24 (1976) returned 170.1 grams.
The Orbital Debris Collection (ODC) experiment, deployed on the Mir space station for 18 months during 1996–1997, used aerogel to capture interplanetary dust particles in orbit.
Genesis (2001-2004) captured and returned molecules collected from the solar wind. It crashed in the Utah desert, but samples were able to be retreived.
Stardust (1999-2006) collected particles from the tail of a comet, as well as a few interstellar dust grains.
At a press conference yesterday, officials from the Japan Aerospace Exploration Agency (JAXA) announced that they had “scraped up” a hundred or so particles of dust, perhaps grains of dust from the asteroid, Itokawa, inside the sample return capsule of the Hayabusa spacecraft. This is great news, as previous reports from JAXA indicated they weren’t sure if there were any particles at all inside the container. Originally, the mission had hoped to bring back “peanut-sized” asteroid samples, but the device that was supposed to fire pellets at the asteroid may not have worked, and for a time, scientists were even unsure if the spacecraft had even touched down on the asteroid.
During the seven-year round trip journey, Hayabusa arrived at Itokawa in November, 2005. After a circuitous and troubled-filled return trip home, the sample return capsule was ejected and landed in Australia in June of this year.
The 100 or so grains reported yesterday are extremely tiny, and the micron-sized particles were scraped off the sides of container and are now being examined with an electron microscope. They don’t appear to be metallic, so are not fragments from the container, but they don’t have absolute proof yet that the particles are from the asteroid.
Soon, the grains will be examined using particle accelerator/synchrotron. Additionally, some reports indicated there is another yet unopened compartment that will be examined soon.
A little surfing of the net (in all languages) reveals there are tons of news articles out there reporting this. The only problem is that some of these news reports called the potential asteroid particles “extraterrestrial,” which then became translated as “extraterrestrial life” in the next article in another language. Ah, the wonders of the internet!
We’ll keep you posted!
The sample return canister from the Hayabusa spacecraft has been opened, and does contain a small amount of dust particles, according to the JAXA website. This is very encouraging news! However, it is not yet known if the dust is from the asteroid Itokawa, where Hayabusa briefly touched down, or if it could be from Earth — left in the container from before launch, or it possibly could have made its way in there during the landing/post landing handling. “Material on the planet or asteroid or particulate matter is at this stage is unknown, we will consider in detail,” is the Google translate version of the JAXA press release. According to Emily Lakdawalla at the Planetary Society, the dust grains are extremely small, about 0.01-millimeter in size, and there are about a dozen of them inside the container. This image was taken on June 28, 2010, and below is a magnified view of one of the particles.
This magnified view was taken on June 29, and shows a magnified view of one very small particle being picked up by a quartz manipulator, which appears as a stripe on the image.
It likely will take several weeks to confirm whether the particles are from the asteroid, but if so, would be the first-ever asteroid sample return.
Below is an image of Earth that Hayabusa took as it approached the home planet.