Category Archives: Asteroids

NASA’s Asteroid Encounter

NASA’s Osiris-REx is basically “on approach” to asteroid Bennu, and so far everything seems to proceeding nicely.

NASA — NASA’s OSIRIS-REx spacecraft executed its first Asteroid Approach Maneuver (AAM-1) today putting it on course for its scheduled arrival at the asteroid Bennu in December. The spacecraft’s main engine thrusters fired in a braking maneuver designed to slow the spacecraft’s speed relative to Bennu from approximately 1,100 mph (491 m/sec) to 313 mph (140 m/sec). The mission team will continue to examine telemetry and tracking data as they become available and will have more information on the results of the maneuver over the next week.

During the next six weeks, the OSIRIS-REx spacecraft will continue executing the series of asteroid approach maneuvers designed to fly the spacecraft through a precise corridor during its final slow approach to Bennu. The last of these, AAM-4, scheduled for Nov. 12, will adjust the spacecraft’s trajectory to arrive at a position 12 miles (20 km) from Bennu on Dec. 3. After arrival, the spacecraft will initiate asteroid proximity operations by performing a series of fly-bys over Bennu’s poles and equator

Credits: University of Arizona

A Bit of Asteroid Itokawa

Along with the likes of the Cassini and Rosetta missions we have the history making Hayabusa Mission. The mission actually returned a sample from the asteroid Itokawa and the mission at least for me showcases the resilience of the JAXA mission team (see the section “Changes in mission plan” in the provided link.

The image above was released yesterday 01 Aug 2018 by ESA.

Here’s the caption included in the release:

ESA: Seen on a microscopic support, this sharp-edged grain of rock is an extraterrestrial object – a tiny sample from the Itokawa asteroid, retrieved by Japan’s Hayabusa mission and now being tested by ESA researchers.

Japan’s Hayabusa spacecraft was the world’s first mission to retrieve samples from the surface of an asteroid and return them to Earth. Beset by many problems, after a seven-year, six-billion-km odyssey Hayabusa returned around 1 500 precious asteroid grains to Earth.

Extremely precious, these Hayabusa grains have become the focus of scientific study around the world – and three of them are currently here, at ESA’s ESTEC technical centre in the Netherlands.

Researcher Fabrice Cipriani is leading research into their static charging properties, to understand the consequences for the surface environments of asteroids.

Hera Mission

What happens when we impact an asteroid, other than the obvious crater and debris, can we actually change its trajectory? The Hera mission is designed to find out by impacting “Didymoon” as the video explains. Didymoon is part of the Didymos system.

By the way if the name Didymos is familiar, you may be thinking of of the didymo we see here on Earth.

JAXA Sees Asteroid Ryugu Up Close

JAXA shows us the very unique shape of Asteroid Ryugu. The image was taken from JAXA’s Hayabusa2 using the ONC-T (Optical Navigation Camera). Image Credit: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, Aizu University, AIST

The range from spacecraft to asteroid was only 40 km / 25 miles on 24 June 2018.

The caption from JAXA (Project Manager, Yuichi Tsuda): The shape of Ryugu is now revealed. From a distance, Ryugu initially appeared round, then gradually turned into a square before becoming a beautiful shape similar to fluorite [known as the ‘firefly stone’ in Japanese]. Now, craters are visible, rocks are visible and the geographical features are seen to vary from place to place. This form of Ryugu is scientifically surprising and also poses a few engineering challenges.

First of all, the rotation axis of the asteroid is perpendicular to the orbit. This fact increases the degrees of freedom for landing and the rover decent operations. On the other hand, there is a peak in the vicinity of the equator and a number of large craters, which makes the selection of the landing points both interesting and difficult. Globally, the asteroid also has a shape like fluorite (or maybe an abacus bead?). This means we expect the direction of the gravitational force on the wide areas of the asteroid surface to not point directly down. We therefore need a detailed investigation of these properties to formulate our future operation plans.

The Project Team is fascinated by the appearance of Ryugu and morale is rising at the prospect of this challenge. Together with all of you, we have become the first eyewitnesses to see asteroid Ryugu. I feel this amazing honor as we proceed with the mission operations.

Asteroid 2018 LA Strikes Earth

Asteroid 2018 LA was discovered early on 02 June 2018 and was determined to be on a collision course with Earth. This rock was only a couple of meters across so it was small, still I would have hoped to hear something about it on the news – there is a reason for that as you will see. The really great part about all of this is this tiny asteroid was spotted at all. Credits: NASA/JPL-Caltech/CSS-Univ. of Arizona

Anyway. . .

The story from NASA is below but there are reports of meteors falling to Earth over the weekend at about the same time. One in China where fragments of meteorites that fell in southwest China’s on June 1 have been found in a village of the province’s Menghai County, Yunnan Province. Reports had two fragments coming through roofs and one being found in a corn field.

Another is from farmer Barend Swanepoel in South Africa and not only did he witness the incoming meteor he captured a video and posted in on Face Book. Here’s the YouTube version:

NASA: A boulder-sized asteroid designated 2018 LA was discovered Saturday morning, June 2, and was determined to be on a collision course with Earth, with impact just hours away. Because it was very faint, the asteroid was estimated to be only about 6 feet (2 meters) across, which is small enough that it was expected to safely disintegrate in Earth’s atmosphere. Saturday’s asteroid was first discovered by the NASA-funded Catalina Sky Survey, located near Tucson and operated by the University of Arizona.

Although there was not enough tracking data to make precise predictions ahead of time, a swath of possible locations was calculated stretching from Southern Africa, across the Indian Ocean, and onto New Guinea. Reports of a bright fireball above Botswana, Africa, early Saturday evening match up with the predicted trajectory for the asteroid. The asteroid entered Earth’s atmosphere at the high speed of 10 miles per second (38,000 mph, or 17 kilometers per second) at about 16:44 UTC (9:44 a.m. PDT, 12:44 p.m. EDT, 6:44 p.m. local Botswana time) and disintegrated several miles above the surface, creating a bright fireball that lit up the evening sky. The event was witnessed by a number of observers and was caught on webcam video.

When it was first detected, the asteroid was nearly as far away as the Moon’s orbit, although that was not initially known. The asteroid appeared as a streak in the series of time-exposure images taken by the Catalina telescope . As is the case for all asteroid-hunting projects, the data were quickly sent to the Minor Planet Center in Cambridge, Massachusetts, which calculated a preliminary trajectory indicating the possibility of an Earth impact. The data were in turn sent to the Center for Near-Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory in Pasadena, California, where the automated Scout system also found a high probability that the asteroid was on an impact trajectory. Automated alerts were sent out to the community of asteroid observers to obtain further observations, and to the Planetary Defense Coordination Office at NASA Headquarters in Washington. However, since the asteroid was determined to be so small and therefore harmless, no further impact alerts were issued by NASA.

“This was a much smaller object than we are tasked to detect and warn about,” said Lindley Johnson, Planetary Defense Officer at NASA Headquarters. “However, this real-world event allows us to exercise our capabilities and gives some confidence our impact prediction models are adequate to respond to the potential impact of a larger object.”

Four Years of NEOWISE

Impressive four years of NEOWISE operation:

Asteroids detected or observed 29,000
Near Earth Objects: 788

About the video (NASA): The orbits of Mercury, Venus and Mars are shown in blue. Earth’s orbit is in teal.

Green dots represent near-Earth objects. Gray dots represent all other asteroids which are mainly in the main asteroid belt between Mars and Jupiter. Yellow squares represent comets.

Upcoming this week:

22 April 2018: Earth Day

25 April 2018 (Wednesday): ESA’s Sentinel 3B Satellite launches atop a Russian Rokot. I believe launch time is 17:57 UTC.

Also Mercury is heading towards maximum Western elongation (29 April @ 27 degrees), we might get a look at it just before sun up in the Eastern sky. If you do go looking for Mercury as always be very-very careful. The Sun isn’t far away and you could be badly injured if you look at the sun, especially if you are using any magnifying devices.

What About Arecibo?

Just the other day I was wondering what was going on at Arecibo. You may recall Arecibo and the rest of Puerto Rico was pretty much turned into a disaster zone by Hurricane Maria. The rebuilding progress for Puerto Rico has been slow.

Arecibo on the other hand is apparently up and running just fine and it even got a look at asteroid Phaethon. Very pleased to hear of the return of this great observatory!

Original caption from NASA:
These radar images of near-Earth asteroid 3200 Phaethon were generated by astronomers at the National Science Foundation’s Arecibo Observatory on Dec. 17, 2017. Observations of Phaethon were conducted at Arecibo from Dec.15 through 19, 2017. At time of closest approach on Dec. 16 at 3 p.m. PST (6 p.m. EST, 11 p.m. UTC) the asteroid was about 6.4 million miles (10.3 million kilometers) away, or about 27 times the distance from Earth to the moon. The encounter is the closest the object will come to Earth until 2093.

The Arecibo Planetary Radar Program is funded by NASA’s Near-Earth Object Observations Program through a grant to Universities Space Research Association (USRA), from the Near-Earth Object Observations program. The Arecibo Observatory is a facility of the National Science Foundation operated under cooperative agreement by SRI International, USRA, and Universidad Metropolitana.

Oumuamua

Very cool. An interstellar asteroid called Oumuamua.

We are getting some great information starting with two videos about Oumuamua. The first is from ESO:

And the second from NASA:

Finally a press release from NASA:

Now, new data reveal the interstellar interloper to be a rocky, cigar-shaped object with a somewhat reddish hue. The asteroid, named ‘Oumuamua by its discoverers, is up to one-quarter mile (400 meters) long and highly-elongated—perhaps 10 times as long as it is wide. That aspect ratio is greater than that of any asteroid or comet observed in our solar system to date. While its elongated shape is quite surprising, and unlike asteroids seen in our solar system, it may provide new clues into how other solar systems formed.

The observations and analyses were funded in part by NASA and appear in the Nov. 20 issue of the journal Nature. They suggest this unusual object had been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with our star system.

“For decades we’ve theorized that such interstellar objects are out there, and now – for the first time – we have direct evidence they exist,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate in Washington. “This history-making discovery is opening a new window to study formation of solar systems beyond our own.”

Immediately after its discovery, telescopes around the world, including ESO’s Very Large Telescope in Chile and other observatories around the world were called into action to measure the object’s orbit, brightness and color. Urgency for viewing from ground-based telescopes was vital to get the best data.

Combining the images from the FORS instrument on the ESO telescope using four different filters with those of other large telescopes, a team of astronomers led by Karen Meech of the Institute for Astronomy in Hawaii found that ‘Oumuamua varies in brightness by a factor of ten as it spins on its axis every 7.3 hours. No known asteroid or comet from our solar system varies so widely in brightness, with such a large ratio between length and width. The most elongated objects we have seen to date are no more than three times longer than they are wide.

“This unusually big variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape,” said Meech. We also found that it had a reddish color, similar to objects in the outer solar system, and confirmed that it is completely inert, without the faintest hint of dust around it.”

These properties suggest that ‘Oumuamua is dense, comprised of rock and possibly metals, has no water or ice, and that its surface was reddened due to the effects of irradiation from cosmic rays over hundreds of millions of years.

A few large ground-based telescopes continue to track the asteroid, though it’s rapidly fading as it recedes from our planet. Two of NASA’s space telescopes (Hubble and Spitzer) are tracking the object the week of Nov. 20. As of Nov. 20, ‘Oumuamua is travelling about 85,700 miles per hour (38.3 kilometers per second) relative to the Sun. Its location is approximately 124 million miles (200 million kilometers) from Earth — the distance between Mars and Jupiter – though its outbound path is about 20 degrees above the plane of planets that orbit the Sun. The object passed Mars’s orbit around Nov. 1 and will pass Jupiter’s orbit in May of 2018. It will travel beyond Saturn’s orbit in January 2019; as it leaves our solar system, ‘Oumuamua will head for the constellation Pegasus.

Observations from large ground-based telescopes will continue until the object becomes too faint to be detected, sometime after mid-December. NASA’s Center for Near-Earth Object Studies (CNEOS) continues to take all available tracking measurements to refine the trajectory of 1I/2017 U1 as it exits our solar system.

This remarkable object was discovered Oct. 19 by the University of Hawaii’s Pan-STARRS1 telescope, funded by NASA’s Near-Earth Object Observations(NEOO) Program, which finds and tracks asteroids and comets in Earth’s neighborhood. NASA Planetary Defense Officer Lindley Johnson said, “We are fortunate that our sky survey telescope was looking in the right place at the right time to capture this historic moment. This serendipitous discovery is bonus science enabled by NASA’s efforts to find, track and characterize near-Earth objects that could potentially pose a threat to our planet.”

Preliminary orbital calculations suggest that the object came from the approximate direction of the bright star Vega, in the northern constellation of Lyra. However, it took so long for the interstellar object to make the journey – even at the speed of about 59,000 miles per hour (26.4 kilometers per second) — that Vega was not near that position when the asteroid was there about 300,000 years ago.

While originally classified as a comet, observations from ESO and elsewhere revealed no signs of cometary activity after it slingshotted past the Sun on Sept. 9 at a blistering speed of 196,000 miles per hour (87.3 kilometers per second).

The object has since been reclassified as interstellar asteroid 1I/2017 U1 by the International Astronomical Union (IAU), which is responsible for granting official names to bodies in the solar system and beyond. In addition to the technical name, the Pan-STARRS team dubbed it ‘Oumuamua (pronounced oh MOO-uh MOO-uh), which is Hawaiian for “a messenger from afar arriving first.”

Astronomers estimate that an interstellar asteroid similar to ‘Oumuamua passes through the inner solar system about once per year, but they are faint and hard to spot and have been missed until now. It is only recently that survey telescopes, such as Pan-STARRS, are powerful enough to have a chance to discover them.

“What a fascinating discovery this is!” said Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory, Pasadena, California. “It’s a strange visitor from a faraway star system, shaped like nothing we’ve ever seen in our own solar system neighborhood.”

Videos: ESO / NASA

Press release: NASA