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10/02/2022 – Ephemeris Extra – NASA goes on the offensive

October 2, 2022 Leave a comment
Didymus and Dimorphos from DART

DART images of both Didymos, the big one, and Dimorphos, on approach. Credit NASA / JHAPL

This is a slightly revised version of my article in the Stellar Sentinel, the newsletter of the Grand Traverse Astronomical Society. Educators may receive a free PDF copy of this monthly publication via email, which covers astronomical topics and events visible from Northwest Lower Michigan. Send your request, stating your affiliation, to info@gtastro.org.

The score is: Asteroids-billions, NASA-1. It’s a bit unfair, since asteroids have been hitting the Earth for 4.567 billion years or so, and NASA has been around for 64 years before DART spacecraft collided with the asteroid Dimorphos. Hey, this was their first attempt at a small asteroid. As far as the 21st century destructive asteroid score is 1 to NASA’s 1, as far as I know.
That strike was in Chelyabinsk, Russia. That was February 15, 2013. We were all waiting on another asteroid making a close pass of the Earth, when the Chelyabinsk meteoroid exploded 14 miles above the city. Over a thousand people were injured by the blast wave. They saw the bright flash and rushed to the windows to see what it was. Then the blast wave hit, shattering the windows, causing glass cuts for over a thousand people. One building’s wall collapsed, and a fragment fell into a lake outside of town.
NASA’s record in attempting to hit a planetary object dates back to the early 1960s and the nine Pioneer missions to crash a probe on the Moon, sending back pictures all the way down. Back in the early 60s, just hitting a 2,100-mile (3380 kilometer) wide object a quarter of a million miles away was a dicey prospect. It’s one thing to miss the Moon on one side or the other, but to not have enough oomph to even make it all the way is downright embarrassing. NASA did much better by the end of the decade with the Apollo manned landings and bombarding the Moon with used space vehicles for seismic studies of its interior.
NASA actually collided a spacecraft into a comet. That was July 4, 2005, when the impactor part of the Deep Impact spacecraft hit Comet Tempel 1’s nucleus, attempting to study part of its subsurface. The non-impactor part was later renamed EPOXI and went on to fly by the dog-bone shaped Hartley 2 comet nucleus. Another reused comet explorer spacecraft Stardust after collecting cometary dust from Comet Wild 2 (pronounced Vilt 2), and possible interstellar dust penetrating the solar system, and after dropping the sample re-entry capsule back on Earth it ended in solar orbit. Later it was repurposed as the Stardust-NexT mission and flew by Tempel 1 six years later to study the crater the Deep Impact Impactor made in the comet.
To study the effect of a collision of a spacecraft from the Earth despite the fact that Dimorphos cannot be seen is a trick. However, the pair is an eclipsing binary from our point of view, so the brightness of the unresolved pair changes as they eclipse each other.
Before the collision, Dimorphos had an 11.9 hour orbit of Didymos. Dimorphos is a fifth the size of Didymos orbiting it at three times the primary’s radius. If the orbit is near circular, Dimorphos’ orbital velocity is only 0.39 mph (0.63 kph). It should be relatively easy to see a tiny change in Dimorphos’ orbital period.

Last frame Dimorphos fit in from DART

Last frame Dimorphos fit in from DART. Credit NASA / JHAPL.

Two images from the LiciaCube satellite

Two images from the LiciaCube satellite launched from the DART spacecraft 15 days before the impact, and trailing it to record the collision with its wide and narrow angle imagers. Dimorphos does appear to be a rubble pile asteroid from its appearance and the amount of ejecta caused by the impact. The ejecta adds to the effect of the spacecraft’s kinetic energy by pushing away from the asteroid by Newton’s third law of motion. Credit: Italian Space Agency.

Dimorphos ejecta from Atlas

A frame from a time-lapse video taken from the ATLAS Project’s South African observatory of the unresolved Didymos – Dimorphos pair and the expanding ejecta cloud. The asteroid pair developed a dust tail like a comet for a while.
ATLAS is an acronym for a rather apocalyptic title “Asteroid Terrestrial-impact Last Alert System”. Developed by the University of Hawai’i and funded by NASA. It has two telescopes in Hawai’i, one in Chile, and one in South Africa. Credit: NASA/UH.

Days later, Dimorphos was exhibiting a thin dust tail, like a comet.

Now we wait on Earth’s observatories to observe of the period of Dimorphos’ orbit. It should decrease the orbital time.

02/17/2022 – Ephemeris – Mission to a metallic asteroid

February 17, 2022 Comments off

This is Ephemeris for Thursday, February 17th. Today the Sun will be up for 10 hours and 34 minutes, setting at 6:14, and it will rise tomorrow at 7:38. The Moon, 1 day past full, will rise at 7:21 this evening.

In August this year, one of the three scheduled Falcon-Heavy rocket launches this year will send the Psyche spacecraft on a four-year journey to its namesake asteroid, 16 Psyche. It is an unusual asteroid, thought to be 30 to 60 percent iron-nickel in composition. The spacecraft will swing by Mars for a gravitational boost. After the chemical powered boost into solar orbit, the spacecraft will open its huge solar panels in the shape of two crosses to feed its power hungry electric thrusters to complete the journey and to orbit 16 Psyche. The thrusters are Hall Effect thrusters, the first used in space, that use magnetic fields instead of electric fields to eject xenon gas ions to provide thrust. It is expected to arrive at 16 Psyche in 2026.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

Artist's visualization of the spacecraft Psyche orbiting asteroid 16 Psyche

Artist’s visualization of the spacecraft Psyche orbiting asteroid 16 Psyche. This imagining seems to assume the asteroid is nearly 100% metallic. Credit: NASA.

02/14/2022 – Ephemeris – A celestial Valentine’s Day encounter

February 14, 2022 Comments off

This is Bob Moler with Ephemeris for St Valentine’s Day, Monday, February 14th. Today the Sun will be up for 10 hours and 25 minutes, setting at 6:10, and it will rise tomorrow at 7:43. The Moon, 2 days before full, will set at 7:40 tomorrow morning.

Twenty-two years ago to the day, the NEAR-Shoemaker* spacecraft entered into orbit of the near Earth asteroid 433 Eros. It wasn’t originally planned to enter orbit of the asteroid named after the Greek god of love on Valentine’s Day, 2000. It arose after an aborted course correction a year earlier. After solving the problem, a new course was plotted and NEAR-Shoemaker was gently inserted into orbit of this 21 mile long asteroid shaped like a bent bread stick with a bite taken out of the center of it. The spacecraft spent almost a year orbiting Eros at various altitudes. The spacecraft ended its mission gently crashing into the middle of the asteroid, where it stayed alive for two weeks before succumbing to the cold.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

*The name Shoemaker was added to the NEAR spacecraft name after it was launched. NEAR stands for Near Earth Asteroid Rendezvous.  It was named for Eugene Shoemaker, a geologist who proved that the Barringer Crater in Arizona was an impact crater rather than a volcanic crater, thus proving, before the Apollo 11 landing on the Moon, that the Moon’s craters were mostly impact craters produced by small asteroids like Eros. Shoemaker and his wife Carolyn, the astronomer in the family, along with David Levy discovered the Comet Shoemaker-Levy 9. The comet had broken into more than 22 pieces and crashed into Jupiter over a week in July 1994, making blemishes in the Jovian clouds that lasted many months.

Addendum

Six views of Eros as it tumbled

“These color images of Eros were taken by the NEAR probe on February 12, 2000, at a distance of 1,800 kilometers, during the final approach imaging sequence before insertion into orbit. The images show the approximate color of Eros as it would be seen with the naked eye.” Click on the image to enlarge it. Credit
NASA/JPL/JHUAPL. Caption from: https://eros2019.imcce.fr/eros.html via Google Translate.

By the way, the Roman equivalent to Eros was the god Cupid, whose love dart is the constellation Sagitta, which resides within the Summer Triangle of bright stars, to be seen in the evening sky four months from now.

I’ll end with a Valentine heart. The red color is real, it’s due to hydrogen.

Heart Nebula

IC 1805 (Heart Nebula) Credit: s58y [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)%5D, via Wikimedia Commons.

11/23/2021 – Ephemeris – NASA to launch a mission to crash into an asteroid overnight tonight

November 23, 2021 Comments off

This is Ephemeris for Tuesday, November 23rd. Today the Sun will be up for 9 hours and 17 minutes, setting at 5:07, and it will rise tomorrow at 7:51. The Moon, half-way from full to last quarter, will rise at 8:17 this evening.

As of last Sunday night, it was GO for launch of NASA’s DART Mission at 1:21 am Eastern Standard Time tomorrow morning on a Falcon 9 rocket from Vandenberg Space Force Base. DART stands for Double Asteroid Redirection Test. The DART spacecraft is to smash into a small asteroid named Dimorphos, that slowly orbits another somewhat larger asteroid, Didymos. Dimorphos orbits at only 7 inches per second, so even the smallest impact should alter the orbit noticeably. About a week before the planned collision, DART will release a small CubeSat to arrive 3 minutes after the collision to survey the crash site. In 2024 the European Space Agency will launch a satellite to survey the asteroid pair and note any long-term effects, to see if this technique for diverting asteroids is feasible.

Addendum

DART at Didymos and Dimorphos to scale

DART spacecraft with Dimorphos and Didymos. The DART spacecraft is not to scale with the asteroids. See below. CREDIT: NASA/JHUAPL

Dart and asteroids to scale

Dart and asteroids to scale with terrestrial landmarks. Credit: NASA/JHUAPL

11/19/2021 – Ephemeris – The Earth is being stalked by an asteroid

November 19, 2021 Comments off

This is Bob Moler with Ephemeris for Friday, November 19th. Today the Sun will be up for 9 hours and 25 minutes, setting at 5:10, and it will rise tomorrow at 7:46. The Moon, at full today, will rise at 5:23 this evening.

We’re being stalked by an asteroid. Its name is, and I’m not going to say it twice: Kamo`oalewa or 2016 HO3 for short. It was discovered with the Pan-STARRS telescope at Haleakala on Maui on April 27, 2016. Which explains the name. It’s Hawaiian for something that oscillates. It’ll make big circles in the evening sky for a while, then it will retreat while the Earth moves ahead of it and almost overtakes it. It will oscillate in the morning sky for a while, I mean years. Then it will head around the Earth’s orbit and go back to the evening or trailing part of the orbit and the sky and do it all over. It never seems to get closer than 5 million miles away. Some astronomers think it might be a chunk of the Moon blasted off by an asteroid impact.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

2016HO3 (Kamo`oalewa) orbit

Kamo`oalewa (2016 HO3) orbit around the Sun, and shows how it interacts with the Earth. Credit: NASA/JPL.

Check out all the weirdness that is Kamo’oalewa here: https://en.wikipedia.org/wiki/469219_Kamo’oalewa.

10/21/2021 – Ephemeris – Defending the planet

October 21, 2021 Comments off

This is Ephemeris for Thursday, October 21st. Today the Sun will be up for 10 hours and 41 minutes, setting at 6:47, and it will rise tomorrow at 8:07. The Moon, 1 day past full, will rise at 7:29 this evening.

This is the 4th program in 8 days here on Ephemeris about asteroids. A possible collision of an asteroid or comet has been on our collective minds since the 20-some odd pieces of Comet Shoemaker-Levy 9 hit Jupiter in July 1994. In 2016 NASA established the Planetary Defense Coordination Office to manage its ongoing planetary defense efforts. Its mission is to provide early detection of potentially hazardous objects that can come within 5 million miles of the Earth’s orbit and a size large enough to cause significant damage. Asteroid sizes would be 30 to 50 meters in diameter, that’s 90 to 150 feet in diameter or larger. It will track and issue warnings of these objects when found. It will coordinate responses to any impact threat.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT-4 hours). They may be different for your location.

Addendum

Planetary Defense Coordination Office

What the Planetary Defense Coordination Office does. Credit: NASA.

10/19/2021 – Ephemeris – Introducing the DART mission

October 19, 2021 Comments off

This is Bob Moler with Ephemeris for Tuesday, October 19th. Today the Sun will be up for 10 hours and 47 minutes, setting at 6:50, and it will rise tomorrow at 8:05. The Moon, 1 day before full, will set at 7:54 tomorrow morning.

Last Saturday morning, the Lucy mission to Jupiter’s Trojan Asteroids was launched. These asteroids are forever locked in Jupiter’s orbit and will never be a hazard to the Earth. Next month, NASA will hopefully launch a mission to a much closer asteroid Didymos, which is considered a potentially hazardous asteroid. The asteroid has a diameter of a bit less than a half mile (780 meters). It also has a satellite named Dimorphos, which has acquired the nickname Didymoon, 520 feet (160 meters) in diameter. The mission called DART for Double Asteroid Redirection Test will see how the impact of a spacecraft hitting the small Didymoon will affect its orbit around the larger asteroid.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT-4 hours). They may be different for your location.

Addendum

The DART Mission

The Double Asteroid Redirection Test (DART) mission is NASA’s contribution to the international Asteroid Impact & Deflection Assessment (AIDA) program to determine the effectiveness of a spacecraft kinetic impact of an asteroid in altering its orbit. Credit: NASA.

03/29/2021 – Ephemeris – NASA will fly spacecraft Psyche to asteroid 16 Psyche

March 29, 2021 1 comment

This is Ephemeris for Monday, March 29th. Today the Sun will be up for 12 hours and 38 minutes, setting at 8:07, and it will rise tomorrow at 7:26. The Moon, 1 day past full, will rise at 9:28 this evening.

In the summer of 2022, about 15 months from now, NASA will launch a spacecraft called Psyche on a SpaceX Falcon Heavy rocket to 16 Psyche, an asteroid. 16 Psyche is a very special asteroid. It is mostly made of iron and nickel like iron meteorites and the cores of planets like the Earth. The spacecraft will be launched to get a gravity assist from Mars and will be using an ion engine to make its way to 16 Psyche and orbit it at various altitudes to see if it really is the remnant core of a protoplanet that was destroyed by collisions with other large asteroids. It would be of great interest for the future of asteroid mining companies for the precious metals it might contain. It’s big and has an average diameter of 140 miles (225 kilometers).

<p value="<amp-fit-text layout="fixed-height" min-font-size="6" max-font-size="72" height="80">The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

An artist's concept of the Psyche spacecraft orbiting the asteroid 16 Psyche
An artist’s concept of the Psyche spacecraft orbiting the asteroid 16 Psyche. The spacecraft will be sent past Mars for a gravity assist, and also use ion thrusters to speed it on its three and a half journey to the asteroid. Credit: NASA/JPL-Caltech/Arizona State Univ./Space Systems Loral/Peter Rubin

10/29/2020 – Ephemeris – A look at Bennu the asteroid

October 29, 2020 Comments off

This is Ephemeris for Thursday, October 29th. Today the Sun will be up for 10 hours and 17 minutes, setting at 6:34, and it will rise tomorrow at 8:18. The Moon, 2 days before full, will set at 7:06 tomorrow morning.

Tonight we will have Mars appearing above the bright gibbous Moon in the evening sky. Out in space NASA’s OSIRIS-REx spacecraft is still in the vicinity of the tiny asteroid Bennu. The asteroid is about 60 percent the distance between the Earth’s and Mars’ orbits, but on the far side of the Sun from us. This is why it will take 3 years to return the sample to the Earth. Bennu is small, only 743 feet (226.5 meters) in diameter. And is a rubble pile asteroid with lots of empty voids between the rocks. The sampler instead of stopping at the surface, punched into the asteroid surface a bit. Bennu was picked because is a potential hazardous asteroid and is a particularly primitive type of asteroid.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Bennu and Earth showing distance

Inner Solar when OSIRIS REx took its sample from Bennu. Bennu’s official designation is 101955 Bennu. The number designation is the consecutive number it is given when placed on the official list of asteroids and dwarf planets when its orbit is determined. Notice that it was on the other side of the Sun. Credit NASA’s Eyes app.

The asteroid Bennu is 743 feet (226.5 meters) in diameter. It is a carbonaceous asteroid. OSIRIS-REX has already discovered water bearing clays on its surface. Credit NASA

10/27/2020 – Ephemeris – NASA’s cup runneth over with asteroid bits

October 27, 2020 Comments off

This is Ephemeris for Tuesday, October 27th. Today the Sun will be up for 10 hours and 23 minutes, setting at 6:37, and it will rise tomorrow at 8:16. The Moon, half way from first quarter to full, will set at 5:04 tomorrow morning.

One week ago the NASA’s OSIRIS Rex spacecraft unfolded its sampling arm, and folded up it solar panels so as to look like a one legged stork landing and touched a small level patch of small jagged rocks on the tiny asteroid Bennu. A nitrogen bottle was triggered to blow soil and small rocks into a cylindrical container which created quite a blizzard of small rocks. A flap on the collection device was supposed to close, keeping the collected bits in, but was propped open by a large rock, so some of the contents started to leak out. Now flight controllers must gently maneuver the collector into the return canister without losing too much of the contents. The sample canister is expected to return to Earth in 2023.

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Artist depiction OSIRIS-REx TAG (Touch and Go)

Artist depiction OSIRIS-REx TAG (Touch and Go) from video. Credit NASA.

Animated GIF of the actual sample collection

Animated GIF of the actual sample collection TAG (Touch and Go). Credit NASA.

For more information go to https://www.nasa.gov/osiris-rex