October 1, 2023
Sunday, October 1, 2023
The OSIRIS-REx sample return capsule landed safely last Sunday morning (September 24) with its precious cargo of pieces of the primitive asteroid, Bennu. In honor of that and the other asteroid missions we’re celebrating this asteroid season, on Thursday, October 5, the William M Thomas Planetarium will present “Incoming!” about asteroid and comet impacts on Earth. The doors open at 7 p.m. and are locked when the show begins at 7:30 p.m. Later this month on October 19, “Black Holes” will be on the dome. See the Planetarium’s new website for more information about the shows and purchasing tickets.
The landing and recovery of the OSIRIS-REx sample return capsule (SRC) was a great illustration of what we can do with a lot of preparation, testing, and practice. The practice included using computer simulators and real-world work out in the field. The SRC landed on the eastern edge of the landing ellipse that was calculated many months ago using the average atmosphere conditions for the parts of the U.S. it would be flying over. When the team inputted in the atmosphere conditions that were measured just before the SRC reached Earth’s atmosphere, they predicted that the SRC would land on the eastern edge of the landing ellipse.
The atmosphere computer models using the average conditions also predicted that it would take 13 minutes from hitting the top of the atmosphere at 27,650 mph to landing at a much gentler 11 miles per hour. Last Sunday the atmosphere was a bit denser from a recent storm system and it took just 10 minutes to travel to the surface. It was a good thing that the SRC computer was smart enough to deploy the parachute at a particular deceleration point instead of a particular time point or the parachute would have deployed too late!
On Tuesday, September 26, the team got their first look at what OSIRIS-REx collected from the asteroid. Sometime this week they will let us know how much was actually collected along with some very preliminary analysis. The analysis of the rock and dirt will continue for many, many years. About 70% will be stored away for future generations of scientists to analyze with as yet to be invented equipment and as yet to be developed new questions to ask. This is policy of all U.S. sample return missions that began with the lunar samples brought back by the Apollo astronauts over fifty years ago.
Tuesday was also the one-year anniversary of the DART impact mission that hit the near-Earth asteroid, Dimorphos. This coming Thursday, October 5 is when the launch window opens for the Psyche mission to explore the metal-core asteroid, Psyche. Of the approximately 500,000 asteroids known, only nine are metal-rich. The asteroid, Psyche is about 173 miles in diameter and it orbits within the main asteroid belt between Mars and Jupiter. The spacecraft Psyche will take almost six years to travel to Psyche using its ion engine. It will explore the asteroid for about two years.
The last event of the asteroid season will be the flyby on November 1 of the asteroid Dinkinesh by the Lucy spacecraft on its way out to the Trojan asteroid families that share an orbit with Jupiter. One group of the Trojans orbits 60 degrees ahead of Jupiter and the other group orbits 60 degrees behind Jupiter at the L4 and L5 gravitational balance points of the Jupiter-Sun system, respectively. Lucy will reach the L4 Trojans in 2027, exploring them for a couple of years before heading over to the L5 group, arriving in 2033.
On October 14, the moon will be exactly lined up with the sun to create a solar eclipse. However, the moon will be too far away to totally cover up the sun’s surface, so this will be an annular solar eclipse with up to 91% of the sun covered. Those in the path of annularity will still need to use special solar filters to avoid eye damage. The path of annularity is across the western U.S. from southern Oregon beginning at 9:13 a.m. PDT to northern Nevada to southern Utah to the middle of New Mexico to southern Texas by 12:03 p.m. CDT. The path continues to the Yucatan peninsula of Mexico, parts of Central America, and the northern end of South America. For us in Bakersfield, we’ll see a partial solar eclipse between 8:09 a.m and 10:48 a.m. with about 75% of the sun covered at the midpoint at 9:23 a.m.
In this evening’s sky the moon will be a waning gibbous right next to brilliant Jupiter. They will rise around 8:30 p.m. about ten minutes apart from each other (the moon first) at the west end of Taurus. As the night progresses, the moon will get farther apart from Jupiter, so the conjunction will be more spectacular the earlier you view it. Tomorrow night the moon will be right next to the Pleiades cluster at the shoulder of Taurus. At 9:30 p.m., the Summer Triangle stars will be nearly overhead—Deneb at the tail of Cygnus, Vega in Lyra, and Altair at the neck of Aquila. Saturn is at the western edge of Aquarius.
I hope to see you at one of the planetarium shows!
—
Nick Strobel
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
