An artistic view of light becoming matter. Credit: Gerd Altmann, via Pixabay
In 1905 Albert Einstein wrote four groundbreaking papers on quantum theory and relativity. It became known as Einstein’s annus mirabilis or wonderous year. One was on brownian motion, one earned him the Nobel prize in 1921, and one outlined the foundations of special relativity. But it’s Einstein’s last 1905 paper that is the most unexpected.
Over the past few weeks, there was quite a bit of excitement in the air at the NASA Jet Propulsion Laboratory in Pasadena, California, where mission controllers were prepping the Perseverance rover to acquire its first sample from the Martian surface. This mission milestone would be the culmination of years of hard work by a team of over 90 dedicated scientists and engineers.
The commands to commence operations to take its first sample (from drill site Roubion) were sent to the rover on Sol 164 (Thurs, Aug. 5th). On the morning of Friday, Aug. 6th, the team gathered to witness the sampling data come in. Everything appeared to be fine until they were notified a few hours later that the sample tube was empty! Since then, the rover’s science and engineering teams have been investigating what could have become of the sample.
One of the reasons the ISS is still alive and kicking is that it offers a unique environment for testing that is available nowhere, either on the Earth or off of it. Plenty of science experiments want to take advantage of that uniqueness. This week, a fresh crop of experiments was delivered to the ISS aboard a Northrop Grumman Cygnus resupply craft. They range from 3D printers to a high school science experiment with mold, and now they each have the opportunity to make use of the ISS’s microgravity environment.
As any good project manager will tell you, goals are necessary to complete any successful project. The more audacious the goal, the more potentially successful the project will be. But bigger goals are harder to hit, leading to an increased chance of failure. So when the team behind one of NASA’s most unique missions released a list of goals this week, the space exploration world took notice. One thing is clear – Dragonfly will not lack ambition.
This mosaic image of asteroid Bennu is composed of 12 images collected on Dec. 2, 2018, by the OSIRIS-REx spacecraft's PolyCam instrument from a range of 15 miles (24 kilometers). Credit: NASA/Goddard/University of Arizona
Asteroid Bennu is one of the two most hazardous known asteroids in our Solar System. Luckily, the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) spacecraft orbited Bennu for more than two years and gathered data that has allowed scientists to better understand the asteroid’s future orbit, trajectory and Earth-impact probability, and even rule out some future impact possibilities.
In the most precise calculations of an asteroid’s trajectory ever made, researchers determined Bennu’s total impact probability through the year 2300 is really small — about 1 in 1,750 (or 0.057%). The team’s paper says the asteroid will make a close approach to Earth in 2135, where Bennu will pose no danger at that time. But Earth’s gravity will alter the asteroid’s path, and the team identifies Sept. 24, 2182 as the most significant single date in terms of a potential impact, with an impact probability of 1 in 2,700 (or about 0.037%).
“The impact probability went up just a little bit, but it’s not a significant change,” said Davide Farnocchia, lead author of the paper, and scientist at the Center for Near Earth Object Studies at NASA’s Jet Propulsion Laboratory, speaking at a press briefing this week. Farnocchia added that means there is a 99.94% probability that Bennu is not on an impact trajectory.
“So, there is no particular reason for concern,” he said. “We have time to keep tracking the asteroid and eventually come to a final answer.”
101955 Bennu was discovered in 1999 by the Lincoln Near-Earth Asteroid Research Team. Since its discovery, Bennu has been extensively tracked with 580 ground-based optical astrometric observations. The asteroid made three relatively close passes of Earth in 1999, 2005, and 2011, during which the Arecibo and Goldstone radar stations collected a wealth of data about Bennu’s motion.
OSIRIS-REx discovered particles being ejected from asteroid Bennu shortly after arriving at the asteroid. Image Credit: NASA/Goddard/University of Arizona/Lockheed Martin
But OSIRIS-REx’s two-year reconnaissance and sample collection has provided crucial data about the 500-meter-wide asteroid, including some surprises. Scientists expected Bennu’s surface to be smooth and sandy, but the first images from OSIRIS-REx revealed a rugged boulder-field, littered with large rocks and loose gravel. The team also expected the asteroid to be geologically quiet, but just six days after arriving in orbit, the spacecraft observed the asteroid ejecting bits of rock, due to rocks on the asteroid cracking because of the day-night heat cycle. We also learned that Bennu has pieces of Vesta on it. The spacecraft also scooped up a sample of rock and dust from the asteroid’s surface in October of 2020, which it will deliver to Earth on Sept. 24, 2023, for further scientific investigation.
But OSIRIS-REx’s precise observations of Bennu’s motions and trajectory allowed for the best estimate yet of the asteroid’s future path.
“The OSIRIS-REx mission has provided exquisitely precise data on Bennu’s position and motion through space to a level never captured before on any asteroid,” said Lindley Johnson, planetary defense officer at NASA’s Planetary Defense Coordination Office at NASA.
The researchers took into account all kinds of small influences, including the tiny gravitational pull of more than 300 other asteroids, and the drag caused by interplanetary dust. They even checked to see if OSIRIS-REx pushed the asteroid off course when the spacecraft briefly touched its rocky surface with its Touch-And-Go (TAG) sample collection maneuver. But that event had a negligible effect, as expected.
The researchers especially focused on a phenomenon called the Yarkovsky effect, where an object in space would, over long periods of time, be noticeably nudged in its orbit by the slight push created when it absorbs sunlight and then re-emits that energy as heat. Over short timeframes, this thrust is minuscule, but over long periods, the effect on the asteroid’s position builds up and can play a significant role in changing an asteroid’s path.
“The Yarkovsky effect will act on all asteroids of all sizes, and while it has been measured for a small fraction of the asteroid population from afar, OSIRIS-REx gave us the first opportunity to measure it in detail as Bennu travelled around the Sun,” said Steve Chesley, senior research scientist at JPL and study co-investigator, in a press release. “The effect on Bennu is equivalent to the weight of three grapes constantly acting on the asteroid – tiny, yes, but significant when determining Bennu’s future impact chances over the decades and centuries to come.”
A diagram showing OSIRIS-REx’s sampling maneuver on October 20th, 2020. Image Credit: NASA/GSFC/UA
They also were able to better determine how the asteroid’s orbit will evolve over time and whether it will pass through a “gravitational keyhole” during its 2135 close approach with Earth. These keyholes are areas in space that would set Bennu on a path toward a future impact with Earth if the asteroid were to pass through them at certain times, due to the effect of Earth’s gravitational pull.
The team wrote in their paper that “compared to the information available before the OSIRIS-REx mission, the knowledge of the circumstances of the scattering Earth encounter that will occur in 2135 improves by a factor of 20, thus allowing us to rule out many previously possible impact trajectories.”
“The orbital data from this mission helped us better appreciate Bennu’s impact chances over the next couple of centuries and our overall understanding of potentially hazardous asteroids – an incredible result,” said Dante Lauretta, OSIRIS-REx principal investigator and professor at the University of Arizona. “The spacecraft is now returning home, carrying a precious sample from this fascinating ancient object that will help us better understand not only the history of the solar system but also the role of sunlight in altering Bennu’s orbit since we will measure the asteroid’s thermal properties at unprecedented scales in laboratories on Earth.”
As we all anticipate the launch of the James Webb Space Telescope (JWST) later this year (hopefully), LEGO designers are hoping for a “launch” of their own. A new LEGO design of JWST is currently gathering supporters on the LEGO Ideas website. If it gets enough support, LEGO will review it and possibly create it.
As of today (August 12, 2021), the idea has just under 1,500 supporters, with the goal of 10,000. If you want your very own JWST model, cast your vote of support!
When it comes to finding exoplanets, size matters, but so does weight. The larger and heavier the planet, the more likely they will be discovered by the current crop of telescopes. Both the techniques to find exoplanets and the telescopes using those techniques are biased toward larger, heavier planets. So when even the current crop of telescopes manages to find one that is about half the mass of Venus, it is cause for celebration. That is precisely the size of the planet a team from the European Southern Observatory’s Very Large Telescope has found orbiting a star called L98-59.
Photos can’t do some places justice – nor can any level of sophisticated remote sensing. That seems to be the case for Gale Crater. Curiosity has been wandering around the crater for almost the last nine years. Scientists thought Gale crater was an old lakebed, and it was specifically chosen as a landing site to allow Curiosity to collect samples from such a lakebed. But new research from scientists at the University of Hong Kong shows that most likely, the samples Curiosity has been analyzing during its sojourn didn’t actually form in a lake.
In this series we are exploring the weird and wonderful world of astronomy jargon! Adjust your eyeglasses to read about today’s topic: adaptive optics!
If you’re a fan of the Search for Extraterrestrial Intelligence (SETI) and the Fermi Paradox, then it’s likely you’ve heard of a concept known as the Great Filter. In brief, it states that life in the Universe may be doomed to extinction, either as a result of cataclysmic events or due to circumstances of its own making (i.e., nuclear war, climate change, etc.) In recent years, it has been the subject of a lot of talk and speculation, and not just in academic circles.
Stephen Hawking and Elon Musk have also weighed in on the issue, claiming that humanity’s only chance at long-term survival is to become “interplanetary.” Addressing this very possibility, a research team led by NASA’s Jet Propulsion Laboratory (JPL) recently created a timeline for potential human expansion beyond Earth. According to their findings, we have the potential of going interplanetary by the end of the century and intragalactic by the end of the 24th!
