Geography

Theia: The Impact That Brought Water to a Forming Earth

By Jonathan Bala February 7, 2025

Theia: The Impact That Brought Water to a Forming Earth

Water on Earth may have arrived in several late-stage events after the colossal impact of Theia, fundamentally reshaping our views on planetary formation and the origin of life.

Summary

Theia Impact: A Mars-sized body collided with early Earth, initiating the Moon’s formation.
Water Delivery Mechanism: Instead of a single event, water arrived in small doses through later accretion processes involving asteroids and comets.
Scientific Insights: Isotopic analysis of meteorites and terrestrial rocks has provided new clues on where Earth’s building blocks originated.
Collaborative Research: Multiple institutions have contributed to advancing our understanding of Earth’s formation, including work by Rutgers University and other renowned centers.
Life’s Foundations: The timing and nature of water delivery are pivotal for the emergence and evolution of life on Earth.

Theia The Impact That Brought Water to a Forming Earth — This is a picture created by an artist. It shows a huge collision that changed the Earth. This collision also made the Moon. Credit for the image goes to NASA and JPL-Caltech.

Introduction

The early history of our planet is a tale of cosmic collisions and miraculous deliveries. Among the most dramatic events in Earth’s history is the collision with a Mars-sized body known as Theia. This colossal impact not only resulted in the formation of the Moon but also set the stage for the arrival of water on Earth. Over billions of years, water has played a crucial role in shaping the planet’s geology and the development of life. Researchers continue to study this event to unravel the mysteries behind the origins of our world.

The widely accepted theory suggests that shortly after the birth of the Sun from a swirling nebula, the remaining dust and gas formed a protoplanetary disk. Within this disk, various celestial bodies began to coalesce under gravity. Theia emerged as one of these bodies, and its eventual collision with early Earth marked a turning point in the planet’s evolution.

The Theia Impact Event

In the tumultuous environment of the early Solar System, collisions were common. Theia, a protoplanet approximately the size of Mars, is believed to have struck the early Earth around 4.5 billion years ago. This violent impact ejected vast amounts of material into orbit around Earth, which eventually coalesced to form the Moon. The repercussions of this event were profound. Not only did the collision dramatically alter Earth’s rotation and structure, but it also created conditions that may have allowed water and other volatile compounds to accumulate.

The aftermath of the impact created a dynamic stage for cosmic events that followed. Scientists used to believe that the Moon-forming impact brought most of Earth’s water. However, new research shows this might not be true. Water may have arrived on Earth in a later phase. This later period involved several small impacts. Water-rich asteroids and comets hit the young planet. These impacts brought essential elements like water to Earth.

Water Delivery to a Forming Earth

Water is the cornerstone of life, and understanding how it arrived on Earth is essential to the field of planetary science. Recent studies, including those published on ScienceDirect, suggest that the bulk of water did not come from the initial Theia impact. Instead, the planet received water in smaller increments during the late stages of its formation—a phase known as late accretion.

The prevailing theory is that after the Moon had formed, a series of smaller impacts delivered water to Earth. Research featured in Rutgers News highlights how isotopic studies of meteorites and terrestrial rocks have provided evidence for this process. Scientists, including experts such as Katherine Bermingham, have analyzed the isotopic composition of elements like molybdenum. Their work shows that the chemical signatures in Earth’s rocks more closely resemble those found in meteorites from the inner Solar System rather than those from the outer regions where water and volatiles are more common.

A key discovery was made when comparing the isotopic ratios of molybdenum in meteorite samples from institutions like the Smithsonian National Museum of Natural History with those measured in rocks from various parts of the globe. These findings provide a compelling case that the water present on our planet arrived in stages rather than in a single, dramatic event.

Scientific Investigations

Researchers from diverse institutions, such as Rutgers University and PhAB at the University of Oslo, have worked together to decode the early history of water on Earth. Their investigations involve detailed isotopic analyses and comparisons of extraterrestrial materials. A significant portion of this research centers on understanding the non-carbonaceous nature of late-stage accretion, a subject discussed in a paper published in Geochimica et Cosmochimica Acta.

This insight highlights the importance of knowing both when water was delivered and how it was delivered. Scientists compared data from meteorites with samples from Earth. They collected these Earth samples from places like Greenland, South Africa, Canada, the United States, and Japan. They all agreed from these studies that Earth’s water came after the Moon was formed. This idea challenges what people thought before.

Data and Timeline

Below are two tables that help illustrate the timeline of events and the comparative isotopic signatures that support the late accretion theory.

Table 1: Timeline of Theia Impact and Water Delivery

Event	Time (Billion Years Ago)	Description
Formation of the Sun	4.6	The Sun forms from the collapse of a giant molecular cloud.
Theia Impact	4.5	A Mars-sized body collides with Earth, leading to the Moon’s formation.
Late Accretion Phase	4.4 – 4.3	Smaller impacts deliver water and other volatiles to the Earth after the Moon has formed.
Stabilization of Earth	4.3	Earth’s environment becomes more conducive to the emergence of life.

Table 2: Comparison of Isotopic Signatures

Sample Type	Isotopic Signature	Source Region
Inner Solar System Rocks	Enriched in specific isotopes	Formed close to the Sun
Meteorites (NC group)	Similar to Earth’s rocks	Originated from the drier inner Solar System
Meteorites (CC group)	Higher volatile content	Formed in the outer Solar System

Implications for Life

The timing of water delivery is critical when considering the origins of life on Earth. Water, along with energy and essential chemical building blocks, set the stage for biochemical processes that eventually led to life. The notion that water arrived in small increments during late accretion implies that Earth’s habitability developed over an extended period rather than as a sudden consequence of the Theia impact.

The introduction of water was gradual. This process led to more complex geochemical interactions. Geochemical interactions are chemical reactions between the Earth’s crust and other elements like water. These interactions might have created a stable environment. In such an environment, organic molecules could form and change over time. Organic molecules are basic building blocks of life. The research challenges what we assumed before. It also offers new possibilities for finding life on other planets. As we explore exoplanets, understanding Earth’s early history becomes even more important. Exoplanets are planets outside our solar system that might host life.

Fun Facts

Theia was named after a Titaness in Greek mythology, reflecting its monumental role in shaping the Earth.
The Moon is the fifth largest natural satellite in the Solar System.
Late accretion is a process observed on other planets and moons, highlighting common themes in planetary evolution.
Isotopic analysis is a powerful tool that helps scientists trace the origins of materials in the Solar System.

References

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Space Exploration

The Cataclysmic Birth of Earth’s Meteorites: What Science Reveals

By Jonathan Bala October 16, 2024

The Cataclysmic Birth of Earth’s Meteorites: What Science Reveals

Meteorites provide crucial information about the formation and evolution of our solar system. Most of Earth’s meteorites originate from a few collisions within the asteroid belt, with one major event occurring around 470 million years ago. This discovery highlights the importance of studying these ancient space rocks to better understand the solar system’s history.

Summary

Most meteorites on Earth originate from a few collisions in the asteroid belt.
Seventy percent of Earth’s meteorites are ordinary chondrites, specifically H and L chondrites.
A collision that occurred 470 million years ago created the L chondrites.
H chondrites come from multiple impacts, including those from the Koronis and Karin asteroid families.
These findings suggest that Earth’s meteorite collection is biased, limiting our understanding of the solar system.
Further space missions are necessary to investigate other asteroid types and gain a broader perspective.
The Massalia family of asteroids is a major contributor to Earth’s L chondrite meteorites.
Research reveals that another impact around 40 million years ago sent debris from the Massalia family to Earth.

A science fiction edit of a man standing in a field as meteorites speed towards the earth at night with the stars in the sky — small metal meteorite mineral isolated on the white background

Introduction

Meteorites are fragments of celestial bodies that have fallen to Earth, providing a rare glimpse into the early history of our solar system. They are ancient messengers, bearing information from the formation of planets, moons, and asteroids. But how much do we truly know about where these meteorites come from?

Recent scientific research has unveiled an astonishing fact: most of Earth’s meteorites can be traced back to just a few collisions within the asteroid belt, the region between Mars and Jupiter that is home to countless rocky remnants of the early solar system. Among these, one particularly cataclysmic collision stands out—a massive impact that occurred approximately 470 million years ago, which produced a large portion of the meteorites we observe today.

What Are Meteorites?

Meteorites are extraterrestrial rocks that survive their journey through Earth’s atmosphere and reach the surface. These rocks come in various types, but the most common are ordinary chondrites, making up 70% of all meteorite falls.

Types of Chondrites

Type	Description
H Chondrites	Rich in metal and less oxidized.
L Chondrites	Contain fewer metals and are more oxidized.

Scientists categorize meteorites based on their mineral composition and structure. Chondrites, for example, are composed of small spherical grains called chondrules. Ordinary chondrites are the most abundant, divided into H and L types.

The Birth of L Chondrites: 470 Million Years Ago

The discovery that L chondrites originated from a cataclysmic collision that occurred approximately 470 million years ago was groundbreaking. These meteorites likely came from a giant asteroid at least 100 kilometers in diameter. The collision sent shockwaves through the asteroid, scorching and altering the material before fragments were blasted into space. Over millions of years, these fragments found their way to Earth.

Using NASA’s Infrared Telescope Facility in Hawaii, scientists identified the Massalia family of asteroids as the source of L chondrites. This group of asteroids formed around 500 million years ago after breaking off from a larger parent body. One asteroid in the Massalia family is about 140 kilometers long, matching the size of the parent body that gave birth to the L chondrites.

The precision with which scientists can now trace meteorites back to their source is remarkable. The identification of the Massalia family as the origin of L chondrites provides vital context for understanding how the solar system’s building blocks came together to form planets, moons, and other celestial bodies.

How Scientists Rewind Time

One of the most fascinating aspects of this discovery is the time-rewinding technique used by researchers to trace the orbits of asteroids. By analyzing the trajectories of asteroids and meteorites, scientists can reconstruct their past orbits, effectively turning back the cosmic clock to determine where and when the impact occurred.

The findings suggest that the Massalia family of asteroids was born from a single cataclysmic impact that shattered a large parent body around 470 million years ago. This event released a cascade of debris into the asteroid belt, much of which eventually found its way to Earth in the form of meteorites.

The Origins of H Chondrites: A Tale of Two Collisions

While L chondrites have been traced to a single collision, the story of H chondrites is more complex. H chondrites are thought to come from two distinct impact events. The first occurred approximately 7.6 million years ago, involving the Koronis asteroid family. The second event, dated to around 5.8 million years ago, involved the Karin family of asteroids.

Together, these two collisions produced the H chondrites that make up much of Earth’s meteorite collection today. By analyzing the mineral composition and orbital dynamics of these asteroids, researchers were able to trace the origins of H chondrites to these specific events.

Bias in Earth’s Meteorite Collection

While these discoveries are exciting, they also reveal a potential bias in Earth’s meteorite collection. Seventy percent of meteorites on Earth are ordinary chondrites, and most of these come from just a handful of asteroids. This means that our current understanding of meteorites may be skewed, as we are only sampling a small fraction of the asteroid belt.

Sara Russell, a planetary scientist at London’s Natural History Museum, points out that the asteroid belt is home to a wide variety of objects, each offering unique insights into the solar system’s history. She warns that we may be missing out on the bigger picture:
“Maybe we’re only just seeing a tiny fraction of them through our meteorites.”

The solution? Space missions. By sending spacecraft to study asteroids up close, we can gain a more comprehensive understanding of the solar system’s early days. NASA’s OSIRIS-REx mission to the asteroid Bennu is a prime example of this approach. The spacecraft collected a sample from Bennu’s surface, which could provide new insights into the origins of meteorites and the solar system itself.

Future Exploration: Expanding Our Understanding

Mission	Purpose
OSIRIS-REx	To return samples from the asteroid Bennu for study.
Hayabusa2	Collected samples from the asteroid Ryugu.

As we continue to explore the cosmos, more missions like OSIRIS-REx and Hayabusa2 will be essential. These missions allow us to directly sample asteroids and bring back pristine material for study, providing a more diverse and representative collection of meteorites.

Fun Facts About Meteorites

Meteorites can travel at speeds of up to 160,000 miles per hour as they hurtle toward Earth.
The largest meteorite ever found, Hoba, weighs approximately 66 tons and is located in Namibia.
Some meteorites contain traces of amino acids, the building blocks of life.
Meteor showers are caused by streams of meteoroids entering Earth’s atmosphere at the same time.

The study of meteorites offers a unique window into the early solar system, revealing the tumultuous history of the planets and asteroids that once collided and coalesced to form the celestial bodies we observe today. The discovery that most of Earth’s meteorites come from just a few collisions highlights the need for continued exploration of the asteroid belt to gain a more complete understanding of our cosmic origins.

References

#Meteorites, #Asteroids, #SpaceExploration, #SolarSystem, #NASA, #AsteroidBelt, #OSIRISREx, #Hayabusa2, #HChondrites, #LChondrites, #KoronisFamily, #KarinFamily, #SpaceMissions, #AstroScience, #MeteorShowers

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Space Exploration

Hera Mission: Europe Launches to Investigate Asteroid Hit by NASA

By Jonathan Bala October 11, 2024

Hera Mission: Europe Launches to Investigate Asteroid Hit by NASA

The Hera mission by the European Space Agency (ESA) aims to examine the aftermath of NASA’s DART mission, which struck the asteroid Dimorphos in 2022. Hera’s findings could help refine planetary defense strategies, protecting Earth from future asteroid threats. The mission’s success may establish new international efforts to shield our planet from asteroids.

Summary

Hera Mission launched by the European Space Agency (ESA) on October 7, 2024, aboard a SpaceX Falcon 9 rocket from Florida.
Main target: Investigate the impact of NASA’s DART mission on the binary asteroid system Didymos and its moon Dimorphos.
NASA’s DART mission successfully collided with Dimorphos in 2022, reducing its orbital period by 33 minutes.
Hera will confirm whether DART’s impact altered the moon’s shape and surface structure.
Two cubesats – Milani and Juventas – accompany Hera and will examine Dimorphos’ minerals, structure, and gravity.
Planetary defense: Hera is part of an international strategy to protect Earth from asteroid impacts.
The mission will include a flyby of Mars in 2025 for a gravity assist.
ESA Director General Josef Aschbacher emphasized the global importance of planetary defense missions like Hera.
SpaceX used all of the Falcon 9 booster’s fuel, so the first stage did not return for landing.
DART’s impact created a crater on Dimorphos; Hera will measure the depth and size of this crater.
The mission will arrive at Dimorphos in 2026, completing a multimillion-mile journey.
Focus areas: Measuring the crater, confirming orbital changes, and analyzing surface minerals.
The Falcon 9 booster, used for multiple prior missions, was retired after Hera’s launch.
Hera’s data will help refine models for future asteroid deflection missions.
DART’s success shows that asteroids can be redirected, bolstering global planetary defense efforts.

Hera Mission – Europe Launches to Investigate Asteroid Hit by NASA

In an age where space exploration is more focused on planetary defense, humanity has taken a significant step toward safeguarding Earth. On October 7, 2024, the European Space Agency (ESA) launched the Hera mission, marking the next phase in the study of asteroids. Hera will investigate the binary asteroid system Didymos and its smaller moon Dimorphos, which NASA’s DART mission impacted in 2022. The goal is to collect critical data on planetary defense strategies that may one day protect Earth from rogue space rocks.

NASA’s DART (Double Asteroid Redirect Mission) struck Dimorphos to test if an asteroid’s orbit could be altered. The mission succeeded, reducing Dimorphos’ orbit around Didymos by 33 minutes. Now, Hera will build on DART’s success by conducting a more detailed study of the asteroid’s changes, surface characteristics, and impact crater.

Mission Overview

The Hera mission was launched aboard a SpaceX Falcon 9 rocket from Cape Canaveral at 10:52 a.m. EDT. Unlike most SpaceX launches, the first stage of the Falcon 9 did not return to Earth for reuse. To ensure Hera had enough fuel to reach its target, the booster burned up its reserves entirely, leading to a planned disposal in the ocean. This particular Falcon 9 booster had been used in 23 previous missions, including Starlink satellite launches, NASA astronaut flights, and rideshare missions.

Hera’s journey will take it through the solar system, passing by Mars in 2025 for a gravity assist before heading to its final destination – the binary asteroid system of Didymos and Dimorphos.

Why Dimorphos?

The choice of Dimorphos as the mission’s target is strategic. The DART impact on the asteroid in 2022 was the first attempt by humanity to intentionally change the orbit of a celestial body. DART’s success demonstrated the potential of using kinetic impactors to deflect an asteroid’s path, offering hope that we could one day protect Earth from a catastrophic collision.

“We are now going back to Didymos and Dimorphos, we’ll make those measurements, and we’ll make the world a safer place from the impact of asteroids.”
– Alan Fitzsimmons, Hera Science Team Board Member

Hera will examine whether the DART impact did more than alter Dimorphos’ orbit. It will investigate whether the impact changed Dimorphos’ surface composition or even its shape. Additionally, the mission will measure the size and depth of the crater left by DART’s collision, further refining models for future asteroid deflection strategies.

International Planetary Defense

One of the most exciting aspects of Hera is its contribution to the growing field of planetary defense. Earth is constantly under the threat of potential impacts from asteroids, and understanding how to deflect or destroy these bodies is vital to our survival. Hera is part of a larger, international effort to protect our planet. As ESA Director General Josef Aschbacher put it:

“Defending our planet from space threats involves countries from all around the world. I am very pleased about this cooperation. The Hera spacecraft is a project by ESA, which stands for the European Space Agency. This spacecraft is leading Europe’s efforts to protect Earth from potential dangers from space.”

While the NASA DART mission proved that an asteroid could be deflected, Hera will refine our understanding of how such impacts work and how effective they can be.

What Will Hera Do?

Once Hera arrives at Dimorphos in 2026, it will begin its mission of measuring the impact crater created by DART. Scientists are eager to learn how much material was ejected during the collision and how deep the crater penetrated into the asteroid’s surface.

Mission Objectives

Crater Measurement: Hera will assess the depth and diameter of the crater caused by DART.
Orbital Analysis: Confirm the orbital changes caused by DART’s impact.
Surface Examination: Analyze the composition of surface minerals and look for any shape alterations in Dimorphos.
Cubesat Exploration: Hera carries two smaller satellites, Milani and Juventas, which will examine Dimorphos’ gravity, structure, and surface features.
Refining Models: The data from Hera will help scientists refine their models for asteroid deflection techniques, improving future missions.

The Cubesats: Milani and Juventas

A significant part of Hera’s mission involves two smaller spacecraft: Milani and Juventas. These cubesats will deploy once Hera reaches Dimorphos and begin their own investigations. Milani will focus on the surface composition, examining minerals and the asteroid’s structure. Juventas, on the other hand, will use a radar instrument to explore the internal structure of Dimorphos. This will provide insights into how asteroids are formed and how they behave when struck by external forces like DART.

Technical Aspects of the Mission

Hera Mission Overview	Key Information
Launch Date	October 7, 2024
Launch Vehicle	SpaceX Falcon 9
Target Arrival Date	2026
Target	Dimorphos
Accompanying Spacecraft	Milani and Juventas

The Hera spacecraft is equipped with various instruments to help it achieve its goals, including high-resolution cameras to capture detailed images of the asteroid’s surface, laser altimeters for measuring topography, and spectrometers to analyze the surface minerals.

The Importance of Hera

The Hera mission is an essential follow-up to NASA’s DART mission. Together, these missions demonstrate the international collaboration required to tackle the issue of planetary defense. Hera’s findings will contribute significantly to our understanding of how to deflect dangerous asteroids. In addition, the mission’s data will be shared with scientists worldwide, fostering a global approach to asteroid monitoring and defense.

Scientific Impact

Expected Scientific Outcomes	Details
Crater Analysis	Size, depth, and material ejected
Orbital Alteration Confirmation	Measuring Dimorphos’ new orbit
Surface and Internal Composition	Analyzing minerals and internal structure
Planetary Defense Models	Refining deflection models

By 2026, when Hera arrives at Dimorphos, humanity will have taken a crucial step toward defending our planet from space threats. The $398 million mission is not just a scientific endeavor but a global safeguard for the future.

References

NASA’s DART Mission

#HeraMission, #PlanetaryDefense, #Dimorphos, #ESA, #NASADART, #SpaceX, #AsteroidDeflection, #Falcon9, #ESAPlanetaryMission, #MilaniAndJuventas, #BinaryAsteroidSystem, #Didymos

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Space Exploration

NASA Shuts Down NEOWISE Telescope as Sun Draws It to a Fiery End

By Jonathan Bala August 10, 2024

NASA Shuts Down NEOWISE Telescope as Sun Draws It to a Fiery End

NEOWISE, originally WISE, was a NASA space telescope designed to detect infrared signals from space objects, including near-Earth asteroids and comets.
Launched in 2009, the telescope vastly outlived its intended seven-month mission, operating for over 15 years and making significant discoveries.
NEOWISE detected over 200 previously unknown near-Earth objects (NEOs), including 25 new comets and provided valuable data on 44,000 other objects.
The telescope was retired on July 31, 2024, due to the increased solar activity that will eventually drag it into Earth’s atmosphere, where it will burn up.
A successor mission, the NEO Surveyor, is planned for launch in 2027 to continue the work of NEOWISE, with more advanced technology to detect asteroids near the sun’s glare.
The end of NEOWISE leaves a temporary gap in planetary defense, but ground-based telescopes will continue to monitor near-Earth objects.

NASA Shuts Down NEOWISE Telescope as Sun Draws It to a Fiery End

NASA’s NEOWISE telescope, a remarkable instrument that spent 15 years scanning the skies for near-Earth objects, has reached the end of its journey. Originally launched as the Wide-field Infrared Survey Explorer (WISE) in 2009, the telescope far exceeded its initial expectations, making groundbreaking discoveries and providing critical data for planetary defense. As the sun’s activity reaches its peak, the satellite is being pulled towards Earth, where it will ultimately burn up in the atmosphere, marking the end of an era for NASA’s asteroid-hunting efforts.

The Origins and Evolution of NEOWISE

NEOWISE began its life as WISE, a mission with a relatively simple goal: to map the entire sky in infrared light. Infrared astronomy allows scientists to see objects that are otherwise invisible in visible light, particularly cold and distant objects in space. When WISE was launched, its primary mission was to observe distant galaxies, stars, and other cosmic phenomena, contributing to our understanding of the early universe.

However, the capabilities of WISE soon exceeded expectations. Its sensitivity to infrared light made it an excellent tool for detecting near-Earth objects (NEOs), such as asteroids and comets that might pose a threat to our planet. Recognizing this potential, NASA extended WISE’s mission in 2010 and rebranded it as NEOWISE in 2013, focusing its efforts entirely on planetary defense.

NEOWISE’s Mission and Achievements

Over the course of its extended mission, NEOWISE became an invaluable asset for NASA. The telescope detected more than 200 previously unknown near-Earth objects, including 25 new comets. It also gathered data on 44,000 other objects within our solar system, greatly enhancing our understanding of the space environment surrounding Earth.

One of NEOWISE’s most notable discoveries was the detection of comet C/2020 F3 (NEOWISE), a bright and spectacular comet that became visible to the naked eye in July 2020. This discovery captured the public’s imagination and highlighted the telescope’s enduring value, even as it approached the end of its operational life.

NEOWISE’s data has been crucial for mapping the orbits of near-Earth asteroids, which helps scientists assess the potential threat these objects might pose to our planet. According to NASA, more than 34,000 near-Earth asteroids have been cataloged, and none of them are expected to collide with Earth in the next 100 years.

The Inevitable End of NEOWISE

Despite its many successes, NEOWISE’s mission could not last forever. The spacecraft was originally designed for a seven-month mission, and although it managed to continue functioning for 15 years, the increasing activity of the sun, known as solar maximum, posed a significant threat. Without propellant to raise its orbit, NEOWISE has been gradually falling towards Earth, and it is expected to reenter the atmosphere and burn up by the end of 2024.

Amy Mainzer, a professor at the University of California, Los Angeles, and the principal investigator for both NEOWISE and its planned successor, NEO Surveyor, expressed her gratitude for the telescope’s extended mission. “This telescope has really outlived its original lifespan,” she said in an interview with Live Science. “We got so much more out of it than we were expecting to get.”

The Future of Asteroid Hunting: NEO Surveyor

While the end of NEOWISE marks a significant loss for NASA’s planetary defense efforts, the space agency is already planning the next phase of its mission to protect Earth from potential asteroid impacts. The NEO Surveyor is a next-generation space telescope designed to continue the work of NEOWISE, with even greater capabilities.

Scheduled for launch no sooner than 2027, the NEO Surveyor will perform full-sky scans every two weeks, significantly improving the detection of near-Earth objects. One of the key features of this new telescope will be its ability to search for asteroids located near the sun’s glare, a region that has long been considered a blind spot in planetary defense.

To achieve this, the NEO Surveyor will be equipped with a purpose-built solar shade, allowing it to observe asteroids that are difficult to detect with ground-based telescopes. This capability will be crucial for identifying “planet-killer” asteroids that could potentially impact Earth with little warning.

A Temporary Gap in Planetary Defense

With the shutdown of NEOWISE, there will be a temporary gap in NASA’s space-based planetary defense capabilities. Currently, there is no other space telescope dedicated entirely to hunting for near-Earth objects. However, NASA and the astronomical community are not entirely defenseless. Powerful ground-based observatories, such as the Catalina Sky Survey in Arizona and Pan-STARRS in Hawaii, continue to play a vital role in monitoring the skies for potential threats.

The Importance of Planetary Defense

The work of NEOWISE and the upcoming NEO Surveyor highlights the critical importance of planetary defense. While the odds of a catastrophic asteroid impact are low, the potential consequences are so severe that vigilance is necessary. The extinction of the dinosaurs is a stark reminder of what can happen when a large asteroid collides with Earth.

NASA works hard to protect our planet from cosmic threats. They focus on planetary defense. This includes watching near-Earth objects. NASA also looks for ways to move or destroy dangerous asteroids. One of their projects is the Double Asteroid Redirection Test (DART). In 2022, DART successfully changed an asteroid’s orbit. This shows that technology can help reduce these risks.

As NEOWISE prepares to make its final descent into Earth’s atmosphere, it’s important to reflect on the legacy of this remarkable space telescope. Originally intended for a brief mission to observe distant galaxies, NEOWISE exceeded all expectations, becoming a cornerstone of NASA’s planetary defense efforts. Its discoveries have deepened our understanding of the solar system and provided valuable data that will continue to inform future missions.

The impending launch of the NEO Surveyor promises to build on NEOWISE’s achievements, offering even greater capabilities for detecting and monitoring near-Earth objects. While there may be a temporary gap in space-based planetary defense, the work of ground-based observatories and the eventual deployment of the NEO Surveyor will ensure that Earth remains vigilant against the threat of asteroid impacts.

Tables

Table 1: Key Discoveries by NEOWISE

Object	Type	Year Discovered	Significance
C/2020 F3 (NEOWISE)	Comet	2020	Visible to the naked eye, captured public attention
2010 TK7	Asteroid	2010	First known Earth trojan asteroid
2020 AV2	Asteroid	2020	First asteroid found with an orbit entirely within Venus

Table 2: Comparison of NEOWISE and NEO Surveyor Capabilities

Feature	NEOWISE	NEO Surveyor
Launch Year	2009	2027 (planned)
Primary Mission Duration	7 months	5 years
Detection of NEOs	200+	Expected to detect thousands more
Field of View	47 arcminutes square	Full-sky scan every 2 weeks
Special Capabilities	Infrared detection	Detection near the sun’s glare

Source:

Autoevolution. “The Sun Is About to Kill a Space Telescope That Protects Our Planet. There’s No Saving It.” Autoevolution, 3 August 2023, https://www.autoevolution.com/news/the-sun-is-about-to-kill-a-space-telescope-that-protects-our-planet-there-s-no-saving-it-226100.html#agal_17. Accessed 10 August 2024.

Hashtags

#NASA, #NEOWISE, #Space, #Astronomy, #PlanetaryDefense, #Asteroids, #NEOSurveyor, #Infrared, #SpaceTelescope, #EarthSafety

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Space-Based Navigation

Space Facts: Understanding Outer Space and Its Boundaries

By Jonathan Bala June 4, 2024

Space Facts: Understanding Outer Space and Its Boundaries

Key Takeaways

Space is an incredibly vast and largely unexplored region that extends beyond Earth’s atmosphere. Our solar system is home to a diverse collection of celestial objects, including planets, moons, asteroids, and comets. The universe is estimated to be 13.8 billion years old and contains approximately 2 trillion galaxies. Significant discoveries and explorations have been made, enhancing our understanding of space and its many mysteries.

Summary

Space does not have a definitive boundary, but the Kármán line at 100 km is often used as a marker.
Temperatures in space are extremely cold, around −270.45 °C.
Space is a vacuum with very little matter and no sound.
There are about 100-400 billion stars in the Milky Way galaxy.
The universe is expanding and is about 13.8 billion years old.
There are roughly 2 trillion galaxies in the observable universe.
The International Space Station is the largest man-made object in space.
Spacecraft have visited all known planets in our solar system.

Introduction

Space, the final frontier, has captivated human imagination and scientific inquiry for centuries. From ancient astronomers to modern astrophysicists, the quest to understand the cosmos has driven countless explorations and discoveries.

The Planets

Mercury

Mercury, the smallest planet in our solar system, completes an orbit around the Sun in just 88 Earth days. Due to its proximity to the Sun, Mercury’s surface temperatures can soar to a scorching 427°C during the day, while at night, they can plummet to a frigid -173°C. Despite its extreme temperatures, Mercury has a surprisingly thin atmosphere composed of oxygen, sodium, and hydrogen. The planet’s surface is heavily cratered, resembling our Moon, and it lacks any moons of its own.

Venus

Venus, often referred to as Earth’s twin because of its similar size and mass, is an enigma. Its thick, toxic atmosphere is composed mostly of carbon dioxide, with clouds of sulfuric acid, creating a runaway greenhouse effect. This makes Venus the hottest planet in our solar system, with surface temperatures reaching 467°C. The planet rotates on its axis very slowly and in the opposite direction of most planets, causing its day to be longer than its year.

Earth

Earth, our home, is unique in its ability to support life. It has a diverse climate system, abundant liquid water, and a protective atmosphere composed mainly of nitrogen and oxygen. Earth’s magnetic field and atmosphere shield it from harmful solar and cosmic radiation, making it a hospitable environment for a wide variety of life forms. Earth has one natural satellite, the Moon, which has a significant impact on the planet’s tides and stabilizes its axial tilt.

Mars

Mars, the fourth planet from the Sun, has long fascinated humanity. Known as the Red Planet due to its iron oxide-rich soil, Mars has the largest volcano in the solar system, Olympus Mons, and the deepest canyon, Valles Marineris. Mars’ thin atmosphere, composed mostly of carbon dioxide, cannot retain heat, resulting in temperature extremes from -125°C at the poles to 20°C at the equator. Recent missions have found evidence of liquid water in the past, raising the possibility of ancient life.

Jupiter

Jupiter, the largest planet in our solar system, is a behemoth composed primarily of hydrogen and helium. Its massive size means it has a strong magnetic field and dozens of moons, including the four largest—Io, Europa, Ganymede, and Callisto—discovered by Galileo Galilei. Jupiter’s atmosphere is marked by colorful bands and the Great Red Spot, a gigantic storm that has raged for centuries.

Saturn

Saturn, the sixth planet from the Sun, is renowned for its spectacular ring system, composed of ice and rock particles. Like Jupiter, Saturn is a gas giant made mostly of hydrogen and helium. It has 83 moons, with Titan being the largest. Titan has a thick atmosphere and lakes of liquid methane and ethane, making it a fascinating object of study for scientists exploring the potential for life in extreme conditions.

Uranus

Uranus is an ice giant with a unique feature—its axis is tilted at an angle of about 98 degrees, causing it to rotate on its side. This unusual tilt results in extreme seasonal variations. Uranus’ atmosphere contains hydrogen, helium, and methane, which gives the planet its characteristic blue-green color. It has 27 known moons, with Miranda and Titania being the most notable for their extreme geological features.

Neptune

Neptune, the farthest planet from the Sun, is known for its dynamic atmosphere and incredibly strong winds, the fastest in the solar system. Like Uranus, Neptune is an ice giant with a bluish appearance due to methane in its atmosphere. It has 14 known moons, with Triton being the largest. Triton is geologically active, with geysers that spew nitrogen gas, and it has a retrograde orbit, suggesting it was captured by Neptune’s gravity.

The Solar System

The Asteroid Belt

The asteroid belt, situated between Mars and Jupiter, is a region filled with millions of rocky bodies. These asteroids vary in size from tiny pebbles to Ceres, the largest object in the belt, which is also classified as a dwarf planet. The asteroid belt represents remnants from the early solar system that never coalesced into a planet, providing scientists with valuable insights into the solar system’s formation.

The Kuiper Belt

The Kuiper Belt extends beyond Neptune’s orbit and is populated with icy bodies and dwarf planets, including Pluto. This region is similar to the asteroid belt but is much larger and contains objects composed mainly of frozen volatiles like methane, ammonia, and water. The Kuiper Belt is the source of many short-period comets that occasionally become visible from Earth.

The Oort Cloud

The Oort Cloud is a theoretical distant cloud of icy bodies that surrounds the solar system. It is believed to be the source of long-period comets that take thousands of years to complete an orbit around the Sun. The Oort Cloud marks the boundary of the Sun’s gravitational influence and the beginning of interstellar space.

The Sun

The Sun, a G-type main-sequence star, is the central and most massive object in our solar system. It provides the energy necessary for life on Earth through the process of nuclear fusion, where hydrogen atoms are fused into helium, releasing immense amounts of energy. The Sun’s surface, or photosphere, has a temperature of about 5,500°C, while its core can reach temperatures of 15 million°C.

Solar Eclipses

Solar eclipses occur when the Moon passes between the Earth and the Sun, casting a shadow on Earth. There are three types of solar eclipses: total, partial, and annular. A total eclipse, where the Sun is completely obscured by the Moon, is a rare and awe-inspiring event. An annular eclipse occurs when the Moon is too far from Earth to completely cover the Sun, creating a ring-like appearance.

Comets, Asteroids, Meteorites, and Meteor Showers

Comets

Comets are icy bodies that originate from the Kuiper Belt or Oort Cloud. As they approach the Sun, their ices vaporize, creating a glowing coma and a tail that can stretch millions of kilometers. Comets have highly elliptical orbits, bringing them close to the Sun before they swing back into the outer solar system. Famous comets include Halley’s Comet, which returns to the inner solar system every 76 years.

Asteroids

Asteroids are rocky objects that orbit the Sun, primarily found in the asteroid belt. They vary greatly in size, and some have even been classified as dwarf planets. Asteroids can provide valuable information about the early solar system, and some, like Ceres, have shown signs of water, suggesting they could harbor conditions favorable for life.

Meteorites

Meteorites are fragments of asteroids or comets that survive their passage through Earth’s atmosphere and land on the surface. They are classified into three main types: stony, iron, and stony-iron meteorites. Studying meteorites allows scientists to gain insights into the composition and history of the solar system.

Meteor Showers

Meteor showers occur when Earth passes through the debris trail left by a comet. As these small particles enter Earth’s atmosphere, they burn up, creating bright streaks of light in the sky. Some of the most well-known meteor showers include the Perseids, which peak in August, and the Geminids, which occur in December.

Comet passing in front of planet earth (3D uv map from http://visibleearth.nasa.gov)

Moons

The Moon: Earth’s Companion

Earth’s Moon is the fifth-largest moon in the solar system and has a significant impact on our planet. It influences ocean tides, stabilizes Earth’s axial tilt, and has been a source of inspiration and study for millennia. The Moon’s surface is marked by impact craters, maria (large basaltic plains), and mountains. The Apollo missions of the 1960s and 1970s brought humans to the Moon, providing a wealth of scientific data and samples.

Mars’ Moons: Phobos and Deimos

Mars has two small moons, Phobos and Deimos, thought to be captured asteroids from the asteroid belt. Phobos orbits very close to Mars and is slowly spiraling inward, while Deimos orbits further away. Phobos, with its irregular shape and surface covered in grooves and craters, is gradually getting closer to Mars and may eventually crash into the planet or break apart.

The Galilean Moons: Jupiter’s Largest Satellites

Jupiter’s four largest moons—Io, Europa, Ganymede, and Callisto—were discovered by Galileo Galilei in 1610. Io is the most volcanically active body in the solar system, while Europa is believed to have a subsurface ocean that may harbor life. Ganymede, the largest moon in the solar system, has its magnetic field, and Callisto’s heavily cratered surface hints at a long and complex history.

Saturn’s Moons

Saturn’s moons include Titan, Enceladus, and many others. Titan, the largest, has a thick atmosphere and lakes of liquid methane and ethane, making it a target for future exploration. Enceladus, with its geysers that eject water ice and organic molecules, has drawn interest due to the potential for life in its subsurface ocean.

Uranus and Neptune’s Moons

Uranus’ moons, like Miranda and Titania, are known for their extreme geological features, such as cliffs and valleys. Neptune’s moon Triton has geysers that spew nitrogen gas and a retrograde orbit, indicating it was likely captured by Neptune’s gravity.

Dwarf Planets

Ceres: The Largest Asteroid

Ceres, located in the asteroid belt, is the only dwarf planet in the inner solar system. It has a differentiated interior with a rocky core and an icy mantle. Observations from the Dawn spacecraft revealed bright spots on its surface, believed to be deposits of sodium carbonate.

Pluto: A Dwarf Planet with a Heart

Pluto, once considered the ninth planet, is now classified as a dwarf planet. It has five known moons, with Charon being the largest. Pluto’s surface features mountains, valleys, plains, and craters, and the New Horizons mission provided stunning images and data about this distant world.

Haumea, Makemake, and Eris: Remote Worlds

These distant dwarf planets, located in the Kuiper Belt, have unique characteristics. Haumea has a rapid rotation and an elongated shape, Makemake is known for its lack of atmosphere, and Eris is one of the most massive dwarf planets, even more massive than Pluto.

Galaxies

The Milky Way: Our Galactic Home

The Milky Way is a barred spiral galaxy containing our solar system. It has a diameter of about 100,000 light-years and is home to approximately 100-400 billion stars. Our solar system is located in one of the spiral arms, about 27,000 light-years from the galactic center.

Andromeda: The Nearest Spiral Galaxy

The Andromeda Galaxy, the nearest spiral galaxy to the Milky Way, is on a collision course with our galaxy. This merger is expected to occur in about 4.5 billion years, resulting in a new galaxy often referred to as “Milkomeda.”

Other Notable Galaxies

Sombrero Galaxy: Known for its bright nucleus and large central bulge, resembling a sombrero hat.
Whirlpool Galaxy: Famous for its well-defined spiral arms and interaction with a companion galaxy.
Triangulum Galaxy: The third-largest galaxy in the Local Group, it is a face-on spiral galaxy.
Magellanic Clouds: Two irregular dwarf galaxies orbiting the Milky Way, visible from the Southern Hemisphere.
Pinwheel Galaxy: A face-on spiral galaxy in the constellation Ursa Major, known for its symmetrical structure.
Messier 87: A giant elliptical galaxy with a supermassive black hole at its center, famous for its jet of energetic particles.
Antennae Galaxies: A pair of interacting galaxies in the process of merging, creating a spectacular array of star-forming regions.

What is Outer Space?

Outer space is the vast expanse beyond Earth’s atmosphere. It is a near-perfect vacuum, devoid of air and with extremely low pressure and temperatures. Despite its emptiness, space is teeming with activity, from the movement of galaxies to the formation of stars and planets.

Interesting Facts about Space

No definitive boundary: Space does not begin at a specific altitude above Earth, but the Kármán line at 100 km is a commonly used definition.
Extremely cold temperatures: The temperature in the void of space is about −270.45 °C.
Hard vacuum: Space is a void containing very little matter.
No sound: There is no sound in space because molecules are too far apart to transmit sound.
Sparse matter: The space between galaxies is not completely empty but has an average of one atom per cubic meter.
Numerous stars: There are an estimated 100-400 billion stars in our galaxy, the Milky Way.
Old and expanding universe: The universe is observed to be 13.8 billion years old and has been expanding since its formation in the Big Bang.
Countless galaxies: In the observable universe, there are an estimated 2 trillion galaxies.
International Space Station: The largest ever crewed object in space.
Planetary exploration: Spacecraft have visited all the known planets in our solar system.

Tables

Table 1: Characteristics of the Planets

Planet	Distance from Sun (AU)	Diameter (km)	Atmosphere Composition	Average Temperature (°C)
Mercury	0.39	4,880	Oxygen, Sodium, Hydrogen	-173 to 427
Venus	0.72	12,104	Carbon Dioxide, Nitrogen	467
Earth	1.00	12,742	Nitrogen, Oxygen	15
Mars	1.52	6,779	Carbon Dioxide, Argon	-125 to 20
Jupiter	5.20	139,820	Hydrogen, Helium	-145
Saturn	9.58	116,460	Hydrogen, Helium	-178
Uranus	19.22	50,724	Hydrogen, Helium, Methane	-224
Neptune	30.05	49,244	Hydrogen, Helium, Methane	-214

Table 2: Notable Moons in the Solar System

Moon	Planet	Diameter (km)	Notable Features
Moon	Earth	3,474	Influences tides, stabilizes Earth’s tilt
Phobos	Mars	22.4	Gradually getting closer to Mars
Deimos	Mars	12.4	Smaller and more distant than Phobos
Io	Jupiter	3,643	Most volcanically active body in the solar system
Europa	Jupiter	3,121	Possible subsurface ocean
Ganymede	Jupiter	5,268	Largest moon in the solar system
Callisto	Jupiter	4,821	Heavily cratered surface
Titan	Saturn	5,151	Thick atmosphere, liquid methane lakes
Enceladus	Saturn	504	Geysers ejecting water ice
Triton	Neptune	2,707	Retrograde orbit, geologically active

Conclusion

The exploration and study of space continue to expand our understanding of the universe and our place within it. From the planets in our solar system to the countless galaxies beyond, space holds endless mysteries and opportunities for discovery. As our technology and knowledge advance, so too will our ability to explore and understand the vast cosmos that surrounds us. The journey of space exploration is far from over, promising new adventures and revelations in the years to come.

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#SpaceFacts, #Astronomy, #Planets, #SolarSystem, #Galaxies, #Cosmos, #SpaceExploration, #Universe, #Asteroids, #Comets

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Earth Observation Satellites

Hubble Accidentally Finds More Than a Thousand Asteroids

By Jonathan Bala April 24, 2024

Hubble Accidentally Finds More Than a Thousand Asteroids

Key Takeaway

Hubble Space Telescope’s archival data, combined with citizen science and machine learning, has uncovered over a thousand previously unknown asteroids, shedding light on the formation of our solar system.

Summary

An international team of citizen scientists, astronomers from ESA, NASA, and universities, along with machine learning algorithms, analyzed archival data from the Hubble Space Telescope.
They discovered over 1,000 previously uncatalogued asteroids, with around 400 being smaller than 1 km in size.
Asteroids leave curved trails in Hubble’s images due to their motion relative to Hubble’s changing position as it orbits Earth.
Studying the orbits and properties of these asteroids can help test theories about the formation and evolution of the main asteroid belt.
One theory suggests small asteroids are fragments of larger ones that have collided and ground down over billions of years.
Another theory proposes small asteroids formed as they appear today and have not changed much since the formation of the Solar System.
The study provides insights into the largely unseen population of very small asteroids in the main belt.
This citizen science approach, combined with machine learning, can be applied to datasets from other asteroid-hunting observatories like Spitzer, SOFIA, and potentially the James Webb Space Telescope in the future.
The team plans to further characterize the orbits, rotation periods, and other properties of these newly discovered asteroids.

Hubble Accidentally Finds More Than a Thousand Asteroids — This graph uses data from the Hubble Space Telescope archives. It was created to show a population of very small asteroids that are mostly unseen.

Hubble’s Accidental Asteroid Discoveries

The Hubble Space Telescope has once again proven its worth as a scientific powerhouse, even after more than three decades in operation. In a remarkable feat, an international team of citizen scientists, astronomers from ESA, NASA, and other institutions, along with the aid of machine learning algorithms, has uncovered over a thousand previously unknown asteroids hiding in Hubble’s archival data.

Hubble was meant to study far-off galaxies and cosmic objects. But, it accidentally also took pictures of asteroids. These asteroids appeared as curved trails in Hubble’s images because they were moving around the Sun. They unexpectedly appeared in the telescope’s view. This gave astronomers a chance to learn about the Main Asteroid Belt. This belt is an area with many asteroids, located between Mars and Jupiter.

Among the newly discovered asteroids, a significant number – around 400 – measure less than 1 kilometer in size. This remarkable dataset offers an invaluable glimpse into the formation and evolution of our solar system. Two competing theories have long been debated by astronomers: did these small asteroids form as they appear today billions of years ago, or are they fragments of larger asteroids that have been colliding and grinding each other down over eons?

The data collected from Hubble’s accidental asteroid discoveries could help shed light on this enigma, providing crucial insights into the processes that shaped the early solar system.

This project succeeds due to great teamwork between volunteers and advanced machine learning. The Hubble Asteroid Hunter project started in 2019. It attracted more than 11,000 volunteers. These volunteers carefully reviewed 37,000 Hubble images from almost 20 years. Their hard work offered the data needed for machine learning algorithms. These algorithms can now spot asteroid trails very accurately. This new method has revealed hidden asteroids in Hubble’s archives. It also opens doors for more discoveries in astronomy.

This study introduces new breakthrough methods in finding and analyzing asteroids. It combines citizen science with machine learning. This allows astronomers to examine large amounts of data. They look at data from observatories like NASA’s Spitzer Space Telescope and the Stratospheric Observatory for Infrared Astronomy (SOFIA). They might also use data from the James Webb Space Telescope.

As the next step, the research team plans to analyze the orbits, rotation periods, and other properties of the newly discovered asteroids, further expanding our understanding of these enigmatic celestial bodies.

Hubble’s accidental asteroid discoveries serve as a testament to the enduring scientific value of the telescope and the ingenuity of researchers in extracting every bit of knowledge from its data. By harnessing the collective power of citizen scientists and cutting-edge technology, astronomers have unlocked a treasure trove of information that will undoubtedly shape our comprehension of the solar system’s origins and evolution.

As Hubble travels through space, we can look forward to unexpected discoveries and major breakthroughs. These will strengthen its reputation as one of our era’s most important scientific tools.

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#HubbleSpaceTelescope, #Asteroids, #CitizenScience, #MachineLearning, #SolarSystem, #SpaceExploration, #Astronomy, #AsteroidBelt, #DataScience, #ScientificDiscoveries

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