When Earth and the other planets were forming in the solar nebula around 4.5 billion years ago, not all of the material ended up inside of the planets and all of the moons. There were a lot of smaller pieces leftover; from itty, bitty microscopic stuff to pieces of rock and ice that can be many miles across. These are things like the asteroids and the comets in our solar system.
Throughout Earth’s history these pieces of rock and ice have continued to rain down from space to Earth’s surface. We often use the word “meteoroid” to describe these pieces of space stuff that can fall onto Earth. Once in our atmosphere, the piece of rock or ice will burn up and produce a streak of light. It’s that light that we call a “meteor” or a “shooting star”. Sometimes the chunks of material are so big that they even hit the ground. In that case, we call it a “meteorite”.
Meteorites of all shapes and sizes have impacted Earth. Investigations of the material in meteorites have shown that the chemical elements needed for life can be found inside of these space rocks. These elements are known as the CHNOPS elements (for carbon, hydrogen, nitrogen, oxygen, phosphorous, and sulfur). In fact, scientists who do research on meteorites have even found that many of the types of molecules made up of CHNOPS elements that are used by living things on Earth are inside of those space rocks as well. These molecules include things like sugars and amino acids. Amino acids are the building blocks of proteins for all living things. Not only have we found the basic building blocks of life in meteorites, but we’ve also now used spacecraft to show that we can find them on the surfaces of asteroids and comets. We’ve even detected molecules made up of the CHNOPS elements within the dust of the interstellar medium (the material that exists between the stars in our galaxy).
The molecules that include carbon are often referred to as “organic molecules”. These include a lot of the molecules made up of CHNOPS elements that are important for life. Sometimes when we talk about these organic molecules that can come to Earth from space, we call the “exogenous” materials. That means that they came from somewhere else (as compared to something that is “endogenous”). Our research has told us that the early solar system had a lot more rocks and ice orbiting about that could crash into Earth and other worlds. Just as today, those materials likely had a lot of exogenous organic molecules on and in them. So, in the early history of Earth, there were a lot more meteorites falling to Earth and bringing along these exogenous organic molecules. We don’t yet know if these meteorites were an important source of materials for Earth life, but it seems likely that they could have brought a lot of the CHNOPS elements to Earth for living things to later use.
So we know that the CHNOPS elements and even some of the basic building block molecules for life as we know it are actually quite common in the universe. Research on the connection between these materials from space and the presence of life on Earth will need to continue in order to better understand the history of life on Earth and to figure out if there could be other life somewhere out there.
Disciplinary Core Ideas
ESS1.C: The History of Planet Earth: Continental rocks, which can be older than 4 billion years, are generally much older than the rocks of the ocean floor, which are less than 200 million years old. (HS-ESS1-5) Although active geologic processes, such as plate tectonics and erosion, have destroyed or altered most of the very early rock record on Earth, other objects in the solar system, such as lunar rocks, asteroids, and meteorites, have changed little over billions of years. Studying these objects can provide information about Earth’s formation and early history. (HS-ESS1-6)
Scale, Proportion, and Quantity: The significance of a phenomenon is dependent on the scale, proportion, and quantity at which it occurs. (HS-LS2-1) * Using the concept of orders of magnitude allows one to understand how a model at one scale relates to a model at another scale. (HS-LS2-2)
Big Ideas: Material left over from the creation of the solar system sometimes enters Earth’s atmosphere adding material to the planet. When they fall from space, they can land on Earth, and then become a part of Earth. This mixes materials from space with the ingredients of life on Earth. Many bring the materials necessary for life, “CHNOPS”, with them frozen in ice.. Detection of CHNOPS from material beyond Earth indicates the building block molecules for life are common in the universe. Finding CHNOPS and amino acids beyond Earth helps with the search for life beyond Earth.
Boundaries: In this grade band, students use the periodic table as a model to predict the relative properties of elements. Examples of properties that could be predicted from patterns could include reactivity of metals, types of bonds formed, numbers of bonds formed, and reactions with oxygen. Focus is on main group elements. (HS-PS1-1)
3-12 A Guide to Collecting Micrometeorites. This lesson on identification and measurement of micrometeorites could be used as a rich hands-on investigation of the solar system origins, the formation of the Earth, the interaction of Earth and space and/or the delivery of the ingredients necessary for life (CHNOPS). ScienceSouth.org/NASA. http://www.sciencesouth.org/wp-content/uploads/2011/06/2016VF-A-Guide-to-Collecting-Micrometeorites-JMM-1.pdf
4-12 Finding Life beyond Earth, Activity 3: Basic Ingredients for Life (p. 19). Students make impact craters to gain insight into how comets and asteroids deliver water and chemicals to the Earth and other places in the solar system. https://d43fweuh3sg51.cloudfront.net/media/assets/wgbh/nvfl/nvfl_doc_collection/nvfl_doc_collection.pdf
5-12 Exploring Meteorite Mysteries: Building Blocks of Life (12.1). The team activities in this lesson explore the important materials carbonaceous chondrites brought to Earth. A jumbled letter activity leads students to look at the amino acids found in carbonaceous chondrites as the building blocks of life. Students also experiment with growing yeast in mediums that represent carbonaceous chondrite material. NASA. https://er.jsc.nasa.gov/seh/Exploring_Meteorite_Mysteries.pdf
5-12 Exploring Meteorite Mysteries: The Meteorite Asteroid Connection (4.1). This lesson allows students to understand how meteorites get from the asteroid belt to Earth and how rare it is for the Earth to be hit by a large asteroid. The students build an exact-scale model of the inner solar system; the scale allows the model to fit within a normal classroom and also allows the representation of Earth to be visible without magnification. Students chart where most asteroids are, compared to the Earth, and see that a few asteroids come close to the Earth. Students see that the solar system is mostly empty space unlike the way it appears on most charts and maps. NASA. https://er.jsc.nasa.gov/seh/Exploring_Meteorite_Mysteries.pdf
5-12 Exploring Meteorite Mysteries: Looking at Asteroids (5.1). This lesson is about the connection between meteorites and asteroids. The activities in this lesson focus on ways to look at asteroids because some scientists think that some meteorites are fragments of asteroids. The lesson centers on remote sensing techniques using light. Students consider the brightness (reflectivity), textures, and colors of materials. NASA. https://er.jsc.nasa.gov/seh/Exploring_Meteorite_Mysteries.pdf
6-12 Astrobiology Math. This collection of math problems provides an authentic glimpse of modern astrobiology science and engineering issues, often involving actual research data. Students explore concepts in astrobiology through calculations. Relevant topics include Death Stars (page 59) and A Mathematical Model of Water Loss from Comet Tempel-1 (page 55). NASA. https://www.nasa.gov/pdf/637832main_Astrobiology_Math.pdf