Month: March 2019

On Tuesday, March 19th, NASA is going to be hosting a media teleconference regarding the mission of a spacecraft collecting samples of the asteroid Bennu. This is one of the first spacecraft to ever complete such a mission, and is a very big deal in the space science community.

An image taken by OSIRIS-REx of the asteroid Bennu when it arrived in December, 2018.

The Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft was launched by NASA on September 8th, 2016, and travelled billions of kilometers from Earth for two years before orbiting the asteroid Bennu on December 31st, 2018. Since it’s arrival, NASA’s probe has been investigating the asteroid and searching for the perfect place for sample collection.

But it does beg the question, why is this mission such a big deal? Why Bennu?

The trip Bennu is one of the most ambitious attempted by a probe, as it will end up being a years-long endeavor. December marked the beginning of the two years that OSIRIS-REx will be investigating Bennu’s surface. It will brieftly touch the surface of Bennu around July of 2020 to collect between 60 and 2,000 grams of dirt and rocks (the largest sample gathered from a space object since the Apollo moon landings). After packing the sample into a capsule, OSIRIS-REx will begin the journey back to Earth and land in a Utah desert in 2023. Due to this, the mission is very important as observations of Bennu indicate that it could provide information on the formation of the solar system and the universe.

But Bennu is not only chosen because it is a leftover fragment of the tumultuous formation of our solar system. Yes, it is very old. The mineral fragments within this asteroid could be even older than our solar system, comprised of the dust of dying stars flung across space 4.6 billion years ago that eventually coalesced into everything we know today. However, it is also much closer than most asteroids. Most are between Mars and Jupiter, in the solar system’s asteroid belt. Bennu orbits between Earth and Mars on the same orbital plane, and comes closest to Earth every 6 years. In addition, this asteroid is the perfect size. It’s diameter is a little larger than the Empire State Building, which makes the asteroid approachable by probes and rich in regolith (unconsolidated rocky material covering bedrock, aka what NASA wants to collect parts of).

Bennu is also incredibly well preserved due to the vacuum of space, and may contain explanations to the origin of life on Earth. Scientists have been studying Bennu since it was discovered in 1999, and know that it is primarily carbon-constructed, so it could contain some clues into the eternal question of how life began on Earth since it has easily been around since then. Astronomers classify asteroids into one of three categories, with the most primitive being the carbon-rich ones that have most likely not changed in 4 billion years (like Bennu). Scientists are also interested in Bennu because it has a shifting orbit, and it is likely that it will collide with Earth in the late 22nd century.

Overall, monitoring the mission of OSIRIS-REx will be interesting over the next few years. Already the probe found hydrated minerals on the asteroid’s surface, indicating the presence of ancient water on the rocky surface of this space traveler. While we will not find out everything OSIRIS-REx discovers until September of 2023, it is definitely something to look forward to.

Sources:

https://www.nasa.gov/press-release/nasa-to-host-media-teleconference-on-asteroid-sample-return-mission

https://solarsystem.nasa.gov/news/517/why-bennu-10-reasons/

https://www.asteroidmission.org/why-bennu/

Ancient water found on asteroid Bennu

In all honesty, thinking about my last post about dark flow, I started to think more about the inflation theory of our universe being a bubble. We already know so little about our own universe, and the idea of cosmos beyond ours that we are unable to see is absolutely mind-boggling. The topic of dark flow, however, has now turned me to other “dark” things in our universe.

Most people have at least heard of “dark matter” and/or “dark energy”. It is mentioned in science fiction with typically insidious connotations, and for good reason.

When the Hubble Space Telescope observed a distant supernova in 1998, scientists had to alter their idea of universal expansion. They assumed that as more matter came into the universe, the pull of gravity would increase and the expansion of the universe would slow. However, after observing this Type 1a supernova (no hydrogen emissions and the brightest of all types of supernovae), it was clear that the universe is expanding at a more accelerated rate than it did hundreds of years ago. Astronomers came up with three possible reasons for this: it could be a result of a long-discarded version of Einstein’s theory of gravity that contained a “cosmological constant”; there could be some kind of strange energy-fluid that filled space; there could be something wrong with Einstein’s theory of gravity. While they do not know what the correct explanation is, they named the solution “dark energy”, which is the topic of this post.

For something that makes up 68-72% of the total mass-energy density of the universe (everything ever observed with all of our instruments, all normal matter, only makes up about 5%), and is responsible for the increased acceleration of our known universe, we know insanely little.

Einstein was the first to recognize that empty space was not nothing, and so many believe that dark energy is just a property of space. However, all energy is supposed to come from somewhere. The source is typically either matter or radiation, and so the notion presented is that space, even when devoid of matter and radiation, the universe has residual energy. It could also be a result of the strange actions of particles smaller than atoms (quantum mechanics). Quantum mechanics allows energy and matter to appear out of nothingness for only an instant, but this constant appearance and disappearance could be providing empty space with energy. But dark energy could also just be creating a new, fundamental force in the universe, which only starts to become observational when the universe reaches a certain size.

While more is unknown than known with regards to dark energy, we do know that since space is everywhere, so is dark energy. Its effects increase as space expands, as they go hand in hand. Its existence is only inferred through observations of gravitational interactions between astronomical interactions, and yet it is the reason for most major phenomenon with regards to universal expansion.

Dark energy, and its vast lack of knowledge on it, calls scientists towards an unexplored realm of physics. Dark energy could be evidence that outer space and the universe as a whole are configured vastly differently than we previously thought, and signal that we are on the brink of a new leap into understanding the universe.

 

Sources:

https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy

http://hubblesite.org/hubble_discoveries/dark_energy/de-what_is_dark_energy.php

http://astronomy.swin.edu.au/cosmos/D/Dark+Energy

http://astronomy.swin.edu.au/cosmos/T/Type+Ia+Supernova

Movement. It’s what powers the universe, as every aspect is constantly moving. Not only are planets orbiting stars, but stars rotate around galaxies that spin across the universe.

I hope you’re not motion-sick.

These clusters of massive galaxies that we are but insignificant specks in are constantly moving away from each other as the universe expands, which we know is occurring (according to the Big Bang Theory). Our observable universe, theoretically, is only 13.7 billion light years, as that is when the universe formed. By the theory of Hubble Flow, as the universe continues to expand beyond its’ current 13.7 billion light years in size, the expansion should be equal in all directions.

However, astrophysicists studying a CMB (Cosmic Microwave Background) Map – the remaining radiation from the Big Bang that invisibly coats the universe – discovered that patches of galaxies seem to be moving at high speeds towards a point beyond the perceivable universe. This has been referred to as “dark flow”.

Astronomers have been debating for years over whether or not dark flow is real, and if so, what the cause of it would be. Those that do not believe in it have solid reasoning. The distribution of matter in the universe does not account for it. But those who believe it is occurring are continuing to document and study this supposed phenomenon. There are multiple different theories about possible causes. One idea is that some mass that existed before cosmic inflation (when the universe expanded beyond its original compressed state) made such an immense impact on the matter of our universe that some galaxy clusters are still drawn to it.

Regardless of what causes it, many astronomers today do agree that studying CMB maps shows parts of giant clusters of galaxies moving approximately 2 million miles per hour towards a point between the constellations Centaurus and Hydra. While this would not be significant normally, they are moving in a direction that is separate and different from the direction of the expansion of the universe.

A separate theory of inflation of the universe posits that the universe we observe is only a small bubble of space-time that got rapidly expanded after the Big Bang, and that there could be other parts of outer space beyond our bubble that we are unable to see. In these regions beyond the bubble, space-time could be entirely different from how we experience it. In addition, it most likely would not have stars or galaxies, possibly containing supermassive structures that would be much larger than anything in our universe. Scientists who support this theory believe that these supermassive structures are the cause for dark flow, pulling galaxy clusters from outside our bubble.

A study on dark flow led by NASA’s Goddard Space Flight Center’s Alexander Kashlinsky, which includes researchers and equipment from universities around the world, has been occurring for a little over a decade. Since 2008, Atrio-Barandela, an associate and research colleague of Kashlinsky, has stated that the study has provided significant evidence to the existence of dark flow. The researchers are currently working to expand their catalog of galaxy clusters in order to track the dark flow to about twice the current distance.

This could be an interesting study to continue watching, as continued proof of dark flow may encourage other researchers to look into not only dark flow, but how the universe existed before inflation (the Big Bang) and what may exist beyond our bubble.

 

Sources:

https://www.popularmechanics.com/space/deep-space/a27635/dark-flow-space-time/

https://www.space.com/5878-mysterious-dark-flow-discovered-space.html

https://www.nasa.gov/centers/goddard/news/releases/2010/10-023.html