Space Weather

Posted on March 12, 2019 by alexdickey18

In this post, we will be discussing space weather! Space weather is dissimilar from the weather that we experience on earth, however it is still fascinating to understand. Space weather, in our solar system, is sparked by activity on the suns surface. Spewing gases and solar flares on the surface of the sun form into a stream of particles that we call solar wind. Solar wind carries all of these particles toward earth and the rest of our solar system at up to a million miles per hour. Luckily, due to earths atmosphere, these particles do not enter our atmosphere and we are protected from the harsh solar wind that the sun gives off. Shown in the image below, the atmosphere surrounding earth serves as a shield which deflects this wind.

An illustration showing the Sun's solar wind as orange flares blowing toward Earth and shaping Earth's magnetic field as blue lines
Image of solar wind deflecting on earths atmosphere, retrieved from NASA

Although incredibly deadly and harsh, sometimes these charged particles are able to sneak into our atmosphere and create something beautiful. This beauty is non other than the auroras that some people can only dream of witnessing.

A photograph of green aurora against a dark night sky
An Aurora as seen in Alaska, retrieved from NASA

Devastating to a world without an atmosphere, space weather is a fascinating side effect of a constantly volatile and hot space object similar to our sun. Luckily, we are born on a world with a natural defense and if any of these particles manage to pass through, a marvelous spectacle is waiting to happen.

Posted in Class, Sun | Tagged , , , , , | Comments Off on Space Weather

Terraforming Mars: Chances are as Thin as the Air

Posted on March 12, 2019 by IanO12
A potential view of an Earth-like Mars. Greg Fish, World of Weird Things.

Many of the futurists and sci-fi enthusiasts of today will at some point think about trying to live on Mars. However, terraforming the planet seems increasingly difficult as we learn more about the process. The first step, and a limiting one, is Mars’ atmosphere. This NBC article summarizes the findings of a 2018 study concerning the very idea. Essentially, Mars does not have enough carbon dioxide to significantly warm the planet via the greenhouse effect, at least by using current technology. This is not a unanimous conclusion: Elon Musk, in all of his spectacle, suggested we should blow up the ice caps on Mars with nuclear warheads to release the needed gas into the atmosphere. Despite the efficacy or success of this, I still have my concerns. Mainly, how can we be sure the atmosphere would not get stripped away anyway? A nuke would likely make things pretty hot, possibly allowing some air to reach escape velocity. In addition, Mars has no magnetosphere. And without that electromagnetic flow around the planet, the atmosphere is susceptible to solar winds anyway. It’s not looking great for the Red planet to go green.

Posted in Class | Tagged , , , , | Comments Off on Terraforming Mars: Chances are as Thin as the Air

Atmospheres of Terrestrial Worlds

Posted on March 12, 2019 by alexdickey18

In this blog we will be discussing the atmospheres of terrestrial worlds; more specifically what an atmosphere really is and the difference in atmospheres between different worlds. An atmosphere is simply a “layer of gas that surrounds a world.” In general, this relatively thin layer of gas is responsible for blocking the suns rays and trapping heat within a world. In the example of earth, the atmosphere is essential to our survival. Earth’s atmosphere creates a pressure barrier that allows for water to exist in all three states, oxygen to exist within our globe without escape, and maintain a temperature that is suitable for living. Below is an image that shows what earths atmosphere looks like from space.

Earth’s atmosphere from space

So, how does our atmosphere differ from other worlds within our very own solar system?

Mercury and our moon are similar in that their atmosphere is SO insignificant that they are often thought to not have one. This means that the suns harsh rays come in immediate contact with the surface as they are not scattered by a layer of gas. This also means that when standing on the surface of these worlds, the sky will be pitch black as opposed to Earth.

Venus, on the other hand, has a thick atmosphere. This makes it so that the sky is always cloudy and gloomy and the heat that is created as a result of volcanic activity is there to stay.

Posted in Class | Tagged , , | Comments Off on Atmospheres of Terrestrial Worlds

The Mysterious Black Hole

Posted on March 12, 2019 by Yihao Yan
A simulation of a black hole, picture from popsci

The black hole is one of the most amazing and mysterious object in our universe. In 1916, Karl Schwarzschild first provided the solution to general relativity that characterize a black hole.

Black hole is the remnant of super massive star’s explosion, and it has such a strong gravitational pull that nothing can escape, not even particles and light (electromagnetic radiation). And this is why it gets the name “black hole”.

The model of black hole is supported by the theory of general relativity that a super massive object can deform the space-time to form a black hole and the boundary that nothing can escape is called event horizon. The movie “Interstellar” has a very famous part about the horizon event and falling into blackhole.

View of black hole in “Interstellar”, picture from YouTube

The black hole has three independent properties: mass, charge and angular momentum. The center of black hole, according to general relativity, is the singularity where the curvature of space-time is infinite.

Another interesting thing about black hole is called gravitational time dilation. It’s describing that if something is falling into black hole, as it’s closer to event horizon, the time will be slower according to general relativity. And it will take infinite amount of time to reach event horizon.

On February 11th 2016, LIGO announced the first detection of gravitational waves, which also represent the first observation of black hole merging.

Posted in Physics, Universe | Tagged , , , | Comments Off on The Mysterious Black Hole

The Militarization of Space: What We Know Might Scare You. What We Don’t Know is Probably Even Worse.

Posted on March 12, 2019 by jpeilbert
ASAT_missile_launch
A high-altitude anti-satellite missile launch. Source: Paul E. Reynolds at Wikipedia Commons

What do you think was the first man-made object in space? Who do you think launched that object?

It may surprise you to find out that the first man-made object to reach space was a V-2 rocket launched by Nazi Germany in 1944. Fortunately, the Third Reich was defeated before their successes in rocketry could be exploited further than the V-2. It should come as no surprise that the United States and Soviet Union took up this mantle, developing a fearsome array of real and theoretical space-based weapons.

The 1967 Outer Space Treaty banned the testing or storage of nuclear weapons above Earth’s atmosphere. Unfortunately, it’s rather difficult to enforce this ban: space is big, and it would be relatively easy to hide a nuclear launch platform up there. At least those of us who trust the honesty of nuclear-capable nations can feel safe believing that there are not nuclear weapons stationed above our heads, ready to drop at any moment.

Non-nuclear space weapons definitely exist, however:

The Soviets launched their Almaz military space stations in the 1970s, equipping them with rapid-fire externally-mounted cannons to repel enemy spacecraft.

Anti-satellite (ASAT) weapons have been tested by several nations and been proven successful in destroying targets in orbit.

The Reagan administration proposed the Strategic Defense Initiative (aka ‘Star Wars’), which hoped to deploy space-based lasers to shoot down incoming Soviet missiles before they could reach the US.

One of the scariest possibilities is kinetic bombardment, also known as “Rods from God”. Rods from God are heavy, dense slugs which can be stationed in space, ready to be de-orbited at any time. On the ground, this de-orbiting means an unbelievably large, entirely unpredictable release of kinetic energy anywhere on Earth.

From the V-2 to Rods from God, military space technology can be absolutely terrifying. With a budget comparable to (or perhaps far greater than, it’s classified) that of NASA, the US military space program is certainly capable of implementing some of the most devastating space-based weapons imaginable. And it’s only a small consolation that much of that budget probably goes towards spy satellites.

Posted in Class | Tagged , , | Comments Off on The Militarization of Space: What We Know Might Scare You. What We Don’t Know is Probably Even Worse.

The Sun

Posted on March 12, 2019 by calebglotta
The Suns Layers

Everyone knows the sun is what gives us light, much of our heat, and is vital to life on Earth, however there are many intriguing aspects that people do not know. The sun was formed four and a half billion years ago from the gas of a collapsing space cloud. This cloud continued to contract until the core was able to sustain nuclear fusion, which maintains energy balance between the energy being released into space from the suns surface and the core. The sun is roughly halfway through its ten-billion year lifetime, after which the suns “fuel” will run out and gravitational contraction will resume. The sun’s structure from inside out is the core, radiation zone, convection zone. Then, its atmosphere is made up of the photoshpere, chromoshpere, and the corona (the outer most layer of the sun’s atmosphere). In the sun’s core the temperature reaches around 15 million kelvin and the pressure is 200 billion times that on earth’s surface. In the next layer up, radiation zone, the temperature cools to around 10 million kelvin. Here, energy moves out in the form of photons. After this layer their is the convection zone, here the the cooler gas from the surface falls and the hotter gas rises. The sun is quite incredible in many ways and the extremes of the suns size, temperature, and gravity make it difficult to really comprehend.

Posted in Class, Sun | Tagged , , | Comments Off on The Sun

Interplanetary Rocket Travel and the Rocket Equation

Posted on March 12, 2019 by Andrew Talley

In rocket travel, one of the most essential elements is ∆v – the change in a ship’s velocity. The spaceship needs to accelerate to get out of the atmosphere, and then speed up to achieve orbit. If it’s going to another planet, it needs to achieve escape velocity from Earth, then speed up/slow down its orbit around the Sun to become intercepted by that other planet.

One of the most famous equations that governs this is (aptly) called the “rocket equation“: \Delta v = v_e ln\frac{m_0}{m_f} . This is complicated, so let’s break down each variable.

\Delta v in this equation is what we discussed above – the change in velocity.

v_e is the “effective exhaust velocity” – for our purposes, it just matters that this depends on the engine design. We’ll use SpaceX’s Raptor Engine, which has a “specific impulse” (or I_{sp} ) of 380s in a vacuum. You can get v_e by multiplying I_{sp} by the gravity at the Earth’s surface, which gives us v_e (Raptor Engine) = 380s \cdot 9.8m/s^2 = 3724m/s .

m_0 is the initial mass of the rocket, and m_f is the final mass of the rocket (after earlier stages have been discarded and fuel burned). The important thing to notice about these is they are within the logarithm ln\frac{m_0}{m_f} . That matters, because it means that as you want \Delta v to increase, the ratio \frac{m_0}{m_f} has to increase exponentially.

To give a bit of intuition for why that is: imagine you start with a probe. To get it to move, you only need a somewhat small engine – say we have a rocket with the same mass as the probe, and that gets us some acceleration. If we want it to go further, we need a rocket powerful enough to power both the probe and the engine we were using it before. So to get that same acceleration, we need to double the mass of the whole rocket again, leaving us with a new rocket four times as large. To get the same acceleration again, the rocket needs to be eight times as large. There’s the exponential climb.

Here’s a graph showing that exponential decline in more precision:

Source: Wikipedia

The interesting thing about this equation is that m_0 and m_f are the main things we control. Orbital mechanics gives us a required \Delta v if we want to orbit Earth, or go to Mars, or leave the solar system. The only thing we control is: how big is the probe we’re sending, and how big is the rocket we’re sending it on. So if we want to go to one of these places, we can find out exactly what percent of the mass of our first rocket we could theoretically keep. That’s what I calculated.

Below is the result of all of this. For each other world in our solar system, what percent of our mass can we keep? If we want to send 1 ton of stuff (cameras, sensors, food, people, etc.) to that world, how big of a rocket do we need?

WorldRequired ∆v% of Mass to Worldm_0 for m_f = 1t
Moon15.93 km/s1.392%72 tons
Mars21.3 km/s0.329%304 tons
Venus21.2 km/s0.338%296 tons
Mercury23.3 km/s0.193%519 tons
Juptier24 km/s0.160%627 tons
Saturn25 km/s0.122%819 tons
Neptune26 km/s0.093%1072 tons
Pluto26 km/s0.093%1072 tons
Escape Sun26.5 km/s0.082%1226 tons

Again, all of this assumes that we only use Raptor Engines to power our rocket, it ignores the different specific impulse in the atmosphere, and (most importantly) this is only enough to send your ship crashing into the other planet – not into orbit, and certainly not to land on it gently. All of those only take up more delta-v, which means you need a bigger rocket to start with.

Posted in Physics, Space Travel | Tagged , | Comments Off on Interplanetary Rocket Travel and the Rocket Equation

Blog 4: Humans back on the Moon and on to Mars

Posted on March 12, 2019 by Katie

NASA’s plans for sending people to Mars are intertwined with their plans to send humans to the Moon more consistently, and hopefully to be able to establish a human presence their within the decade. They plan to launch the Gateway, a spaceship that will orbit the moon to support future trips there. They plan to launch it in 2022. By having people live on the spaceship they can better understand “how the human body responds in a true deep space environment before committing to the years-long journey to Mars”.

NASA’s Spaceship Design

SpaceX wants to establish a Mars base in the 2020s and plans to launch cargo flights by 2022. This seems a little ambitious to me, though granted I don’t know how long this has been in the works; however, I’d imagine it takes a very long time to design, plan, launch, and travel to Mars especially given NASA’s timeline and the 34-million-mile distance to Mars.

Posted in Space Travel | Tagged , , , | Comments Off on Blog 4: Humans back on the Moon and on to Mars

The Atmosphere of Venus

Posted on March 12, 2019 by luanaisaac1125
A true-color image of Venus.
Author/Source: NASA via Wikipedia

Venus’s atmosphere is very, very dense. It is composed of about 96% carbon dioxide, 3.5% nitrogen, and trace amounts of other gases, including sulfur dioxide. Although Earth’s atmosphere is composed of over 75% nitrogen, Venus’s atmosphere is so dense that the 3.5% of its atmosphere that is composed of nitrogen has around 4 times the mass of the nitrogen found in Earth’s atmosphere. The density of the atmosphere on Venus also means that there is about 90 times the atmospheric pressure on Venus’s surface than on Earth’s, which is pressure similar to what would be experienced if you dove about 1000 meters under the surface of one of Earth’s oceans.

The composition of Venus’s atmosphere is also largely responsible for its surface/planetary heat. In the past, the increasing brightness of the early sun, as well as the composition of Venus’s atmosphere (carbon dioxide is a greenhouse gas, which warms the planet), contributed to a runaway greenhouse effect. This effect is essentially a positive feedback loop that caused the planet’s ocean(s) to evaporate and the surface temperature to rise higher and higher. Because of this, Venus’s surface is even hotter than Mercury’s, despite the fact that Mercury is closer to the Sun. The carbon dioxide, sulfur dioxide, and trace amounts of water vapor in Venus’s atmosphere also react with each other to form clouds made up of sulfuric acid, a corrosive compound that can result in severe burns and skin tissue damage; however, acid rain never reaches the surface of Venus since the intense heat evaporates it all before it can reach the surface.

Posted in Class | Tagged , , , , | Comments Off on The Atmosphere of Venus

Understanding Our Sun

Posted on March 12, 2019 by dayvon

On August 12, 2018 the Parker Solar Probe was launched. The mission of this probe is to investigate activity in the Sun’s corona in order to provide us with information that can help us understand more about the star and Earth’s connection to it. Analyzing the data being sent back will allow scientists to potentially forecast different space-weather events, in addition to studying what makes the corona hotter than the surface, and the effects this has on Earth and the other planets of our Solar System.

Source: NASA – Parker Solar Probe Concept of Operations

The spacecraft will travel closer to the Sun than any other spacecraft ever has, and it was made to tolerate the extreme conditions, such as heat and radiation, that it will face during its journey. The probe has already completed its first orbit as of January 19, 2019, and is expected to orbit the Sun 23 more times. The data that has already been sent back has given scientists clues about things different phenomena that they would’ve never expected. Predictions are great, but it’s always better to get information straight from the source.


Source: NASA – Trajectory of the Parker Solar Probe

You can find more information about the probe and the mission here!

Posted in Sun | Tagged , , , | Comments Off on Understanding Our Sun