Monday, December 28, 2015

Falcon 9 & SpaceX

 From redditor tossha
The Falcon 9 is a two-stage rocket fully designed and manufactured by SpaceX.  It is, most importantly, partially reusable.  The first stage can land upright, autonomously.  This has been compared to balancing a rubber broomstick in a windstorm.   This is important because it means that all the cost of building a first stage can be recouped.  In addition, SpaceX's crew capsule (crew dragon) can be reused.

We'll get back to the design of the Falcon 9, but first, a bit of background.
Rocket technology has not significantly advanced since the '60s, so it still costs as much as ever to put stuff in space (US$13,812 per kilogram to low earth orbit for an Atlas V), which is why President George H. W. Bush's plan (announced in July 20, 1989) for a manned Mars mission was quickly thrown out when NASA told him that it would cost 500 billion US dollars.

SpaceX was started when Musk tried to create interest in space by sending a greenhouse to Mars, but everywhere he went for look for his rocket, he found it was ridiculously expensive.  So he started his own space exploration company.  He took the cost of the raw materials required to make a rocket, and compared them to the cost of a typical rocket price, and got about 2%.  The materials cost percentage of market price for a car is about 47%.  Elon Musk discovered that major aerospace firms don't want to fly unflown equipment, which means that no new technology ever gets used.  The way companies cut costs is by using engines actually manufactured in the '60s. 
So the Falcon 9 can launch a kilogram to low earth orbit for US$4109, because that SpaceX makes almost all of the rocket in-house, so there's none of the levels of sub-contractors that all want a piece of the price tag pie.  Plus, SpaceX uses modern methods of manufacturing and assembly that all cut costs.  And, of course, reusability will make it far cheaper than before, possibly 100 times cheaper.  Here Elon Musk sums it up nicely:
Imagine if you had to have a new plane for every flight. Very few people would fly. -Elon Musk
Airplanes aren't any cheaper to build if you reuse them, but you can make the price for a flight cheaper if you can do many flights with them.
But, I hear you ask, why is Elon Musk doing all this?  Considering that he was already rich from paypal, why did he decide to revolutionize space travel?  Because he wants (in addition to running a profitable company) to put 1,000,000 people on Mars.  And he wants their ticket to cost only 500,000 US dollars.  He wants to do this for two reasons, to create a "backup" of the human race, so if a mass extinction event happens to a planet with humans on it, the human race can survive, and for this reason:

This seems like a good idea, but we should be careful not to think of this as a solution for humans' impact on Earth.  Unsustainable fuels are unsustainable on Mars, and a terraformed Mars' ecosystem would be just as fragile as Earth's.  It is, however, a partial solution for overpopulation.  Ideally, it could open up far more space for humans.  Nonetheless, that space is not infinite.  Humans would have to continuously colonize new planets to support the growth of population.

Now, if you look almost all the way to the top of the post, you'll see that this was actually a digression.  Back to the Falcon 9!

The Falcon rocket family is named after the Millennium Falcon from the Star Wars franchise.  The first version of it was called the Falcon 1.  The Falcon 1 was designed to test construction techniques for the Falcon 1, while also launching satellites for profit.  SpaceX was at this being funded directly from Elon Musk's pocket, and it had money for 3 or 4 launches when it started.  The first launch was a failure.  So was the second and third.  Finally, on the fourth launch, the Falcon 1 made it into orbit, saving SpaceX from closing.  After that, NASA awarded a US$ 1.6 billion contract to SpaceX.

Then SpaceX built the Falcon 9.  Here we're going to be talking about the Falcon 9 v1.1 full thrust, the latest version.  The Falcon 9 has two stages, with 9 Merlin 1D engines on the first stage and one Merlin Vacuum 1D on the second stage.  First let's look at the Merlin engine:
The Merlin is developed fully in-house by SpaceX, and is the highest thrust to weight ratio (TWR) rocket ever built.  The 1D version has an absurd TWR of 165.9.  For comparison, the space shuttle main engine (SSME) gets only 73.1.  TWR is important in rocket engines because that the higher the TWR, the more mass the rocket engine can lift compared to it's mass, so you need less engine mass to lift the same amount of payload.  i.e., it's an incredible rocket engine.
Here's a Merlin 1D firing:

Now, the rocket:
The entire rocket uses many smart construction techniques, such as 3D printing to make their rockets cheaper.  Look at this first, for an idea of how it looks:
The first stage has one very important feature: reusability.  The first stage lands on four carbon fiber and aluminum honeycomb landing legs, which fold down for landing.
 From SpaceX 

 The first stage also has four deployable grid fins, at the top of the first stage, which help to keep the rocket on the right course.  The honeycomb structures in the photo below are the fins:
From SpaceX

In addition to these, there are small cold gas thrusters to keep the first stage on course during landing.

The second stage is like a small version on the first stage, with only one Merlin Vacuum 1D engine and a smaller tank.  It is not reusable.


Thursday, December 24, 2015

Where else to get space news

Here are the sources of news I get most of my space news from:
TMRO: The guys at TMRO make a new hour-long podcast every week, going over almost all space news for the week, and focusing on one aspect of spaceflight.
Spaceflight Now: This news site has articles on almost all space news.
Launch Library: Launch Library has a full list of all upcoming launches.
AmericaSpace: AmericaSpace has many spaceflight news articles, plus very nice On This Day articles.
Rocketology: This blog has a selection of interesting aspects of the development of the SLS.
Liquid Rocket Engines: While not being actively updated, this blog has many interesting posts about how rocket engines work.
Orion: The official NASA blog on Orion.
SpaceX: The official NASA SpaceX blog.

Wednesday, December 2, 2015

How to write a blog

  1. Get idea for post
  2. Procrastinate
  3. Make new draft, add title
  4. Procrastinate
  5. Feel creeping sense of dread because that you're afraid that your posts are getting farther and farther apart
  6. Do research
  7. Procrastinate
  8. Write entire post in 30 minutes
  9. Miss important section of post, fix
  10. Post looks to small, pad with images and videos
  11. Proof read *thunder and lightning*
  12. Exhaustedly add tags, publish
  13. Notice that every instance of they're, there, its and it's is completely wrong
  14. Swear that you'll finish the next post in a week, but first you'll take a well earned rest from blogging
  15. Procrastinate, and repeat

Thursday, November 26, 2015

Blue Origin's suborbital New Shepard booster makes a powered landing

The New Shepard vehicle is designed to launch a 6-person capsule into space, but not orbit, and then make a powered landing of the booster, so it can be reused.  The New Shepard is built by Blue Origin, a company which intends to sell flights into space to anyone.

Sunday, November 22, 2015

Mars and natural satellites

Mars is the fourth planet from the sun, and the second smallest planet after Mercury.  It's believed that in its past it could have harbored life, and may still, which seems more likely since the discovery of flowing water on Mars.

The house would probably fall victim to wild temperature swings (20 Celsius to -153 Celsius) or just be covered by dust.
Normal airplanes can't fly on Mars, because that it's atmospheric density is 100 times less than Earth's, and because that there isn't enough oxygen in the air to support combustion.  However, specially designed planes could fly on Mars.
There isn't enough liquid on Mars for a boat to float in.
The human is more interesting.  The atmosphere is mostly carbon dioxide, and extremely thin, and that, combined with the temperature changes, would make some kind of space suit necessary.  Food could possibly be farmed in a green house, or just carried along.  Water could be mined from the ground in places in the form of ice.  Rocket fuel could be refined in-situ.  A trip to Mars is much farther than a trip to the Moon, so it has to be much longer because of transfer windows, which only happens approximately every two years.  Plus, travel time:
This image shows why a faster trajectory is less efficient and requires more efficient engines:
You can read more about interplanetary trajectories here: 
And here's a handy spreadsheet:
Of course, all that time in zero-g causes muscle atrophy and osteoporosis, so many Mars mission proposals involve some kind of centrifuge, to create artificial gravity.

Finally, I want to add this: List of rocks on Mars.
Phobos and Deimos are the two moons of Mars.  It is believed that they are captured asteroids.  In most respects, they are like the Moon, except for gravity.  Deimos' escape velocity is 5.6 m/s, and Phobos' is 11.4 m/s, so it probably wouldn't be quite possible to reach escape velocity by running on Phobos, but maybe on Deimos.  With a bicycle, though, it probably would be possible.

Thursday, November 5, 2015

Alternate forms of rocket propulsion

There are other kinds of rocket engines than just chemical liquid fuel ones.  This post will quickly go over some of he other kinds of rocket engine.  Look at Wikipedia for a far more complete list of rocket engine types, but I'll go over the more common ones.

Solid-fuel rocket:
Solid fuel rockets are the oldest kind of rocket propulsion, invented in China in the 13th century.  Solid rockets use solid fuel and oxidizer instead of liquid fuels, which allows them to be stored easily for long periods of time.  However, they are less efficient, and cannot be turned off after ignition and before they run out of fuel.  These attributes make them popular for military applications because of their ability to be stored for long periods of time, and as booster rockets for the first stage of liquid rockets because of their low cost.

Hybrid rocket:
These are a mix of solid fuel rockets and liquid rockets.  In a hybrid rocket, one part of the fuel (either the fuel or the oxidizer) is in a solid form, similar to a solid rocket booster, except it cannot burn by itself.  The other part of the fuel/oxidizer mix is stored as a liquid in a pressurized tank attached at the bottom to the top of the solid part.  When the valve is opened from the tank, and the mix is ignited, the fuel and oxidizer burns.  Its advantages over solid rockets are mostly in safety, because that the engine can be quickly shut down.  Also, no turbomachinery is required.

Monopropellent rocket:
Monopropellent rockets use a single fuel by bringing it into contact with another chemical to produce a reaction which adds energy to the fuel.  Wikipedia has a good explanation of the different kinds of chemical reactions.  They are popular as reaction control system rockets, because of their simplicity and controllablity.  However, they have very low specific impulse, so they are poor primary engines.

Hypergolic rocket:
These work much like  normal liquid fuel rockets, except the fuels and oxidizers ignite on contact.  That's great for ease of storing, since no cryogenic tanks are necessary, but they are incredibly corrosive, toxic, and carcinogenic.  Even my spell-checker doesn't like them.  "Hyperbolic rockets?"

Nuclear thermal rocket (NTR):
In a nuclear thermal rocket, a fuel (probably hydrogen) is pumped around a nuclear reactor so it expands, and then expelled out the rocket nozzle.  It would have a specific impulse of about 850s, which is considerably higher than more conventional kinds of rocket engine.  It wouldn't be as powerful as a chemical engine (thrust-to-weight (TWR) ratio of 7:1 instead of 70:1) but it would excel in transfer stages where TWR is less important.  A lot of Mars mission proposals involve NTRs in some way, however, their development has been slowed since the cancellation of project rover, because of (very well-founded) environmental concerns over open air testing of nuclear rockets:
(A open air test of the Kiwi-A at Jackass flats, Nevada.)

Ion rocket:
These work by accelerating plasma (or ions) for use as a fuel.  They get extraordinarily high specific impulse, but at the cost of very low TWR, on some engines, equivalent to the weight of one sheet of paper constantly accelerating the spacecraft.  Honestly, I have no idea of the specifics of how they work, so take a look at Wikipedia for a detailed explanation.  However, I do know that they use a unusual fuel, such as xenon, and ionize it with electricity, propelling it outwards at 20-50 kilometers a second.

Of course, there are lots of kinds of more exotic rockets, some extremely theoretical, with names like Pulsed plasma jet, Fission sail, Nuclear pulse propulsion, reactionless drive, microwave powered rocket, Bussard ramjet.  Project Rho has a nice series of articles on these almost-sci-fi propulsion methods.

Tuesday, October 20, 2015

Earth and natural satellites

Today's planet is Earth.  Earth is the third planet from the sun, and at just the right distance to stay warm enough to have liquid water, but not so close to the sun to not have liquid water.  In other words, it has liquid water, which seems to be very important for life, which is why Mars is looking so interesting recently.  But I digress. 
The human, boat, plane and house would be fine on most of the Earth, since they were built for Earth.  But, let's say you wanted to make the Earth uninhabitable.  Or, better yet, non-existent.  Luckily for you, someone has made a list of plausible ways to destroy the Earth. 

On to the Moon!  The Moon is unusual among solar system moons in its relative size to it's primary.  The most widely accepted explanation for the Moon's unusual size is that, approximately 4.5 billion years ago, a Mars-sized planet called Theia collided with Earth in a clanking blow, creating a field of debris from both Theia and Earth in orbit of Earth, which later coalesced into the Moon. 
The color of the Moon is surprisingly deceptive, it looks like a light grey, but it's actually an asphalt color:

The gravity on the Moon is about one sixth of Earth's gravity.  The plane wouldn't be able to fly, because of the lack of atmosphere.  The boat wouldn't be very interesting, because the lunar "seas" or "mares" are made out of hardened basalt flows.
The human would need a spacesuit, because of the lack of oxygen, and the temperature, ranging from 242 degrees F (100 K) during the day to -280 degrees F (100 K) during the night.  We know this is possible, because of the Apollo Moon landing program.  The house shouldn't have too much trouble, but probably cycles of hot and cold and solar radiation would eventually wear it down.
The Moon is habitable enough that food and water could be a problem.  Food would have to be brought with you, or farmed in a pressurized greenhouse.  Water is a problem, because at the equator, water wouldn't last very long, not near the surface, anyway.  However, at the lunar south pole, there are craters where sunlight never reaches the bottom.  This is a likely location for water ice, because that strong evidence for water ice has been found there.  Also, because sunlight never hits the bottom of the craters, a lunar base would have to deal with less temperature extremes. 

That's it for the Earth and Moon, see you on Mars!

Monday, October 5, 2015

Project Apollo Archive


The Project Apollo Archive (Which has amazing images of spaceflight stuff) recently added a flickr gallery with over 10,000 HD scans from film taken during project Apollo.  Enjoy.

Thursday, October 1, 2015

Rocket engines

Today we're going to look at rocket engines.  Rocket engines are some of the most complex things in existence.  They operate at incredible extremes, and yet they are very complex.  Here's a test fire of a Merlin 1D rocket engine:

A rocket engine is very similar in concepts to a jet engine, with one difference: A jet engine collects oxidizer from the ambient air, but a rocket is completely self contained and self propelled.  It carries all its fuel with it, so rocket engines have to combine fuel and oxidizer, ignite it, and propel it out at supersonic speeds.

The concepts behind rocket engines are simple, if not the implementations.  A rocket is a lot like an inflated party balloon.  The air in an inflated balloon is the fuel.  It stretches the rubber skin, adding potential energy, and then is propelled by that energy out of the hole in the balloon, and the mass expelled from the balloon drives it across the room.  Technically, a balloon is a pressure fed, monopropellant rocket.

There are a lot of kinds of rocket engines, but we'll start by looking at the most common kind: The liquid bipropellant rocket engine.

The fuel and oxidizer from the rocket's tanks are sucked from the tanks by high speed turbopumps. To give you an example, the J-2X hydrogen turbopump produces an incredible 16,000 horsepower.  Where they go from there depends on the rocket.  Somehow, the fuel is expanded to propel the turbo part of the turbopumps, either by being burnt with the oxidizer in a small combustion chamber and then sent to the turbopumps, if it's a gas generator cycle engine, sent around the engine to be heated up if it's an expander cycle engine, or fed through a pre-burner, which is very similar to a gas generator, except that the exhaust is fed back into the main combustion chamber to be burnt again after it's been used to power the turbopumps.
This is only a very basic overview of the different ways of dealing with turbopumps, for a more in-depth look at it see this blog's post.  Actually, read all of the posts.  No really, this is an great blog.  All of the posts are interesting and relevant, especially to this post.  Also, look at this video, from Copenhagen Suborbitals:

The fuel (and sometimes oxidizer) is then pumped through tubes in the walls of the main combustion chamber (MCC) and the nozzle walls.  After that, it gets really interesting.  The fuel and oxidizer is then combined and burnt in the MCC.  The cold fuel flowing through the walls prevents the MCC from melting. 

When fuel and oxidizer have been burnt in the MCC, the combustion products are forced out of the MCC, into the throat of the nozzle.  This part is like that thing that you can put on the end of a garden hose to increase the fluid speed and decrease fluid pressure.  This is known as the Venturi effect.  However, the Venturi effect only works with subsonic fluids, if the fluid is supersonic, the flow "chokes" because the pressure waves that cause the Venturi effect no longer propagate upstream, instead, a diverging tube will increase speed and decrease pressure at supersonic speeds.  This is the principle that makes the de Laval nozzle work, which is used in most liquid rocket engines.  It is named after a Swedish inventor, Gustaf de Laval.
Here's a picture of a cross section of a de Laval nozzle:
"Laval-nozzle-(longitudinal-section-of-RD-107-jet-engine)" by Albina-belenkaya - Own work. Licensed under CC BY-SA 4.0 via Commons.
You can see how, after the exhaust has been accelerated to supersonic speeds by the nozzle converging from the MCC at the top of the picture, the nozzle diverges to further increase the speed.
Again, take a look at this blog for a more in-depth article about this.

Rocket engines are built differently for different environments.  At sea level, engine nozzles are shaped differently than vacuum engine nozzles, because that the ambient pressure is higher, so nozzles need to be shaped differently to get the most thrust in the environment it's designed for. 

Some rockets have hydraulic actuators which swivel the engine to provide steering while the engine's providing thrust, by changing the angle of thrust through the rocket.  The hydraulic actuators are powered by the rocket engine itself.  Here's a video of a J-2X engine being gimbal tested:

So how do you provide fuel to an engine that's rotating relative to the tanks?  By using pipes with bellows.  It seems pretty simple, except you have to remember, these pipes have less than -183 degrees Celsius liquid oxygen being forced through them, and, in some engines, even colder liquid hydrogen being pumped through them.

I'll finish this post with a video of a Copenhagen Suborbitals rocket being explained (This is a pressure fed, liquid chemical bi-propellent rocket engine):

Curious about what happened in the test?  Look here.

Tuesday, September 22, 2015


The second planet from the Sun, Venus is even worse for stuff than Mercury is.  First of all, the gravity is almost the same as on Earth, so that wouldn't be a problem.  Unfortunately, you would still be crushed by 1,322 PSI or 90 atmospheres of pressure at sea level, which is about the same as 900 meters below the surface of the ocean.  Handily, it's very easy to calculate approximate atmosphere pressure in sea water, since pressure in atmospheres is almost one-tenth of depth in meters, but it's not exact, so you can look at this for your pressure calculations:  Or this to do the calculations yourself:

It seems that it would be impossible for humans to survive the pressure, but perhaps they could!  An intriguing page talks of exposure of mice to 90 atmospheres of pressure, with survival of the mice.  A couple of google searches later, I found this, however, the link to the PDF appears to be broken.  Then I found out that the article is from Science magazine, in the 5 June 1964 issue.  To download the PDF, you need to be subscribed to Science magazine, which I am not.

This is what happens to a Styrofoam cup at 2300 meters:

Probably the house would collapse from the pressure, but it would be possible to build a habitat that could withstand the pressure, like a research submarine.  Lava flows are the closest to oceans that Venus has, and there's no way that a boat could survive floating on lava.  What would happen to the plane is neatly summed up by What If, and also segues to our next problem:
Your plane would fly pretty well, except it would be on fire the whole time, and then it would stop flying, and then stop being a plane.
The other problem with Venus is the heat.  Its mean surface temperature is 735 K, hot enough to melt lead.  You could survive for a short time in another kind of Fire proximity suit if it weren't for the pressure.

However, above the clouds, they say that Venus is surprisingly like Earth, albeit a Earth with sulfuric acid, unbreathable atmosphere, and category-5 hurricane winds.  It's so much like Earth that NASA has a Venus exploration plan using airships, known as HAVOC (High Altitude Venus Operational Concept):

Conclusion: Venus is hard, but not impossible, as long as you're okay with not going to the surface.

Saturday, September 12, 2015

Looking at the Earth

That is the ISS HD Earth viewing experiment you see directly above.  It is a experiment to determine how quickly HD video camera image quality degrades when exposed to the space environment (mainly from cosmic ray damage) and verify the effectiveness of the design of the HDEV housing for thermal control.  The people behind the project kindly broadcast the video, which shows stunning images of Earth.

For a long time, most space photography was looking up, at the Moon, the Sun, and other astronomical objects.  Then, on Oct 24, 1946, a captured V2 was launched from New Mexico's White Sands Missile Range, with a camera taking photos every 1.5 seconds.  The camera was destroyed on landing, but the images survived.  This is the first image of Earth from space:

Since then, there have been thousands upon thousands of photos of Earth from space.
See here for some iconic ones, and see here to browse tons of photos of Earth. 
Why do astronauts love to take pictures of Earth?
Something called the Overview Effect.   To learn more about it, look here, (While you're at it, look at their image-a-day service here)
Then look here:

And here.

Of course, most of this is from low Earth orbit, there are plenty of pictures from farther away:
The Blue Marble
The Day the Earth Smiled
And Pale Blue Dot

Monday, September 7, 2015


Mercury is the closest planet to the sun, and also the smallest planet, about the size of the Moon.  It's gravity is about 38% of Earth's gravity, so if you were the world's high jump champion, you could jump 6.4 meters.  But you're probably not the world's high jump champion, so if you divide your jump height by 0.38, that's how high you could jump on Mercury.  You will probably get something like 1.2 meters, if you're between 20 and 30 years old.  Long story short: Averages are hard.

Anyway, all that means that you could dunk a basketball almost without raising the ball above your head. 

So, the human, and the structures would be fine in the gravity.  Mercury has no atmosphere to speak of, so the airplane would be useless, and since there are no oceans on Mercury, the boat wouldn't be very interesting.  The house could stand in the gravity, and the lack of atmosphere wouldn't affect it, but the heat would.

The temperature:
Because of it's proximity to the sun, the temperature varies wildly between day and night, with 100 K (−173 °C; −280 °F) temperatures at night to 700 K (427 °C; 800 °F) temperatures during the day at some equatorial regions.  That's definitely too hot for most of the house, but you could survive in something like a fire proximity suit.  The house could survive if it was made out of something with a higher melting point than tin.  At night, a spacesuit would be necessary.

Mercury has been suggested as a colonization site, as it has lots of solar power, not terribly unreasonable temperatures near the poles along with possible ice deposits, and possible deposits of Helium-3. 

In short, Mercury would be fairly survivable, with proper equipment.

Friday, September 4, 2015

Welcome the starliner!

The boeing starliner artist's concept
Welcome the Starliner!

Boeing's new LEO spacecraft, previously known as "CST-100," has received a name!
The Starliner will deliver crews to and from the International Space Station (ISS) or a private space station, as a replacement for the Space Shuttle.  It can carry seven people at a time, and be reused up to ten times.  It is expected to fly to the ISS crewed for the first time in 2017.

Read more here, and here.

Wednesday, September 2, 2015

Specific impulse

Our topic for today is another rocketry concept: Specific impulse (usually abbreviated Isp).  Basically, it's how efficient your rocket engine is.  It's defined by how far each unit of fuel moves your rocket.
Here's the formula:
Isp equation  Where:
  • I_{{sp}} is the specific impulse in meters per second
  • F_{T} the thrust in newtons
  • {\dot  m} the fuel consumption in kg/s
So, Isp is how much thrust you get per unit of fuel.

If your Isp is higher, then you can get more Delta-V with the same rocket.  In the rocket equation, v_\text{e} is used instead of Isp, but the concepts are the same. 

Saturday, August 29, 2015

The sun

The first body in the solar system is the sun.
It is a ball of plasma, it's radius is 109.2 times larger than earth.  It accounts for 99.86% of the total mass of the Solar System.  It's surface gravity is 28 times earth's.
Now, on to the facts that really make the difference to our human, house, boat, and airplane.
The surface temperature is 5,800 K.  That's 9980.33 °F or 5526.85 °C.
How hot is that?

What?  What was that?  You want me to write something?  Sorry.  Just getting lost in youtube.
Essentially, plasma is fire:

So, what would happen to anything on the surface of the sun?  Well, around 5800K, carbon atoms are ripped apart. 

First, the gravity:
The sun has 28 times the gravity of the earth.  A typical person can stand about 5g before losing consciousness, and with training and specialized clothing you could withstand 9g.  However, at 28g you would not even be able to stand.  You would quickly be killed, if only by the fact the the heart is not strong enough to pump blood around your body at 28g.  The heat would kill you, quickly, but sometime after a nanosecond.  Because of the heat in the sun, photons would have very short wavelengths.  Those would ionize your DNA, which is not good.  Cancer is the least of your problems.

I think that our building could theoretically stand up, especially with reinforcements, since a 1 story house would only weigh about as much as a 28 story house, which is perfectly possible on earth.  In fact, it could be more stable than a 28 story house, since it's closer to the ground, and therefore more stable.  Too bad it's rapidly being converted to plasma by heat and radiation which rips apart the very molecular bonds inside the walls.

Similar things happen to the airplane and the boat, and since there's no oceans or atmosphere high enough for the plane to not be vaporized, they're not very interesting.

At the very least, you might trigger a solar flare:

See you on Mercury!

Thursday, August 27, 2015

The size of space

Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space.
-Douglas Adams

Space is as infinite as we can imagine, and expanding this perspective is what adjusts humankind’s focus on conquering our true enemies, the formidable foes: ignorance and limitation. 
-Vanna Bonta

Today we have an interesting topic; How big is the solar system?

You might be familiar with maps of the solar system like this:
Classic view of solar system, out of scale.

But if you want to know really how big the solar system is, take a look at this map, with the moon the size of a pixel, and everything else to scale:
If you have 297 minutes, you can travel it at the speed of light.  Or, perhaps, 177,632,973,808.5 Blue Whales

Such misconceptions run rampant, as shown here:

Next, take a look at the 70's classic short scientific film: Powers of ten

For the more interactive of you, here's a fascinating scrollable scale from the planck length to the observable universe.  There's some interesting stuff in there, for example: A marathon is longer than Phobos.

So, yes.  Space is truly massive and almost empty.  Remember, any solar system is incredibly dense by cosmic standards.  Want to explore it yourself?  See Celestia  For a example of the challenges in spaceflight, take a look at Kerbal Space Program  If you are playing Kerbal Space Program and feeling a lack of challenge, try the Realism Overhaul modification.

Now that you know how big space is, you can see how many humans are in it right now.  And then watch this awe-inspiring video:

So, why all this preamble?  Because I'm going to start a series of posts on what would happen if a plane, a boat, a human, and a building were transported to every large body in the solar system.
Invaluable for this will be What If's posts Interplanetary Cessna and Extreme Boating

See you on the sun, with a 747, a condo, and a sailboat.

I was recently linked to by the blog Way Of The Dodo


Tuesday, August 25, 2015

Launch alert! GSLV Mk. 2 • GSAT 6

The Indian Space Research Organization (ISRO) will be launching a GSLV into geosynchronous orbit with a GSAT as the payload.  It will launch from Satish Dhawan Space Center, Sriharikota, India.  The GSAT is a communications satellite which will used for digital audio, data and video broadcasting.

Download mission brochure.

The launch was a success.

Sunday, August 23, 2015

Curiosity on Mars

Today we have a picture of the rover Curiosity on Mars.
This picture was taken by a camera on the end of Curiosity's robotic arm, the camera is designed to take close-up images of details on rocks, but it can also rotate to image the rover itself.  It took many pictures, which were stitched back together after they were transmitted back to earth.  Only the shadow of the robotic arm is visible because it can rotate out of the image area.

Saturday, August 22, 2015

Thrust to weight ratio


Today we have another post on rocket science concepts, thrust to weight ratio! (Yes, I play Kerbal space program, if you haven't already guessed.)

Thrust to weight ratio (let's call it TWR from now on) is a concept in rocketry.  It is how much thrust the rocket has to how heavy it is.  If you have engines totaling 100 pounds of thrust, and 100 pounds of rocket (Including engines) you will have a earth TWR of 1.  That means that at sea level, your rocket will hover, exerting no force upon the ground (aside from the rocket exhaust quickly making a crater), but appearing to rest on it.  As the fuel inside your 100 pound rocket burns, your TWR slowly increases, and you begin to rise slowly.  Because of the natural logarithm, your rocket will rise faster as it burns fuel.  Also, as it rises, there will be slightly less gravity exerting it's force on it, and it will rise faster. 

Here's the math:
{\text{TWR}}={\frac  {F_{T}}{m\cdot g}}>1
This formula is more simple, and only requires this to be understood: F_{T} is the thrust of the engine, m the total mass of the craft, and g is the local gravitational acceleration (usually surface gravity).

The unladen mass of a rocket engine is generally very high, since it needs to lift all that fuel.  Wikipedia has a nice table on that. 

TWR can be calculated for anything, for example, airplanes, machine guns, sci-fi, and video games:

(Note that the math for surface acceleration is definitely not guaranteed for earth rockets)

Friday, August 21, 2015

InSight lander

Get frequent flier miles with NASA! 
Put your name on a list of names which will be on a microchip on the InSight mars lander when it lands on the red planet on September 28, 2016.

The InSight lander is a probe similar to the 2007 phoenix lander, but this one has several new instruments intended to find out about the early geologic history of Mars.

Thursday, August 20, 2015

Welcome to Delta-V!

Hello, Readers!

This is my blog on rocket science, astronomy, and spaceflight!  I will post interesting space news for your entertainment. 

The name of my blog, Delta-V, comes from the basic piece of math from which most rocket science is based; The Tsiolkovsky rocket equation.  Which is, quite simply, a way of finding out how far a rocket could get, in a perfect universe.  It looks like this:
\Delta v = v_\text{e} \ln \frac {m_0} {m_1}
It's named after Konstantin Tsiolkovsky, just so you know.
Don't worry, it's not as bad as it looks.
Let's unpack it.  First, moving from the left to the right, we have this symbol: ΔIt is pronounced delta-vee.  That is the mathematical way of describing change in velocity.  If a spacecraft has a Delta-V of 1,200m/s, then, if it was in a gravity free vacuum, it would be traveling at 1,200m/s after it had burned all of it's fuel. 

Now, we have the rest of the equation, starting with v_\text{e}, which is the effective exhaust velocity.  In other words, how fast the exhaust from the rocket comes out.  The faster it comes out, the more efficient the rocket is. 

Then there's \ln, which is the natural logarithm, and that accounts for the fact that the rocket accelerates faster as it uses up fuel.

Finally, to factor in the mass fraction, which is how much fuel mass to ship mass there is in the ship.  If it's higher, there is more "stuff" to be used for propellant.

If you add it all together, you get a formula which can tell you how far your rocket can go.

And here are some people who explain it better than I:
Randall Munroe
William Greene
Don Pettit