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Traveling to Other Worlds

For the final post of the semester, I thought it would be interesting to look at space travel beyond Earth orbit. Contact with extraterrestrial life, or just visiting other worlds, is a topic that has been floated around in both the public and professional circles for quite a while now. Following the successful landings on the Moon, missions to Mars and other objects in our planetary neighborhood captured the imaginations of many. Furthermore, while America’s manned space program is currently in a bit of a hiatus, the planned successor to the Space Shuttle, the Space Launch System, is being designed with the hope of transporting astronauts beyond the confines of low Earth orbit.

Towering at a height of 363 feet and weighing in at staggering 6,699,000 pounds, the Saturn V remains the most powerful rocket ever used for manned spaceflight. Its three stages provided a total of 8,873,000 pounds of thrust to transport 3 astronauts from the Earth to the Moon (fast forward to about 6:57 in the video above for footage of the launch of Apollo 8).

Size wasn’t the only thing that made the Saturn V a marvel of engineering and exploration. The very act of getting to the moon required a level of execution simply unimaginable. One of my friends knew someone who worked at NASA during the Apollo program. The way he described it was that trying to hit a dime across a football field with a bottle rocket was significantly easier than going to the Moon, and nobody died if you screwed up.

Obviously, the challenges of going to Mars and other worlds will be much greater. The designing of a rocket and capsule for this voyage depends on a variety of factors, perhaps the most important being the utilization of the Hohmann transfer orbit. I mentioned this in an earlier post. Basically, this is the method used to take a spacecraft from the orbit of one object to another. The Hohmann transfer offers the most efficient utilization of resources (i.e. fuel) for this process. Missions would have to be planned around this orbit, both for the journey to and the return from another world.

Source: The Astronomy Cafe

The duration of this kind of trip is also much greater than that of the Moon missions. The crew of Apollo 11 took about 4 days to journey to the moon. A trip to Mars would take about 9 months. When traveling through space, crews must take everything with them, as there is no hope of refueling or restocking on items such as food and water. The design must account for extensive travel through the harsh void of space (radiation and cosmic debris are no joke). The mission must also take into consideration activities done when reaching the planet, whether it be staying in orbit or landing on the surface. And then, of course, there is the return leg of the journey. After all, what good is getting the chance to go to Mars if you don’t get to come home and tell people about it?

In short, planning for this thing is a logistical nightmare. But, I think it is possible. We have used telescope and probes to explore the our universe. The next logical step is sending people to observe these things first-hand. It will take a lot of time, money, and effort. Then again, so does any worthy endeavor.

The launch of Apollo 11, July 16, 1969 (Source: NASA)

Best of luck to everybody on the final.

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The End of the Space Shuttle: What Got Us Here

Source: The Denver Post

As some of you probably know by now, the Space Shuttle Discovery made its final flight today, being transported to Washington D.C. for display at the Steven F. Udvar-Hazy Center of the Smithsonian Air and Space Museum. Space Shuttle Atlantis STS-135 marked the last spaceflight of the orbiter fleet. Watching Discovery being transported kind of hammers home the fact that this is the end of an era (as brought up by another Astro 201 blogger). Since this is such a pivotal time in space exploration for our country, I thought it would be good to go back and look up the events that set in motion the retirement of the shuttle fleet.

On February 1, 2003, the Space Shuttle Columbia catastrophically disintegrated over the southern U.S. sky while returning home after completion of STS-107. It was the second accident resulting in fatalities for the shuttle program (the first being STS-51-L Challenger). The Columbia Accident Investigation Board (CAIB) was convened to investigate what caused the the destruction, comment on the state of the program as a whole, and outline any improvements needed. The CAIB determined that the shuttle did not need to be scrapped. However, it did make one key recommendation: given the age and wear on the orbiters, if the shuttle was to be used beyond 2010,  it needed to undergo recertification.

NASA had already looked into retiring the fleet before the 2003. Crucial to understanding the current situation is that the administration always did so with the feasibility of replacement in mind. For exampling, with all of the setbacks to the Lockheed-Martin X33 (and the VentureStar), NASA actually moved the retirement year to 2020 and commissioned studies to identify what had to be done to create a suitable successor to the orbiters. In light of the Columbia disaster, the CAIB stated that it was “… in the nation’s best interest to replace the Shuttle as soon as possible as the primary means for transporting humans to and from Earth orbit.”

Nearly a year after the Columbia disaster, President Bush presented his Vision for Space Exploration (VSE). For this new plan, The Bush administration used the CAIB’s 2010 benchmark as their own mandatory deadline for retirement of the shuttle fleet. Both the CAIB and the Bush administration recognized the shuttle’s importance in the construction of the International Space Station. The CAIB’s 2010 deadline stemmed from the fact that the ISS was expected to be complete by that year. Yet, this turned out to be unfeasible. The difference between the VSE and the CAIB recommendations was that the CAIB did not explicitly advocate for bringing an end to the program in 2010. Recertification may have been a hassle for NASA, but it sill left the door open for the shuttle to keep flying. The CAIB’s goal in pushing for recertification was that it would introduce a formal process for extending the lifetime of the shuttle fleet. The VSE did not share this attitude of flexibility. Essentially, the Bush administration’s plane forced NASA’s hand to abandon its existing operational launch system, as  NASA’s receiving of budget outlined in the VSE required termination of the shuttle program.

Side note: President Obama had to extend the shuttle’s service by a year due to delays in shuttle missions and after it became clear that NASA needed the extra time.

The result was NASA, for the first time in its history, bringing an end to a program without a viable successor in the works. To put the matter in perspective, NASA had begun studies into developing the shuttle back in 1969, during the height of the Apollo program. In 1972, Nixon signed off on allowing NASA to develop its new space transportation system. The Constellation program, the intended successor to the shuttle, was conceived of in a time when the agency was preoccupied with disaster recovery. It never received the budget it needed, and the combination of planning setbacks and monetary concerns led to cancellation of its funding under the Obama administration.

Currently, NASA’s future plans for manned space exploration revolve around the Space Launch System. Unmanned missions are slated for launch in December of 2017. Until then, our astronauts will have to turn to other space agencies, such as Russia’s, to leave the confines of Earth.


Science Education and Tennessee Legislation

There is currently a controversy brewing in the state of Tennessee and the education of its children. HB 368 attempts to address the fact that “teaching of some scientific subjects, including, but not limited to, biological evolution, the chemical origins of life, global warming… can cause controversy.” In other words, this bill allows teachers to approach topics which have been extensively studied and evaluated by the scientific community and treat them in the complete opposite manner. The bill passed through the Tennessee legislature and, as of today, April 10, 2012, stands to pass as a law. Governor Bill Haslem opted not to veto the bill, despite opposition from the scientific community within Tennessee and throughout the country.

There’s two reasons why this matter stands out for me. 1. I’m an evolutionary biology major. As a senior, I’ve spent the majority of my time here at Vanderbilt taking courses which not only satisfy the prerequisites for that major, but also provide  me with the understanding of this intricate, and, quite frankly speaking, beautiful, subject. What I can tell you right now is that any individual approaching evolution as a controversial theory is doing so with ulterior motives. Are there gaps in the biological record? Yes. Has the entire picture been uncovered? No. But evolution is accepted by the scientific community for the same reason the theory of gravity is accepted: it does the best job explaining the evidence and observations that have been gathered over time.

How does this relate to astronomy and physical sciences? Well, global warming happens to be another “controversial” topic targeted by this piece of legislation. We’ve gone over global climate change and warming somewhat in Astronomy 201. As with evolution, the science is not perfect. But, the multitude of studies and data point towards its tenability. Furthermore, as with evolution, any controversies brought forth are from parties and individuals with ulterior motives. They don’t question the science for the sake of knowledge. They question it because discrediting it works in their favor.

The bill states that it “shall not be construed to promote any religious or non-religious doctrine…” in what I assume is an attempt to placate the scientific community. Except that’s exactly how it should be viewed. By allowing teachers to debase widely-accepted theories as they see fit, it opens the doors for agendas, both religious and non-religious, to undermine knowledge. When discussing the bill’s impact on evolution, Vanderbilt’s own Jon Kaas and Roger Cone, along with Robert Webster of St. Jude Children’s Hospital, have stated that “The Tennessee legislature is doing the unbelievable: attempting to roll the clock back to 1925 by attempting to insert religious beliefs in the teaching of science…” 1925 refers to the year of the Scopes Trial. And, I can’t stress this fact enough, global warming is in danger of suffering the same predicament, albeit from other sources (in this instance, religion is usually not the source of dissent).

The European Journal of Public Health ran a fantastic piece regarding denialism back in 2009, stating that “There is overwhelming consensus on the evidence among scientists yet there are also vocal commentators who reject this consensus, convincing many of the public, and often the media too, that the consensus is not based on ‘sound science’ or denying that there is a consensus by exhibiting individual dissenting voices as the ultimate authorities on the topic in question… denialism… [is] the employment of rhetorical arguments to give the appearance of legitimate debate where there is none, an approach that has the ultimate goal of rejecting a proposition on which a scientific consensus exists.” This is what HB 368 promotes, and this is why it is a mistaken and detrimental piece of legislation.

Critique and debate over theories is the backbone of scientific learning and progress. However, these must conform to the spirit of scientific inquiry. Just as a chemist will not entertain dialogue with an alchemist, an astronomer with an astrologist, and a historian with a misguided revisionist, biologists and biology teachers should not be discussing so-called criticisms until the proponents behind those ideas utilize the proper means to garner some semblance of validity (Myers, 2009). Similarly, climatologists and teachers should not entertain debates until the other side puts forth a logical, scientifically grounded rebuttal. There is a big difference between discussing “outlying data” and discussing the subject as a “controversy.” There is a big difference between promoting healthy skepticism and treading over to the realm of ill-advised skeptical denial.


Space Wants You Dead

Space travel is a risky endeavor. Everybody knows that. Rockets can explode or malfunction and crash. A spacesuit is the only thing standing between an astronaut and the unforgivable void surrounding him/her when outside the spacecraft. It takes an incredible level of planning, coordination, and execution between the astronauts and ground personnel to keep a mission on the right path.

And even then, space is just biding its time, like a mad scientist nefariously rubbing his hands together, just waiting to unleash an attack, making it very clear that when you venture into its domain, you’re never truly safe. Here are just a three odd ways it can ruin your day:

Debris/Junk: Wouldn’t it suck to have your spaceship crash into a satellite? NASA certainly thinks so, which is why they have mapped out orbital debris, i.e. space junk. There’s a ton of it in Earth orbit:

Source: NASA

So, they’re being tracked. Problem solved, right? Not exactly. Those are all the objects large enough to be tracked. Anything smaller than a softball is not found in that image above. And in space, even the small things can make a big impact:

Source:  NASA

That’s what happened to one of the windows of Space Shuttle Challenger during STS-7. A fleck of paint, traveling at around 11 kilometers per second, caused enough damage to force the replacement of the entire window. It isn’t a stretch to say that a well-placed blow can cripple a spacecraft.

If Something Goes Wrong and You’re Not In Earth Orbit, Tough Luck: Quick, what’s Newton’s first law of motion? An object in motion will stay in motion and an object at rest will stay at rest unless acted upon by another force. On Earth, your car can’t be in perpetual motion without you pressing on the accelerator because friction is counteracting its forward (or reverse) motion. So, at some point in time, your car will stop. Now, let’s say instead of traveling in a car on Earth, you’re in a spaceship on your way to Pluto, like the New Horizons spacecraft. If something goes wrong, cross your fingers that you get captured by a planet and start orbiting it, because the other choice for slowing down is straight-up crashing into something. If fate decides to give you a break and you do end up circling, let’s say, Jupiter, you’ll still have to wait over a year for the rescue ship to reach you.  That’s how long it took New Horizons to reach Jupiter. Even if fate decided to give you a much bigger break and left you orbiting Mars, you’re still looking at a 9 month wait. If this still doesn’t sound that bad, keep in mind that these times are estimated/accomplished using the Hohmann transfer orbit. Essentially, this is the easiest way to get a spacecraft from Earth orbit to the orbit of another planet/object. Here it is, illustrated for Mars:

Source: The Astronomy Cafe

You can’t just point to Mars/Jupiter/whatever and hope for the best. Also, up until now, we’ve been assuming that the folks back on Earth have a craft ready on stand-by. Chances are, they won’t. After completing STS-123, Space Shuttle Endeavor underwent 9 months of servicing before returning to the Kennedy Space Center for its next mission. Even disposable rockets, such as Apollo’s Saturn V, still require time to construct and ready for spaceflight. The shortest window between launches during the Apollo Program was about 2 months (accomplished between Apollo 10 and 11). So, taking into consideration the time it takes to prepare a mission and for travel from Earth to you, stock up on as much food and other essentials as possible. It will be a while.

Oh, and if you’re not captured by another planet and are zooming through space unimpeded, forget about rescue. New Horizons is traveling at about 37,000 miles per hour. Voyager 1 clocks in at 38,136 miles per hour (relative to the sun). So, any spacecraft launched to bring you back must travel significantly faster than you. We don’t have the technology to pull that off.

Kidney Stones: Huh?

Yes. Kidney stones. Stones form when urine is saturated with certain dietary minerals, calcium being one of them. The excess minerals can concentrate or crystallize into a variety of sizes (obviously, bigger is not better). In the zero-gravity environment of space, the human body has a tendency to lose the calcium in the bones. In fact, astronauts can lose between 1-2% of their bone mass per month, even with exercise (Nimon, 2012). That calcium has to go somewhere. And, if they’re particularly unlucky, it ends up forming kidney stones. I think it’s safe to say that the last place you want to experience this condition is a couple hundred miles above Earth and the nearest doctor’s office.

Source: Wikipedia

Pietrzyk et al. (2007) write that in the U.S. space program “have experienced 14 renal stone episodes in 12 astronauts (10 men, 2 women) with 9 stone events occurring in 7 crewmembers post flight (2 crewmembers had 2 postflight stones).” NASA considered it enough of a problem to conduct a study on astronaut physiology, calcium loss, and treatment with potassium citrate during spaceflight. Along with supplements, astronauts are recommended to increase their water intake as this would dilute the concentration of calcium and other minerals in their urine. Still, the risk has not been totally eliminated. Remember, space travel isn’t some exercise in luxury. The astronauts going up there undergo extensive training, not only pertaining to their roles for the mission but for general and emergency protocols. Everybody needs to be on top of their game. Space isn’t the place to have your mind focused on other matters, such as the excruciating pain from having one of those things wrecking your urinary tract.

So, there you have it. Three odd ways space can mess you up. Full disclosure: this post was inspired by this Cracked.com article (CAUTION: NSFW LANGUAGE). I picked the three I found most interesting and decided to do a little bit more research. If you want to read some of the others Cracked decided to list, go ahead.


The Coolest Stars in the Universe

Source: NASA

Stars are really, really, hot. This is something you should know by now. Our own sun has a surface temperature of about 9,900 degrees Fahrenheit, and, it gets hotter the closer you get to the core. Of the multitude of stars in the universe, some are bigger than the sun, others are smaller, some are hotter, others are cooler. Yet, as far as we’re concerned, they’re all still really hot compared to the temperatures we face here on Earth… right?

WRONG!

Not all of them. Basically, there’s this group of celestial objects called brown dwarfs. “Normal” stars, like our sun, release energy through hydrogen fusion. Scientists think that a brown dwarf begins its life like any other star, collapsing under its own weight into a dense ball of gas (NASA, 2011). Yet, brown dwarfs lack the mass required “to fuse atoms at their cores and thus don’t burn with the fires that keep stars like our sun shining steadily for billions of years.” (Calvin & Perrotto, 2011) For this reason, they are often called “failed stars.” These objects have masses ranging between 15 to 75 times that of Jupiter. Some are capable of fusing deuterium, while others fuse lithium. They’re… odd. To say the least.

Because they don’t derive energy from hydrogen fusion, these stars are much cooler than their relatives. In March of last year, researchers at the University of Hawaii found a brown dwarf with a surface temperature of 206 degrees Fahrenheit. That’s about the same temperature as a freshly brewed cup of coffee. Just a few month’s later, NASA’s Wide-field Infrared Survey Explorer (WISE) discovered another cold brown dwarf (circled in the picture below). Its temperature was determined to be about 80 degrees Fahrenheit. For now, this is the coolest star ever discovered.

Source: NASA

Finding brown dwarfs is a tricky exercise. Because they don’t conduct fusion reactions like normal stars, you can’t look for them by relying solely on visible light. These stars are so cool they emit infrared light, and even with the proper equipment they can still be difficult to see. What makes these objects particularly fascinating is that, for the most part, we envision space to be vast swaths of nothingness. Sure, there are an innumerable number of stars, planets, and other objects in the universe, but the distances between objects in space are extraordinary. Brown dwarfs suggest that the universe is slightly more crowded than we originally thought.

So, there you have it. Stars which are cooler than a pot of boiling water, or even a hot summer day here on Earth. The universe is weird like that.

For more reading, see:

http://www.nasa.gov/mission_pages/WISE/news/wise20110823.html

http://news.nationalgeographic.com/news/2011/03/110323-coldest-star-discovered-cup-coffee-brown-dwarf-hawaii-space-science/

http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question62.html

http://gizmodo.com/5785275/this-star-is-so-cold-that-you-can-actually-lick-it

http://gizmodo.com/5833893/nasa-discovers-sweater-weather-star

http://earthsky.org/space/stars-are-hot-right-not-this-star


A Closer Look at Titan

In my previous post, I made a mention of Saturn’s moon Titan being a possible host for extraterrestrial life. Turns out that Titan was discovered on this very day, March 25, back in 1655 by the Dutch astronomer Christiaan Huygens. Given this fact, I thought it would be fun to take a closer look at this moon. What’s so special about it? Why do astronomers think it could harbor life?

Source: NASA

A major point of interest is that Titan is the only moon discovered so far that has a substantial atmosphere. It’s atmosphere is about 1.5 times as thick as Earth’s and, like Earth’s, is dominated by nitrogen (McKay, 2005). Along with nitrogen, the atmosphere is rich in organic compounds such as methane and other hydrocarbons (Lemonick, 2010). Obviously, these conditions are very different from what we see here on Earth, but astrobiologists think that  the atmosphere provides precursors for, and can sustain, life. Experiments conducted at the University of Arizona have demonstrated that DNA/RNA bases cytosine, adenine, thymine, guanine, and uracil and amino acids glycine and alanine can be produced from the ingredients in Titan’s atmospheric haze (2010).

Source: Wikipedia

Interestingly, Titan’s surface is devoid of liquid water, which seems to argue against its ability to support life. Yet, others argue that life can exist in the liquid methane lakes that dot Titan’s surface, shown in the image above. These lifeforms would use acetylene, ethane, and other organic solids in combination with hydrogen to derive energy for sustenance (McKay & Smith, 2005). Supporting this idea is the fact that certain lifeforms on Earth, microorganisms called methanogens, exist in a similar manner. The science behind this theory is very dense, so I won’t write it all out here. Instead, I refer you to the  2005 paper written by McKay and Smith which discusses the matter. Furthermore, while the surface does not have water, scientists believe that Titan does have a global subsurface ocean, composed of a water-ammonia mix. As Fortes (2002) writes, conditions within this hypothetical ocean, while extreme by terrestrial standards, are such that life could indeed survive.

In 2005, the Huygens probe landed on Titan’s surface, marking the first landing done in the outer solar system. Atmospheric and surface data obtained by Huygens possibly indicated the presence of methanogen-like life (McKay, 2010). However, abiotic chemical or geological processes cannot be completely discounted. Ultimately, it will take many years of study and exploration to uncover Titan’s secrets. But, if what’s been discovered so far is any indication, the undertaking promises to yield intriguing results. I, for one, am hoping that life is one of them.

To read more:

http://en.wikipedia.org/wiki/Life_on_Titan

http://www.astrobio.net/index.php?option=com_retrospection&task=detail&id=1755

http://www.astronomy.com/en/sitecore/content/Home/News-Observing/News/2010/10/Titans%20haze%20may%20hold%20ingredients%20for%20life.aspx

The article by McKay and Smith: http://www.sciencedirect.com/science/article/pii/S0019103505002009

The article by Fortes: http://www.sciencedirect.com/science/article/pii/S0019103500964005

http://www.spacedaily.com/reports/Have_We_Discovered_Evidence_For_Life_On_Titan_999.html


Life Elsewhere? Perhaps in Our Solar System?

Source: Time Magazine

The possibility of life existing elsewhere has fascinated human beings since… well, since humans have been on this planet. With the advancement of space study and exploration, many astronomers have turned their attention to finding planets (or other astronomical bodies) with life. For example, there is the extrasolar planet Gliese 581g. Located 20 light-years away from Earth, 581g orbits within the habitable region around its star and has enough mass (3 times that of Earth) to retain an atmosphere capable of supporting life. There’s also the ongoing SETI (Search for extraterrestrial intelligence) project. The Voyager probes carried golden records which contained scenes, greetings, music, and sounds from Earth for would-be alien listeners. To date, these searches, and others, have not proven fruitful. Yet, personally, I think these are worthwhile endeavors and that, sooner or later, they will pay off. Think about it. Our universe is so vast that it is a virtual certainty that life exists, somewhere out there. The odds that our small corner in the cosmos turned out to be the only place to hit the biological jackpot are ridiculously small.

That said, maybe we don’t have to look too far to find life. In fact, it may be right under our noses, here in this same cosmic corner. Life doesn’t exist on the 7 other planets, but some of the moons surrounding our Jovian neighbors have been garnering interest. Wikipedia has a great article detailing the studies and theories of life on Titan, Saturn’s largest moon. Jupiter’s moon Europa is thought to have an ocean under its icy surface, which could harbor life. Then, there’s Enceladus, whose picture you see above. Like Europa, it is thought to have an ocean. It is also a moon with cryovolcanic activity, with eruptions spewing water, carbon dioxide, carbon monoxide, potassium salts, and other organic materials (Kluger, 2012). With these discoveries, growing numbers within the scientific community consider it a sweet spot for alien life (Lovett, 2011). Much exploration needs to be done, but the excitement over what is known is certainly warranted. And, yes, in the end we may not find anything at all. But, that just means we’ll have to look harder elsewhere.

Or maybe, just maybe, they’ll find us first.

To read more about Enceladus, see:

http://www.time.com/time/health/article/0,8599,2109837,00.html

http://www.nature.com/news/2011/110531/full/news.2011.337.html