I seem like a pretty calm and collected guy, but if you want to see me go on an epic rant, all you have to do is ask me some variation on the question: “why should we bother exploring space when we’ve got problems to fix here on Earth.”
I see this question all the time. All the time, in forums, comments on videos, and from people in audiences.
I think the question is ridiculous on many levels, and I’ve got a bunch of reasons why, but allow me to explain them here.
Before I do, however, I want you to understand that I believe that we human beings are indeed messing up the environment. We’re wiping out species faster than any natural disaster in the history of planet Earth. We’re performing a dangerous experiment on the climate of the planet, increasing temperatures worldwide, with devastating consequences, for both ecosystems and human civilization.
Credit: USFS Gila National Forest (CC BY-SA 2.0)
Unless we get this under control, and there’s no reason to believe we will, we’re going to raise temperatures to levels unseen in millions of years.
There are islands of plastic garbage in the oceans, collected into huge toxic rafts by the currents. Colonies of bees are dying through pesticides and habitat loss.
We’re even polluting the space around the Earth with debris that might tear apart future space missions.
I believe the science, and the science says we’re making a mess.
The first thing is that this whole question is a false dilemma fallacy. Why do we have to choose between space exploration and saving the planet? Why can’t we do both?
NASA’s Orion spacecraft. Credit: NASA
The world spent nearly $750 billion on cigarettes in 2014. NASA’s total budget is less than $20 billion, and Elon Musk thinks he can start sending colonists to Mars for less than $10 billion.
How about the whole world stops smoking, and we spend $20 billion on colonizing Mars and the other $730 billion on renewable fuels and cleaning up our negative impact on the environment, reducing poverty and giving people access to clean water?
Americans spend $27 billion on takeout pizza. Don’t get me wrong, pizza’s great, but I’d be willing to forego pizza if it meant a vibrant and healthy industry of space exploration.
Gambling, lawn care, hood ornaments, weapons of war. Humans spend a lot of money on a lot of things that could be redirected towards both space exploration and reducing our environmental impact.
Number two, it might turn out that space exploration is the best way to save the Earth. I totally agree with Blue Origin’s Jeff Bezos when he says that we already know that Earth is the best place in the Solar System. Let’s keep it that way.
Mars might be a fascinating place to visit and an adventure to colonize, but I want to swim in rivers, climb mountains, walk in forests, watch birds, sail in the ocean.
But the way we’re using up the natural environment will take away from all that. As Bezos says, we should move all the heavy industry off Earth and up into space. Use solar collectors to gather power, mine asteroids for their raw materials. Keep Earth as pristine as possible.
Asteroid mining concept. Credit: NASA/Denise Watt
We won’t know how to do that unless we actually go into space and learn how to survive and run that industry, from space.
Number three, it might be that we’ve already crossed the point of no return. There’s a great science fiction story by Spider Robinson called “In the Olden Days”. It’s about how modern society turned its back on technology, and lost the ability to ever recover.
Humanity used up the entire technology ladder that nature put in front of us; the chunks of iron just sitting on the ground, the oil bubbling out of the Earth, the coal that was easily accessible. Now it takes an offshore drilling rig to get at the oil.
These resources took the Earth millions and even billions of years to accumulate for us to use, and transcend. When the cockroaches evolve intelligence and opposable thumbs, they won’t have those easily accessible resources to jumpstart their own space exploration program.
Number four, as Elon Musk says, we have to protect the cradle of consciousness. Until we find proof otherwise, we have to assume that the Earth is the only place in the Universe that evolved intelligent life.
And until the alien overlords show up and say, “don’t worry humans, we’ve got this,” we have to assume that the responsibility for seeding the life with intelligence rests on us. And we’re one asteroid strike or nuclear apocalypse away from snuffing that out.
I don’t entirely agree that Mars is the best place to do it, but we should at least have another party going on somewhere.
NASA astronaut Ed White during a spacewalk June 3, 1965. In his hand, the Gemini 4 astronaut carries a Hand Held Self Maneuvering Unit (HHSMU) to help him maneuver in microgravity. Credit: NASA
And number five, it’ll be fun. Humans need adventure. We need great challenges to push us to become the best versions of ourselves. We climb mountains because they’re there.
Ask anyone who’s built their own house or tried their hand at homesteading. It’s a tremendous amount of work, but it’s also rewarding in ways that buying stuff just isn’t.
The next time someone uses that argument on you, I hope this gives you some ammunition.
Phew, now I’ll get off my soapbox. Next week, I’m sure we’ll return to poop jokes, obscure science fiction references with a smattering of space science.
Artistic impression of a star going supernova, casting its chemically enriched contents into the universe. Credit: NASA/Swift/Skyworks Digital/Dana Berry
We’ve written quite a few articles on what happens when massive stars fail as supernovae. Here’s a quick recap.
A star with more than 8 times the mass of the Sun runs out of usable fuel in its core and collapses in on itself. The enormous amount of matter falling inward creates a dense remnant, like a neutron star or a black hole. Oh, and an insanely powerful explosion, visible billions of light-years away.
There are a few other classes of supernovae, but that’s the main way they go out.
But it turns out some supernovae just don’t bring their A-game. Instead hitting the ball out of the park, they choke up at the last minute.
They’re failures. They’ll never amount to anything. They’re a complete and utter disappointment to me and your mother. Oh wait, we were talking about stars, right.
So, how does a supernova fail?
In this artist’s conception, a supernova explosion is about to obliterate an orbiting Saturn-like planet. Credit: David A. Aguilar (CfA)
In a regular core collapse supernova, the infalling material pushes the star denser and denser until it reaches the density of 5 billion tons per teaspoon of matter. The black hole forms, and a shockwave ripples outward creating the supernova.
It turns out that the density and energy of the shockwave on its own isn’t enough to actually generate the supernova, and overcome the gravitational force pulling it inward. Instead, it’s believed that neutrinos created at the core pile up behind the shockwave, and give it the push it needs to blast outward into space.
In some cases, though, it’s believed that this additional energy doesn’t show up. Instead of rebounding from the core of the star, the black hole just gobbles it all up. In a fraction of a second, the star is just… gone.
According to astronomers, it might be the case that 1/3rd of all core collapse supernovae die this way, which means that a third of the supergiant stars are just disappearing from the sky. They’re there, and then a moment later, they’re not there.
And this is all that remains. Image Credit: NASA
Seriously, imagine the forces and energy it must take to swallow an entire red supergiant star whole. Black holes are scary.
Astronomers have gone looking for these things, and they’ve actually been pretty tricky to find. It’s like one of those puzzles where you try to figure out what’s missing from a picture. They studied images of galaxies taken by the Hubble Space Telescope, looking for bright supergiant stars which disappeared. In one survey, studying a large group of galaxies, they only turned up a single candidate.
But they only surveyed a handful of galaxies. To really get serious about searching for them, they’ll need better tools, like the Large Synoptic Survey Telescope due for first light in just a few years. This amazing instrument will survey the entire sky every few nights, searching for anything that changes. It’ll find asteroids, comets, variable stars, supernovae, and now, supergiant stars that just disappeared.
We’ve talked about failed supernovae. Now let’s take a few moments and talk about the complete opposite: super successful supernovae.
When a star with more than 8 times the mass of the Sun explodes as a supernova, it leaves behind a remnant. For the lower mass star explosions, they leave behind a neutron star. If it’s a higher mass star, they leave behind a black hole.
But for the largest explosions, where the star had more than 130 times the mass of the Sun, the supernova is so powerful, so complete, there’s no remnant behind. There’s an enormous explosion, and the star is just gone.
No black hole ever forms.
Artist’s impression of a supernova explosion which involves the destruction of a massive supergiant star. Credit: ESO
Astronomers call them pair instability supernovae. In a regular core collapse supernova, the layers of the star collapse inward, producing the highly dense remnant. But in these monster stars, the core is pumping out such energetic gamma radiation that it generates antimatter in the core. The star explodes so quickly, with so much energy, it totally overpowers the gravity pulling it inward.
In a moment, the star is completely and utterly gone, just expanding waves of energy and particles.
Only a few of these supernovae have ever been observed, and they might explain some hypernovae and gamma ray bursts, the most powerful explosions in the Universe.
Beyond 250 times the mass of the Sun, however, gravity takes over again, and you get enormous black holes.
As always, the Universe behaves more strangely than we ever thought possible. Some supernova fail, completely imploding as a black hole. And others detonate entirely, leaving no remnant behind. Trust the Universe to keep mixing it up on us.
Photograph of a Russian technician putting the finishing touches on Sputnik 1, humanity's first artificial satellite. Credit: NASA/Asif A. Siddiqi
Today, people take it for granted that they live in a world that isn’t threatened with imminent nuclear annihilation. A little more than half a century ago, that was the kind of world people lived in, where the United States and Soviet Union were locked in a constant game of one-upmanship that revolved around the development of nuclear weapons.
At the same time, this competition extended to include sports, politics, and the race to reach space. And on October 4th, 1957, the Russians were the first to accomplish this goal with the launch of Sputnik-1, an unmanned research and communications satellite whose appearance ignited the “Space Race” and forever altered the course of history.
Background:
During the early 1950s, the Russians had conducted extensive orbital research using rockets. However, these efforts were limited by the fact that conventional rockets could only achieve orbit for a maximum of a few minutes before falling back to Earth. The next step seemed obvious: placing a research satellite into space that could maintain its orbit and therefore conduct scientific research for an extended period of time.
Sputnik 1 was launched aboard a “Semyorka” rocket, part of the Soviet R7 rocket family. Credit: Wikipedia Commons/Sergei Arssenev
Beginning in March of 1954, Russia’s three top scientists – Mstislav Keldysh, Sergei Korolev and Mikhail Tikhonravov – began discussing the idea of creating an artificial satellite that could be placed into orbit. According to Tikhonravov, such a move would be the next necessary step in the development of rocket technology.
Their efforts received a boost when, on July 29th, 1955, U.S. President Dwight D. Eisinhower announced the US’ intent to launch an artificial satellite during the International Geophysical Year (IGY) – an international scientific project that lasted from July 1st, 1957, to December 31st, 1958.
Because of this, the Soviet Politburo approved of the plans for an artificial satellites and aimed for a launch date that would take place before the beginning of the IGY. The project was approve and the task of creating it was divided between various ministries and the USSR Academy of Sciences.
Keldysh was given control of a commission to oversee develop the “automatic laboratory” aboard the satellite, Tikhonravov and his team of engineers would be responsible for designing the satellite, and Korolev – as head of the Ministry of Defense Industry’s primary design bureau (OKB-1) – would be responsible for building it.
The Sputnik spacecraft stunned the world when it was launched into orbit on Oct. 4th, 1954. Credit: NASA
Design and Construction:
Initially, the Soviet plan for an satellite (known as Object D) was planned to be completed in 1957–58, and called for the creation of a spacecraft that would have a mass of 1,000 – 1,400 kg (2,200 – 3,100 lb) and would carry 200 – 300 kg (440 – 660 lb) of scientific instruments.
In terms of tasks, the mission would seek to measure the density of the atmosphere and its ion composition, solar wind, the Earth’s magnetic field, and cosmic rays (largely for the sake of future missions). A system of ground stations was also called for in order to collect data transmitted from the satellite, as well as observe its orbit and transmit commands.
By the end of 1956, it had become clear that the specifications called for were too ambitious to be accomplished within the established time frame. Fearing the US would launch a satellite before the USSR, Korolev and the OKB-1 suggested that a simpler, lighter satellite could be launched in April-May 1957, before the IGY began.
This satellite would weight about 100 kg (220 lbs) and would forgo heavy scientific instruments in favor of a simple radio transmitter. On February 15th, 1957, the Council of Ministers of the USSR approved this simple satellite, designated “Prosteyshiy Sputnik” – Russian for “Simplest Satellite” – (aka. Object PS), and made arrangements to launch two versions (PS-1 and PS-2) using R-7 rockets.
Exploded view of the Sputnik 1 satellite. Credit: NASA
Launch and Mission:
On October 4th, at 19:28:34 hours Greenwich Mean Time, Sputnik-1 was launched into space from the Baikonur Cosmodrome. The satellite orbited the Earth for three months and emitting radio signals which were monitored by amateur radio operators throughout the world. The signals continued for 22 days until the transmitter batteries ran out on October 26th, 1957.
Before finally burning up during reentry on January 4th, 1958, the satellite traveled a total of about 60 million km (37.28 million mi) and completed 1,440 orbits around the Earth. Sputnik-1 also helped to identify the density of the atmosphere’s upper layer, provided data on radio-signal distribution in the ionosphere, and allowed for the first opportunity for meteoroid detection.
Impact:
Apart from its value as a technological first, Sputnik also had the effect of expediting both Soviet and American efforts to explore space. News of the launch triggered a great deal of fear in the United States, as many worried that Sputnik could represent a threat to national security, not to mention America’s technological leadership.
As a result, Congress urged then-President Dwight D. Eisenhower to take immediate action, which resulted in the signing of the National Aeronautics and Space Act on July 29th, 1958, officially establishing NASA. Immediately, NASA became dedicated to researching hypersonic flight and taking the necessary steps towards creating crewed spacecraft.
Yury Gagarin before a space flight aboard the Vostok spacecraft. April 12, 1961 Credit: RIA Novosti
The Soviets did the same, taking drastic steps towards the creation of rockets and crew capsules as part of the Vostok Program. This would culminate in the first man being launched into orbit space – cosmonaut Yuri Gagarin – on April 12th, 1961. The pace of this competition would continue until July 20th, 1969, when the US made the historic first of landing astronauts on the Moon.
Decades later, Sputnik-1 is still viewed as a groundbreaking achievement. Despite its diminutive size and simplicity, its launch was a major breakthrough for the Soviets, and caused no shortage of fear and consternation in the west. In many ways, we are lucky to be living in an age where cooperation has taken the place of competition. Today, such breakthroughs are the result of a world coming together, and not enmity between nations.
Whirlpool Galaxy M51 (NGC 5194). Credit: Hubble Heritage Team (STScI/AURA)
N. Scoville (Caltech)
On a clear night, you can make out the band of the Milky Way in the night sky. For millennia, astronomers looked upon it in awe, slowly coming to the realization that our Sun was merely one of billions of stars in the galaxy. Over time, as our instruments and methods improved, we came to realize that the Milky Way itself was merely one of billions of galaxies that make up the Universe.
Thanks to the discovery of Relativity and the speed of light, we have also come to understand that when we look through space, we are also looking back in time. By seeing an object 1 billion light-years away, we are also seeing how that object looked 1 billion years ago. This “time machine” effect has allowed astronomers to study how galaxies came to be (i.e. galactic evolution).
The process in which galaxies form and evolve is characterized by steady growth over time, which began shortly after the Big Bang. This process, and the eventual fate of galaxies, remain the subject of intense fascination, and is still fraught with its share of mysteries.
Illustration of the depth by which Hubble imaged galaxies in prior Deep Field initiatives, in units of the Age of the Universe. Credit: NASA and A. Feild (STScI)
Galaxy Formation:
The current scientific consensus is that all matter in the Universe was created roughly 13.8 billion years ago during an event known as the Big Bang. At this time, all matter was compacted into a very small ball with infinite density and intense heat called a Singularity. Suddenly, the Singularity began expanding, and the Universe as we know it began.
After rapidly expanding and cooling, all matter was almost uniform in distribution. Over the course of the several billion years that followed, the slightly denser regions of the Universe began to become gravitationally attracted to each other. They therefore grew even denser, forming gas clouds and large clumps of matter.
These clumps became primordial galaxies, as the clouds of hydrogen gas within the proto-galaxies underwent gravitational collapse to become the first stars. Some of these early objects were small, and became tiny dwarf galaxies, while others were much larger and became the familiar spiral shapes, like our own Milky Way.
Galactic Mergers:
Once formed, these galaxies evolved together in larger galactic structures called groups, clusters and superclusters. Over time, galaxies were attracted to one another by the force of their gravity, and collided together in a series of mergers. The outcome of these mergers depends on the mass of the galaxies in the collision.
Small galaxies are torn apart by larger galaxies and added to the mass of larger galaxies. Our own Milky Way recently devoured a few dwarf galaxies, turning them into streams of stars that orbit the galactic core. But when large galaxies of similar size come together, they become giant elliptical galaxies.
When this happens, the delicate spiral structure is lost, and the merged galaxies become large and elliptical. Elliptical galaxies are some of the largest galaxies ever observed. Another consequence of these mergers is that the supermassive black holes (SMBH) at their centers become even larger.
Not all mergers will result in elliptical galaxies, mind you. But all mergers result in a change in the structure of the merged galaxies. For example, it is believed that the Milky Way is experiencing a minor merger event with the nearby Magellanic Clouds; and in recent years, it has been determined that the Canis Major dwarf galaxy has merged with our own.
While mergers are seen as violent events, actual collisions are not expected to happen between star systems, given the vast distances between stars. However, mergers can result in gravitational shock waves, which are capable of triggering the formation of new stars. This is what is predicted to happen when our own Milky Way galaxy merges with the Andromeda galaxy in about 4 billion years time.
Galactic Death:
Ultimately, galaxies cease forming stars once they deplete their supply of cold gas and dust. As the supply runs out, star forming slows over the course of billions of years until it ceases entirely. However, ongoing mergers will ensure that fresh stars, gas and dust are deposited in older galaxies, thus prolonging their lives.
At present, it is believed that our galaxy has used up most of its hydrogen, and star formation will slow down until the supply is depleted. Stars like our Sun can only last for 10 billion years or so; but the smallest, coolest red dwarfs can last for a few trillion years. However, thanks to the presence of dwarf galaxies and our impending merger with Andromeda, our galaxy could exist even longer.
However, all galaxies in this vicinity of the Universe will eventually become gravitationally bound to each other and merge into a giant elliptical galaxy. Astronomers have seen examples of these sorts of “fossil galaxies”, a good of which is Messier 49 – a supermassive elliptical galaxy.
These galaxies have used up all their reserves of star forming gas, and all that’s left are the longer lasting stars. Eventually, over vast lengths of time, those stars will wink out one after the other, until the whole thing is the background temperature of the Universe.
After our galaxy merges with Andromeda, and goes on to merge with all other nearby galaxies in the local group, we can expect that it too will undergo a similar fate. And so, galaxy evolution has been occurring over billions of years, and it will continue to happen for the foreseeable future.
Astronauts need spacesuits to survive the temperature of the Moon. Image credit: NASA
Have you ever heard that it’s possible to buy property on the Moon? Perhaps someone has told you that, thanks to certain loopholes in the legal code, it is possible to purchase your very own parcel of lunar land. And in truth, many celebrities have reportedly bought into this scheme, hoping to snatch up their share of land before private companies or nations do.
Despite the fact that there may be several companies willing to oblige you, the reality is that international treaties say that no nation owns the Moon. These treaties also establish that the Moon is there for the good of all humans, and so it’s impossible for any state to own any lunar land. But does that mean private ownership is impossible too? The short answer is yes.
The long answer is, it’s complicated. At present, there are multiple nations hoping to build outposts and settlements on the Moon in the coming decades. The ESA hopes to build a “international village” between 2020 and 2030 and NASA has plans for its own for a Moon base.
The ESA recently elaborated its plan to create a Moon base by the 2030s. Credit: ESA/Foster + Partners
Because of this, a lot of attention has been focused lately on the existing legal framework for the Moon and other celestial bodies. Let’s take a look at the history of “space law”, shall we?
Outer Space Treaty:
On Jan. 27th, 1967, the United States, United Kingdom, and the Soviet Union sat down together to work out a treaty on the exploration and use of outer space. With the Soviets and Americans locked in the Space Race, there was fear on all sides that any power that managed to put resources into orbit, or get to the Moon first, might have an edge on the others – and use these resources for evil!
Astronaut Charles M. Duke Jr. shown collecting samples on the lunar surface with the Lunar Roving Vehicle during the Apollo 16 mission. Credit: NASA
The treaty is overseen the United Nations Office for Outer Space Affairs (UNOOSA). It’s a big document, with lots of articles, subsections, and legalese. But the most relevant clause is Article II of the treaty, where it states:
“Outer space, including the moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.”
“Loophole” in the Treaty:
Despite clearly saying that Outer Space is the property of all humanity, and can only be used for the good of all, the language is specific to national ownership. As a result, there is no legal consensus on whether or not the treaty’s prohibition are also valid as far as private appropriation is concerned.
However, Article II addresses only the issue of national ownership, and contains no specific language about the rights of private individuals or bodies in owning anything in outer space. Because of this, there are some who have argued that property rights should be recognized on the basis of jurisdiction rather than territorial sovereignty.
About 20 minutes after the first step, Aldrin joined Armstrong on the surface and became the second human to set foot on the Moon. Credit: NASA
Looking to Article VI though, it states that governments are responsible for the actions of any party therein. So it is clear that the spirit of the treaty is meant to apply to all entities, be they public or private. As it states:
“States Parties to the Treaty shall bear international responsibility for national activities in outer space, including the moon and other celestial bodies, whether such activities are carried on by governmental agencies or by non-governmental entities, and for assuring that national activities are carried out in conformity with the provisions set forth in the present Treaty. The activities of non-governmental entities in outer space, including the moon and other celestial bodies, shall require authorization and continuing supervision by the appropriate State Party to the Treaty.”
In other words, any person, organization or company operating in space is answerable to their respective government. But since no specific mention is made of private ownership, there are those who claim that this represents a “loophole” in the treaty which allows them to claim and sell land on the Moon at this time. Because of this ambiguity, there have been attempts to augment the Outer Space Treaty.
The Moon Treaty:
On Dec. 18th, 1979, members of the United Nations presented an agreement which was meant to be a follow-up to the Outer Space Treaty and close its supposed loopholes. Known as the “Agreement Governing the Activities of States on the Moon and Other Celestial Bodies” – aka. “The Moon Treaty” or “Moon Agreement” – this treaty intended to establish a legal framework for the use of the Moon and other celestial bodies.
Buzz Aldrin’s panorama of the Apollo 11 landing site is the only good picture of mission commander Neil Armstrong on the lunar surface. Credit: NASA
Much like the Outer Space Treaty, the agreement established that the Moon should be used for the benefit of all humanity and not for the sake of any individual state. The treaty banned weapons testing, declared that any scientific research must be open and shared with the international community, and that nations and individuals and organizations could not claim anything.
In practice, the treaty failed because it has not been ratified by any state that engages in crewed space exploration or has domestic launch capability. This includes the United States, the larger members of the ESA, Russia, China, Japan and India. Though it expressly forbids both national and private ownership of land on the Moon, or the use thereof for non-scientific, non-universal purposes, the treaty effectively has no teeth.
Bottom line, there is nothing that expressly forbids companies from owning land on the Moon. However, with no way to claim that land, anyone attempting to sell land to prospective buyers is basically selling snake oil. Any documentation that claims you own land on the Moon is unenforceable, and no nation on the planet that has signed either the Outer Space Treaty or the Moon Treaty will recognize it.
The annotated features on the lunar nearside. You’ll notice, not one of them says “Land for Sale!” Credit: Wikimedia Commons/ Peter Freiman(Cmglee). Background photograph by Gregory H. Revera.
Then again, if you were able to fly up to the Moon and build a settlement there, it would be pretty difficult for anyone to stop you. But don’t expect that to the be the last word on the issue. With multiple space agencies looking to create “international villages” and companies hoping to create a tourist industry, you could expect some serious legal battles down the road!
But of course, this is all academic. With no atmosphere to speak of, temperatures reaching incredible highs and lows – ranging from 100 °C (212 °F) to -173 °C (-279.4 °F) – its low gravity (16.5 % that of Earth), and all that harsh Moon dust, nobody outside of trained astronauts (or the clinically insane) should want to spend a significant amount of time there!
If you’ve seen at least one other episode of the Guide to Space, you know I’m obsessed about the Fermi Paradox. This idea that the Universe is big and old, and should be teeming with life. And yet, we have no evidence that it exists out there. We wonder, where are all the aliens?
Ah well, maybe we’re in a cosmic zoo, or maybe the Universe is just too big, or the laws of physics prevent any kind of meaningful travel or communications. Fine. I doubt it, but fine.
A picture of Earth taken by Apollo 11 astronauts. Credit: NASA
The moment that the Apollo-11 mission touched down on the Moon, followed by Neil Armstrong‘s famous words – “That’s one small step for [a] man, one giant leap for mankind” – is one of the most iconic moments in history. The culmination of years of hard work and sacrifice, it was an achievement that forever established humanity as a space-faring species.
And in the year’s that followed, several more spacecraft and astronauts landed on the Moon. But before, during and after these missions, a number of other “lunar landings” were accomplished as well. Aside from astronauts, a number of robotic missions were mounted which were milestones in themselves. So exactly what were the earliest lunar landings?
Robotic Missions:
The first missions to the Moon consisted of probes and landers, the purpose of which was to study the lunar surface and determine where crewed missions might land. This took place during the 1950s where both the Soviet Space program and NASA sent landers to the Moon as part of their Luna and Pioneer programs.
The Soviet Luna 2 probe, the first man-made object to land on the Moon. Credit: NASA
After several attempts on both sides, the Soviets managed to achieve a successful lunar landing on Sept. 14th, 1959 with their Luna-2 spacecraft. After flying directly to the Moon for 36 hours, the spacecraft achieved a hard landing (i.e. crashed) on the surface west of the Mare Serenitatis – near the craters Aristides, Archimedes, and Autolycus.
The primary objective of the probe was to help confirm the discovery of the solar wind, turned up by the Luna-1mission. However, with this crash landing, it became the first man-made object to touch down on the Moon. Upon impact, it scattered a series of Soviet emblems and ribbons that had been assembled into spheres, and which broke apart upon hitting the surface.
The next craft to make a lunar landing was the Soviet Luna-3 probe, almost a month after Luna-2 did. However, unlike its predecessor, the Luna-3 probe was equipped with a camera and managed to send back the first images of the far side of the Moon.
The first US spacecraft to impact the Moon was the Ranger-7 probe, which crashed into the Moon on July 31st, 1964. This came after a string of failures with previous spacecraft in the Pioneer and Ranger line of robotic spacecraft. Prior to impact, it too transmitted back photographs of the Lunar surface.
The Ranger 7 lander, which became the first US spacecraft to land on the Moon. Credit: NASA
This was followed by the Ranger-8 lander, which impacted the surface of the Moon on Feb. 20th, 1965. The spacecraft took 7,000 high-resolution images of the Moon before crashing onto the surface, just 24 km from the Sea of Tranquility, which NASA had been surveying for the sake of their future Apollo missions. These images, which yielded details about the local terrain, helped to pave the way for crewed missions.
The first spacecraft to make a soft landing on the Moon was the Soviet Luna-9 mission, on February 3rd, 1966. This was accomplished through the use of an airbag system that allowed the probe to survive hitting the surface at a speed of 50 km/hour. It also became the first spacecraft to transmit photographic data back to Earth from the surface of another celestial body.
The first truly soft landing was made by the US with the Surveyor-1 spacecraft, which touched down on the surface of the Moon on June 2nd, 1966. After landing in the Ocean of Storms, the probe transmitted data back to Earth that would also prove useful for the eventual Apollo missions.
Several more Surveyor missions and one more Luna mission landed on the Moon before crewed mission began, as part of NASA’s Apollo program.
Launch of Apollo 11 mission aboard a Saturn V rocket on July 16th, 1969. Credit: NASA
Crewed Missions:
The first crewed landing on the Moon was none other than the historic Apollo-11 mission, which touched down on the lunar surface on July 20th, 1969. After achieving orbit around the Moon in their Command Module (aka. the Columbia module), Neil Armstrong and Buzz Aldrin rode the Lunar Excursion (Eagle) Module down to the surface of the Moon.
Once they had landed, Armstrong radioed to Mission Control and announced their arrival by saying: “Houston, Tranquility Base here. The Eagle has landed.” Once the crew had gone through their checklist and depressurized the cabin, the Eagles’ hatch was opened and Armstrong began walking down the ladder to the Lunar surface first.
When he reached the bottom of the ladder, Armstrong said: “I’m going to step off the LEM now” (referring to the Lunar Excursion Module). He then turned and set his left boot on the surface of the Moon at 2:56 UTC July 21st, 1969, and spoke the famous words “That’s one small step for [a] man, one giant leap for mankind.”
About 20 minutes after the first step, Aldrin joined Armstrong on the surface and became the second human to set foot on the Moon. The two then unveiled a plaque commemorating their flight, set up the Early Apollo Scientific Experiment Package, and planted the flag of the United States before blasting off in the Lunar Module.
Buzz Aldrin on the Moon during the Apollo 11 mission, with the reflection of Neil Armstrong visible in his face plate. Credit: NASA
Several more Apollo missions followed which expanded on the accomplishments of the Apollo-11 crew. The US and NASA would remain the only nation and space agency to successfully land astronauts on the Moon, an accomplishment that has not been matched to this day.
Today, multiple space agencies (and even private companies) are contemplating returning to the Moon. Between NASA, the European Space Agency (ESA), the Russian Space Agency (Roscosmos), and the Chinese National Space Administration (CNSA), there are several plans for crewed missions, and even the construction of permanent bases on the Moon.
NASA astronauts exploring Mars on future missions starting perhaps in the 2030’s will require protection from long term exposure to the cancer causing space radiation environment. Credit: NASA.
History was made on July 20th, 1969, when Apollo 11 astronauts Neil Armstrong and Buzz Aldrin set foot on the surface of the Moon. The moment was the culmination of decades of hard work, research, development and sacrifice. And since that time, human beings have been waiting and wondering when we might achieve the next great astronomical milestone.
So really, when will we see a man or woman set foot on Mars? The prospect has been talked about for decades, back when NASA and the Soviets were still planning on setting foot on the Moon. It is the next logical step, after all. And at present, several plans are in development that could be coming to fruition in just a few decades time.
Original Proposals:
Werner Von Braun, the (in)famous former Nazi rocket scientist – and the man who helped spearhead NASA’s Project Mercury – was actually the first to develop a concept for a crewed mission to Mars. Titled The Mars Project (1952), his proposal called for ten spacecraft (7 passenger, 3 cargo) that would transport a crew of 70 astronauts to Mars.
In between launching V-2s in New Mexico and developing rockets at Redstone Arsenal, Von Braun had time to write Mars Projekt (1952). Credit: Mars Project, Von Braun
His proposal was based in part on the large Antarctic expedition known as Operation Highjump (1946–1947), a US Navy program which took place a few years before he started penning his treatise. The plan called for the construction of the interplanetary spacecraft in around the Earth using a series of reusable space shuttles.
He also believed that, given the current pace of space exploration, such a mission could be mounted by 1965 (later revised to 1980) and would spend the next three years making the round trip mission. Once in Mars orbit, the crew would use telescopes to find a suitable site for their base camp near the equator.
A landing crew would then descend using a series of detachable winged aircraft (with ski landing struts) and glide down to land on the polar ice caps. A skeleton crew would remain with the ships in orbit as the surface crew would then travel 6,500 km overland using crawlers to the identified base camp site.
They would then build a landing strip which would allow the rest of the crew to descend from orbit in wheeled gliders. After spending a total of 443 days on Mars conducting surveys and research, the crew would use these same gliders as ascent craft to return to the mother ships.
Astronaut Eugene A. Cernan during the Apollo 17 mission, December 11th, 1972, shown conducting a checkout of the Lunar Roving Vehicle (LRV). Credit: NASA
Von Braun not only calculated the size and weight of each ship, but also how much fuel each would require for the round trip. He also computed the rocket burns necessary to perform the required maneuvers. Because of the detailed nature, calculations and planning in his proposal, The Mars Project remains one of the most influential books on human missions to the Red Planet.
Obviously, such a mission didn’t happen by 1965 (or 1980 for that matter). In fact, humans didn’t even return to the Moon after Eugene Cernan climbed out of the Apollo 17 capsule in 1972. With the winding down of the Space Race and the costs of sending astronauts to the Moon, plans to explore Mars were placed on the backburner until the last decade of the 20th century.
In 1990, a proposal called Mars Direct was developed by Robert Zubrin, founder of the Mars Society and fellow aerospace engineer David Baker. This plan envisioned a series of cost-effective mission to Mars using current technology, with the ultimate goal of colonization.
The initial missions would involve crews landing on the surface and leaving behind hab-structures, thus making subsequent missions easier to undertake. In time, the surface habs would give way to subsurface pressurized habitats built from locally-produced Martian brick. This would represent a first step in the development of in-situ resource utilization, and eventual human settlement.
Artist’s rendering Manned Habitat Units and Mars vehicles, part of the Mars Design Reference Mission 3.0. Credit: NASA
During and after this initial phase of habitat construction, hard-plastic radiation- and abrasion-resistant geodesic domes would be deployed to the surface for eventual habitation and crop growth. Local industries would begin to grow using indigenous resources, which would center around the manufacture of plastics, ceramics and glass out of Martian soil, sand and hydrocarbons.
While Zubrin acknowledged that Martian colonists would be partially Earth-dependent for centuries, he also stated that a Mars colony would also be able to create a viable economy. For one, Mars has large concentrations of precious metals that have not been subjected to millennia of human extracting. Second, the concentration of deuterium – a possible source for rocket fuel and nuclear fusion – is five times greater on Mars.
In 1993, NASA adopted a version of this plan for their “Mars Design Reference” mission, which went through five iterations between 1993 and 2009. And while it involved a great deal of thinking and planning, it failed to come up with any specific hardware or projects.
Current Proposals:
Things changed in the 21st century after two presidential administrations made fateful decisions regarding NASA. The first came in 2004 when President George W. Bush announced the “Vision for Space Exploration“. This involved retiring the Space Shuttle and developing a new class of launchers that could take humans back to the Moon by 2020 – known as the Constellation Program.
Then, in February of 2010, the Obama administration announced that it was cancelling the Constellation Program and passed the Authorization Act of 2010. Intrinsic to this plan was a Mars Direct mission concept, which called for the development of the necessary equipment and systems to mount a crewed mission to Mars by the 2030s.
In 2015, NASA’s Human Exploration and Operations Mission Directorate (HEOMD) presented the “Evolvable Mars Campaign”, which outlined their plans for their “Journey to Mars’ by the 2030s. Intrinsic to this plan was the use of the new Orion Multi-Purpose Crew Vehicle (MPCV) and the Space Launch System (SLS).
The proposed journey would involve Three Phases, which would involve a total of 32 SLS launches between 2018 and the 2030s. These missions would send all the necessary components to cis-lunar space and then onto near-Mars space before making crewed landings onto the surface.
Phase One (the “Earth Reliant Phase”) calls for long-term studies aboard the ISS until 2024, as well as testing the SLS and Orion Crew capsule. Currently, this involves the planned launch of Exploration Mission 1 (EM-1) in Sept. of 2018, which will be the first flight of the SLS and the second uncrewed test flight of the Orion spacecraft.
NASA’s Journey to Mars. NASA is developing the capabilities needed to send humans to an asteroid by 2025 and Mars in the 2030s. Credit: NASA/JPL
NASA also plans to capture a near=Earth asteroid and bring it into lunar orbit, as a means of testing the capabilities and equipment for a Mars mission. Known as the Asteroid Redirect Mission, this mission is scheduled to take place in the 2020s and would primarily involve a robotic mission towing the asteroid and returning samples.
Exploration Mission 2 (EM-2), the first crewed flight using the Orion capsule, would conduct a flyby around the Moon and this asteroid between 2021 and 2023. At this point, NASA would be moving into Phase Two (“Proving Ground”) of the Journey to Mars, where the focus would move away from Earth and into cis-lunar space.
Multiple SLS launches would deliver the mission components during this time – including a habitat that would eventually be transported to Martian orbit, landing craft, and exploration vehicles for the surface of Mars. This phase also calls for the testing of key technologies, like Solar Electric Propulsion (aka. the ion engine).
By the early 2030s, Phase Three (“Earth Independent”) would begin. This calls for testing the entry, descent and landing techniques needed to get to the Martian surface, and the development of in-situ resource utilization. It also calls for the transferring of all mission components (and an exploration crew) to Martian orbit, from which the crews would eventually mount missions to designated “Exploration Zones” on the surface.
The European Space Agency (ESA) has long-term plans to send humans to Mars, though they have yet to build a manned spacecraft. As part of the Aurora Program, this would involve a crewed mission to Mars in the 2030s using an Ariane M rocket. Other key points along that timeline include the ExoMars rover (2016-2020), a crewed mission to the Moon in 2024, and an automated mission to Mars in 2026.
Roscosmos, the Russian Federal Space Agency, is also planning a crewed mission to Mars, but doesn’t envision it happening until between 2040 and 2060. In the meantime, they have conducted simulations (called Mars-500), which wrapped up in Russia back in 2011. The Chinese space agency similarly has plans to mount a crewed mission to Mars between 2040 and 2060, but only after crewed missions to Mars take place.
In 2012, a group of Dutch entrepreneurs revealed plans for a crowdfunded campaign to establish a human Mars base, beginning in 2023. Known as MarsOne, the plan calls for a series of one-way missions to establish a permanent and expanding colony on Mars, which would be financed with the help of media participation.
Other details of the MarsOne plan include sending a telecom orbiter by 2018, a rover in 2020, and the base components and its settlers by 2023. The base would be powered by 3,000 square meters of solar panels and the SpaceX Falcon 9 Heavy rocket would be used to launch the hardware. The first crew of 4 astronauts would land on Mars in 2025; then, every two years, a new crew of 4 astronauts would arrive.
SpaceX and Tesla CEO Elon Musk has also announced plans to establish a colony on Mars in the coming decades. Intrinsic to this plan is the development of the Mars Colonial Transporter (MCT), a spaceflight system that would rely of reusable rocket engines, launch vehicles and space capsules to transport humans to Mars and return to Earth.
As of 2014, SpaceX has begun development of the large Raptor rocket engine for the Mars Colonial Transporter, and a successful test was announced in September of 2016. In January 2015, Musk said that he hoped to release details of the “completely new architecture” for the Mars transport system in late 2015.
In June 2016, Musk stated in the first unmanned flight of the MCT spacecraft would take place in 2022, followed by the first manned MCT Mars flight departing in 2024. In September 2016, during the 2016 International Astronautical Congress, Musk revealed further details of his plan, which included the design for an Interplanetary Transport System (ITS) – an upgraded version of the MCT.
According to Musk’s estimates, the ITS would cost $10 billion to develop and would be ready to ferry the first passengers to Mars as early as 2024. Each of the SpaceX vehicles would accommodate 100 passengers, with trips being made every 26 months (when Earth and Mars are closest). Musk also estimated that tickets would cost $500,000 per person, but would later drop to a third of that.
And while some people might have a hard time thinking of MarsOne’s volunteers or SpaceX’s passengers as astronauts, they would nevertheless be human beings setting foot on the Red Planet. And if they should make it there before any crewed missions by a federal space agency, are we really going to split hairs?
So the question remains, when will see people sent to Mars? The answer is, assuming all goes well, sometime in the next two decades. And while there are plenty who doubt the legitimacy of recent proposals, or the timetables they include, the fact that we are speaking about going to Mars a very real possibility shows just how far we’ve come since the Apollo era.
And does anyone need to be reminded that there were plenty of doubts during the “Race to the Moon” as well? At the time, there were plenty of people claiming the resources could be better spent elsewhere and those who doubted it could even be done. Once again, it seems that the late and great John F. Kennedy should have the last word on that:
“We choose to go to the Moon! … We choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard; because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one we intend to win.”
If you’d like more information about humans traveling to Mars, check out the Mars Society’s homepage. And here’s a link to MarsDrive, and another group looking to send people to Mars.
M24 (the Small Sagittarius Cloud) and nearby Messier Objects. Credit: Wikisky
Welcome back to Messier Monday! In our ongoing tribute to the great Tammy Plotner, we take a look at the Messier 24 star cloud. Enjoy!
Back in the 18th century, famed French astronomer Charles Messier noted the presence of several “nebulous objects” in the night sky. Having originally mistaken them for comets, he began compiling a list of these objects so that other astronomers wouldn’t make the same mistake. Consisting of 100 objects, the Messier Catalog has come to be viewed as a major milestone in the study of Deep Space Objects.
One such object is Messier 24, otherwise known as the Sagittarius Star Cloud (or Delle Caustiche). Located in the Sagittarius constellation, located approximately 100,000 light years from Earth, this cluster of the Milky Way is one of the densest concentration of individual stars in the night sky.
Description:
Messier 24 is one of the most curious of the catalog entries because it really isn’t a star cluster – simply an oddity. What we are looking at is thousands of stars that belong to the Sagittarius arm of the Milky Way galaxy seen through a chance hole in the gas and dust… a clear “window” in space.
Messier 24 (Sagittarius Star Cloud, Delle Caustiche), also showing like the dark nebula Barnard 92, the dark nebula Barnard 93, and the open cluster NGC 6603. Credit: Wikipedia Commons/Tomasmazon
And speaking of space, M24 fills a space of significant volume, to a depth of 10,000 to 16,000 light-years. This makes it the most dense concentration of individual stars visible using binoculars, with around 1,000 stars visible within a single field of view!
Still, it is sometimes referred to as the Small Sagittarius Star Cloud in order to differentiate it from the Great Sagittarius Star Cloud located north of Gamma Sagittarii and Delta Sagittarii. When viewing this awesome area, take into account how many different objects you can spot just within this region – like dim open cluster, NGC 6603.
E.E. Barnard has cataloged two dark nebulae in the northern region as objects 92 and 93. How about lesser known clusters like Collinder 469 and Markarian 38? Along the southern edge you’ll find emission nebula IC 1283-1284, with two adjacent reflection nebulae, NGC 6589 and NGC 6590.
Their fueling source is the notable little open cluster NGC 6595. Take a tour on the western edge of M24 and see if you can spot 12th-magnitude planetary nebula NGC 6567. Need more? Then how about Delta Cephei variable WZ Sagittarii in the southern area. Its a pulsating giant star that varies in brightness between magnitude 7.5 and 8.5 in slightly less than 22 days!
The Sagittarius constellation. Credit: iau.org
History of Observation:
As bright as the Sagittarius Star Cloud is, we know that Messier probably wasn’t the first to see it – but he was the first to catalog it. As he wrote about it in his notes:
“In the same night, June 20 to 21, 1764, I have discovered on the same parallel as the star cluster I have just been talking about and near the extremity of the bow of Sagittarius, in the milky way, a considerable nebulosity, of about one degree and a half extension: in that nebulosity there are several stars of different magnitudes; the light which is between these stars is divided in several parts. I have determined approximately the position of the middle of this cloud of light; its right ascension is 270d 26′, and its declination 18d 26′, south.”
While other historic astronomers would also look at Messier’s “discovery”, they realized they were looking at a portion of the Milky Way and were somewhat less than enthusiastic. The Sagittarius Star Cloud was named “Delle Caustiche” by Fr. Secchi, “from the peculiar arrangement of its stars in rays, arches, caustic curves, and intertwined spirals.”
As is often the case with Messier Objects, it was the late Admiral Smyth who described it with flowering prose. As he wrote of the large star cloud in July of 1835:
“A beautiful field of stars, below the sinister base of the Polish shield, and in a richly clustering portion of the Milky Way. This object was discovered by Messier in 1764, and described as a mass of stars — a great nebulosity of which the light is divided in several parts. This was probably owing to want of power in the instruments used, as the whole is fairly resolvable, though there is a gathering spot with much star dust [This is NGC 6603!].”
M24, located in the direction of the Sagittarius constellation, shares that region of the sky with many Deep Sky Objects. Credit: freestarcharts.com
Locating Messier 24:
From a dark sky location, M24 is easily located with the unaided eye. It will appear as a large hazy patch in northern portion of the constellation of Sagittarius, about a handspan above the teapot-shaped Sagittarius asterism. For those observing under urban skies, even the slightest optical aid will easily reveal this massive cloud of stars.
Spanning a degree and a half of sky means this huge object is going to cover anywhere from about 1/3 to 1/2 the field of view in most binoculars. It can easily be seen in all optical finderscopes and requires minimum magnification in all telescopes. Even then, you’ll only be able to study portions of the Sagittarius Star Cloud at a time. given its sheer size.
So go forth, and gather ye some star dust of your own. There’s plenty for everyone!
And here are the quick facts on the Sagittarius Stat Cloud to help you get started:
Object Name: Messier 24 Alternative Designations: M24, IC 4715, Sagittarius Star Cloud, Delle Caustiche Object Type: Star Cloud – contains Open Cluster NGC 6603 and NGC 6595, Barnard 92, Barnard 93, Collinder 469, IC 1283-1284, NGC 6589/90 and planetary nebula NGC 6567 Constellation: Sagittarius Right Ascension: 18 : 16.9 (h:m) Declination: -18 : 29 (deg:m) Distance: 10.0 (kly) Visual Brightness: 4.6 (mag) Apparent Dimension: 90 (arc min)
NanoRacks CubeSats photographed after deployment from the ISS by an Expedition 38 crew member. Credit: NASA
One of the defining characteristics of the modern era of space exploration is the open nature of it. In the past, space was a frontier that was accessible only to two federal space agencies – NASA and the Soviet space program. But thanks to the emergence of new technologies and cost-cutting measures, the private sector is now capable of providing their own launch services.
In addition, academic institutions and small countries are now capable of building their own satellites for the purposes of conducting atmospheric research, making observations of Earth, and testing new space technologies. It’s what is known as the CubeSat, a miniaturized satellite that is allowing for cost-effective space research.
Structure and Design:
Also known as nanosatellites, CubeSats are built to standard dimensions of 10 x 10 x 11 cm (1 U) and are shaped like cubes (hence the name). They are scalable, coming in versions that measure 1U, 2Us, 3Us, or 6Us on a side, and typically weigh less than 1.33 kg (3 lbs) per U. CubSats of 3Us or more are the largest, being composed of three units stacked lengthwise with a cylinder encasing them all.
A cubesat structure, 1U in size, without the outer skin. Credit: Wikipedia Commons/Svobodat
In recent years larger CubeSat platforms have been proposed, which include a 12U model (20 x 20 x 30 cm or 24 x 24 x 36 cm), that would extend the capabilities of CubeSats beyond academic research and testing new technologies, incorporating more complex science and national defense goals.
The main reason for miniaturizing satellites is to reduce the cost of deployment, and because they can be deployed in the excess capacity of a launch vehicle. This reduces the risks associated with missions where additional cargo has to be piggybacked to the launcher, and also allows for cargo changes on short notice.
They can also be made using commercial off-the-shelf (COTS) electronics components, which makes them comparably easy to create. Since CubeSats missions are often made to very Low Earth Orbits (LEO), and experience atmospheric reentry after just days or weeks, radiation can largely be ignored and standard consumer-grade electronics may be used.
CubeSats are built from four specific types of aluminum alloy to ensure that they have the same coefficient of thermal expansion as the launch vehicle. The satellites are also coated with a protective oxide layer along any surface that comes into contact with the launch vehicle to prevent them from being cold welded into place by extreme stress.
Components:
CubeSats often carry multiple on-board computers for the sake of carrying out research, as well providing for attitude control, thrusters, and communications. Typically, other on-board computers are included to ensure that the main computer is not overburdened by multiple data streams, but all other on-board computers must be capable of interfacing with it.
An example of a 3U cubesat – 3 1U cubes stacked. This cubesat size could function as the telescope of a two cubesat telescope system. It could be a simple 10 cm diameter optic system or use fancier folding optics to improve its resolving power. Credit: LLNL
Typically, a primary computer is responsible for delegating tasks to other computers – such as attitude control, calculations for orbital maneuvers, and scheduling tasks. Still, the primary computer may be used for payload-related tasks, like image processing, data analysis, and data compression.
Miniaturized components provide attitude control, usually consisting of reaction wheels, magnetorquers, thrusters, star trackers, Sun and Earth sensors, angular rate sensors, and GPS receivers and antennas. Many of these systems are often used in combination in order to compensate for shortcomings, and to provide levels of redundancy.
Sun and star sensors are used to provide directional pointing, while sensing the Earth and its horizon is essential for conducting Earth and atmospheric studies. Sun sensors are also useful in ensuring that the CubsSat is able to maximize its access to solar energy, which is the primary means of powering a CubeSat – where solar panels are incorporated into the satellites outer casing.
Meanwhile, propulsion can come in a number of forms, all of which involve miniaturized thrusters providing small amounts of specific impulse. Satellites are also subject to radiative heating from the Sun, Earth, and reflected sunlight, not to mention the heat generated by their components.
Will cubesats develop a new technological branch of astronomy? Goddard engineers are taking the necessary steps to make cubesat sized telescopes a reality. (Credit: NASA, UniverseToday/TRR)
As such, CubeSat’s also come with insulation layers and heaters to ensure that their components do not exceed their temperature ranges, and that excess heat can be dissipated. Temperature sensors are often included to monitor for dangerous temperature increases or drops.
For communications, CubeSat’s can rely on antennae that work in the VHF, UHF, or L-, S-, C- and X-bands. These are mostly limited to 2W of power due to the CubeSat’s small size and limited capacity. They can be helical, dipole, or monodirection monopole antennas, though more sophisticated models are being developed.
Propulsion:
CubeSats rely on many different methods of propulsion, which has in turn led to advancements in many technologies. The most common methods includes cold gas, chemical, electrical propulsion, and solar sails. A cold gas thruster relies on inert gas (like nitrogen) which is stored in a tank and released through a nozzle to generate thrust.
As propulsion methods go, it is the simplest and most useful system a CubeSat can use. It is also one of the safest too, since most cold gases are neither volatile nor corrosive. However, they have limited performance and cannot achieve high impulse maneuvers. Hence why they are generally used in attitude control systems, and not as main thrusters.
Miniaturized ion engines are a method of choice for providing thrust control for CubeSats. Credits: NASA
Chemical propulsion systems rely on chemical reactions to produce high-pressure, high-temperature gas which is then directed through a nozzle to create thrust. They can be liquid, solid, or a hybrid, and usually come down to the combination of chemicals combined with a catalysts or an oxidizer. These thrusters are simple (and can therefore be miniaturized easily), have low power requirements, and are very reliable.
Electric propulsion relies on electrical energy to accelerate charged particles to high speeds – aka. Hall-effect thrusters, ion thrusters, pulsed plasma thrusters, etc. This method is beneficial since it combines high specific-impulse with high-efficiency, and the components can be easily miniaturized. A disadvantage is that they require additional power, which means either larger solar cells, larger batteries, and more complex power systems.
Solar sails are also used as a method for propulsion, which is beneficial because it requires no propellant. Solar sails can also be scaled to the CubSat’s own dimensions, and the satellite’s small mass results in the greater acceleration for a given solar sail’s area.
However, solar sails still need to be quite large compared to the satellite, which makes mechanical complexity an added source of potential failure. At this time, few CubeSats have employed a solar sail, but it remains an area of potential development since it is the only method that needs no propellant or involves hazardous materials.
The Planetary Society’s LightSail-1 is one of the few concepts where a CubeSat relied on a solar sail. Credit: Josh Spradling/The Planetary Society.
Because the thrusters are miniaturized, they create several technical challenges and limitations. For instance, thrust vectoring (i.e. gimbals) is impossible with smaller thrusters. As such, vectoring must instead be achieved by using multiple nozzles to thrust asymmetrically or using actuated components to change the center of mass relative to the CubeSat’s geometry.
History:
Beginning in 1999, California Polytechnic State University and Stanford University developed the CubeSat specifications to help universities worldwide to perform space science and exploration. The term “CubeSat” was coined to denote nano-satellites that adhere to the standards described in the CubeSat design specifications.
These were laid out by aerospace engineering professor Jordi Puig-Suari and Bob Twiggs, from the Department of Aeronautics & Astronautics at Stanford University. It has since grown to become an international partnership of over 40 institutes that are developing nano-satellites containing scientific payloads.
Initially, despite their small size, academic institutions were limited in that they were forced to wait, sometimes years, for a launch opportunity. This was remedied to an extent by the development of the Poly-PicoSatellite Orbital Deployer (otherwise known as the P-POD), by California Polytechnic. P-PODs are mounted to a launch vehicle and carry CubeSats into orbit and deploy them once the proper signal is received from the launch vehicle.
The BisonSat is one example of a CubeSat mission launched by NASA’s CubeSat Launch Initiative on Oct. 8, 2015. Credits: Salish Kootenai College
The purpose of this, according to JordiPuig-Suari, was “to reduce the satellite development time to the time frame of a college student’s career and leverage launch opportunities with a large number of satellites.” In short, P-PODs ensure that many CubeSats can be launched at any given time.
Several companies have built CubeSats, including large-satellite-maker Boeing. However, the majority of development comes from academia, with a mixed record of successfully orbited CubeSats and failed missions. Since their inception, CubeSats have been used for countless applications.
For example, they have been used to deploy Automatic Identification Systems (AIS) to monitor marine vessels, deploy Earth remote sensors, to test the long term viability of space tethers, as well as conducting biological and radiological experiments.
Within the academic and scientific community, these results are shared and resources are made available by communicating directly with other developers and attending CubeSat workshops. In addition, the CubeSat program benefits private firms and governments by providing a low-cost way of flying payloads in space.
An artist’s rendering of MarCO A and B during the descent of InSight. NASA/JPL-Caltech
In 2010, NASA created the “CubeSat Launch Initiative“, which aims to provide launch services for educational institutions and non-profit organizations so they can get their CubeSats into space. In 2015, NASA initiated its Cube Quest Challenge as part of their Centennial Challenges Programs.
With a prize purse of $5 million, this incentive-competition aimed to foster the creation of small satellites capable of operating beyond low Earth orbit – specifically in lunar orbit or deep space. At the end of the competition, up to three teams will be selected to launch their CubeSat design aboard the SLS-EM1 mission in 2018.
NASA’s InSight lander mission (scheduled to launch in 2018), will also include two CubeSats. These will conduct a flyby of Mars and provide additional relay communications to Earth during the lander’s entry and landing.
Designated Mars Cube One (MarCO), this experimental 6U-sized CubeSat will will be the first deep-space mission to rely on CubeSat technology. It will use a high-gain, flat-paneled X-band antenna to transmit data to NASA’s Mars Reconnaissance Orbiter (MRO) – which will then relay it to Earth.
NASA engineers Joel Steinkraus and Farah Alibay demonstrate a full-scale mechanical mock-up of a MarCo CubeSat. Credit: NASA/JPL-Caltech
Making space systems smaller and more affordable is one of the hallmarks of the era of renewed space exploration. It’s also one of the main reasons the NewSpace industry has been growing by leaps and bounds in recent years. And with greater levels of participation, we are seeing greater returns when it comes to research, development and exploration.
