The sign of a truly great scientific theory is by the outcomes it predicts when you run experiments or perform observations. And one of the greatest theories ever proposed was the concept of Relativity, described by Albert Einstein in the beginning of the 20th century.
In addition to helping us understand that light is the ultimate speed limit of the Universe, Einstein described gravity itself as a warping of spacetime.
He did more than just provide a bunch of elaborate new explanations for the Universe, he proposed a series of tests that could be done to find out if his theories were correct.
One test, for example, completely explained why Mercury’s orbit didn’t match the predictions made by Newton. Other predictions could be tested with the scientific instruments of the day, like measuring time dilation with fast moving clocks.
Since gravity is actually a distortion of spacetime, Einstein predicted that massive objects moving through spacetime should generate ripples, like waves moving through the ocean.
The more massive the object, the more it distorts spacetime. Credit: LIGO/T. Pyle
Just by walking around, you leave a wake of gravitational waves that compress and expand space around you. However, these waves are incredibly tiny. Only the most energetic events in the entire Universe can produce waves we can detect.
It took over 100 years to finally be proven true, the direct detection of gravitational waves. In February, 2016, physicists with the Laser Interferometer Gravitational Wave Observatory, or LIGO announced the collision of two massive black holes more than a billion light-years away.
Any size of black hole can collide. Plain old stellar mass black holes or supermassive black holes. Same process, just on a completely different scale.
Colliding black holes. Credit: LIGO/A. Simonnet
Let’s start with the stellar mass black holes. These, of course, form when a star with many times the mass of our Sun dies in a supernova. Just like regular stars, these massive stars can be in binary systems.
Imagine a stellar nebula where a pair of binary stars form. But unlike the Sun, each of these are monsters with many times the mass of the Sun, putting out thousands of times as much energy. The two stars will orbit one another for just a few million years, and then one will detonate as a supernova. Now you’ll have a massive star orbiting a black hole. And then the second star explodes, and now you have two black holes orbiting around each other.
As the black holes zip around one another, they radiate gravitational waves which causes their orbit to decay. This is kind of mind-bending, actually. The black holes convert their momentum into gravitational waves.
As their angular momentum decreases, they spiral inward until they actually collide. What should be one of the most energetic explosions in the known Universe is completely dark and silent, because nothing can escape a black hole. No radiation, no light, no particles, no screams, nothing. And if you mash two black holes together, you just get a more massive black hole.
The gravitational waves ripple out from this momentous collision like waves through the ocean, and it’s detectable across more than a billion light-years.
Arial view of LIGO Livingston. Credit: The LIGO Scientific Collaboration
This is exactly what happened earlier this year with the announcement from LIGO. This sensitive instrument detected the gravitational waves generated when two black holes with 30 solar masses collided about 1.3 billion light-years away.
This wasn’t a one-time event either, they detected another collision with two other stellar mass black holes.
Regular stellar mass black holes aren’t the only ones that can collide. Supermassive black holes can collide too.
From what we can tell, there’s a supermassive black hole at the heart of pretty much every galaxy in the Universe. The one in the Milky Way is more than 4.1 million times the mass of the Sun, and the one at the heart of Andromeda is thought to be 110 to 230 million times the mass of the Sun.
In a few billion years, the Milky Way and Andromeda are going to collide, and begin the process of merging together. Unless the Milky Way’s black hole gets kicked off into deep space, the two black holes are going to end up orbiting one another.
Just with the stellar mass black holes, they’re going to radiate away angular momentum in the form of gravitational waves, and spiral closer and closer together. Some point, in the distant future, the two black holes will merge into an even more supermassive black hole.
View of Milkdromeda from Earth “shortly” after the merger, around 3.85-3.9 billion years from now. Credit: NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger
The Milky Way and Andromeda will merge into Milkdromeda, and over the future billions of years, will continue to gather up new galaxies, extract their black holes and mashing them into the collective.
Black holes can absolutely collide. Einstein predicted the gravitational waves this would generate, and now LIGO has observed them for the first time. As better tools are developed, we should learn more and more about these extreme events.
New Shepard Pusher Escape System. Credit: Blue Origin.
The last time an in-flight escape system test for a crew capsule took place was during the Apollo program, in 1966. Now, you can watch live as Blue Origin tests the escape system for their New Shepard rocket on Wednesday, October 5, 2016 at 10:45 a.m. ET. The test was originally planned for today (Tuesday) but was postponed because of inclement weather.
You can watch live here:
As founder Jeff Bezos described the test, “Our next flight is going to be dramatic, no matter how it ends.” If all goes well, the crew capsule (empty, this time) should land rather gently. The likely end for the rocket booster, however, will be its destruction in a ball of flames.
Dramatic, indeed.
The New Shepard rocket launching from its facility in West Texas. Image: Blue Origin
Although the New Shepard has already launched successfully four times since November 2015, this fifth flight will test the system to protect future passengers from any anomaly during launch. Unlike the Apollo escape system that used an escape “tower” motor located on top of the capsule to ‘pull’ the crew cabin away from a failing booster, New Shepard’s escape system is mounted underneath the capsule, to ‘push’ the capsule away from a potentially exploding booster.
As the video below from Blue Origin explains, “Like the airbag in your car, this full envelope capsule escape system is always there if needed.” Bezos also described the test in an email:
About 45 seconds after liftoff at about 16,000 feet, we’ll intentionally command escape. Redundant separation systems will sever the crew capsule from the booster at the same time we ignite the escape motor. The escape motor will vector thrust to steer the capsule to the side, out of the booster’s path. The high acceleration portion of the escape lasts less than two seconds, but by then the capsule will be hundreds of feet away and diverging quickly. It will traverse twice through transonic velocities – the most difficult control region – during the acceleration burn and subsequent deceleration. The capsule will then coast, stabilized by reaction control thrusters, until it starts descending. Its three drogue parachutes will deploy near the top of its flight path, followed shortly thereafter by main parachutes.
While SpaceX successfully tested their escape system in May 2015, it wasn’t an in-flight test. The Crew Dragon spacecraft abort system was launched off a specially built platform at Cape Canaveral Air Force Station’s Space Launch Complex 40 in Florida. The engines fired for about six seconds, instantly producing about 15,000 pounds of thrust each and lifting the spacecraft out over the Atlantic Ocean and parachuting safely into the water.
Bezos said that while they’d really like to retire this New Shepard booster and put it in a museum, that’s probably not a possibility.
New Shepard comes in for a landing with drag brakes and landing gear deployed. Image: Blue Origin.
“It’s the first ever rocket booster to fly above the Karman line into space and then land vertically upon the Earth,” he said. “But the booster was never designed to survive an in-flight escape. The capsule escape motor will slam the booster with 70,000 pounds of off-axis force delivered by searing hot exhaust. The aerodynamic shape of the vehicle quickly changes from leading with the capsule to leading with the ring fin, and this all happens at maximum dynamic pressure.”
Monte Carlo simulations show there’s some chance the booster can survive those stresses and land vertically as it’s done previously. But probably not. There will still be propellant on board and if it lands hard, as expected, Bezos said “its impact with the desert floor will be most impressive.”
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.
This illustration shows a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy, as it will unfold over the next several billion years. In this image, representing Earth's night sky in 3.75 billion years, Andromeda (left) fills the field of view and begins to distort the Milky Way with tidal pull. (Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger)
We don’t want to scare you, but our own Milky Way is on a collision course with Andromeda, the closest spiral galaxy to our own. At some point during the next few billion years, our galaxy and Andromeda – which also happen to be the two largest galaxies in the Local Group – are going to come together, and with catastrophic consequences.
Stars will be thrown out of the galaxy, others will be destroyed as they crash into the merging supermassive black holes. And the delicate spiral structure of both galaxies will be destroyed as they become a single, giant, elliptical galaxy. But as cataclysmic as this sounds, this sort of process is actually a natural part of galactic evolution.
Astronomers have know about this impending collision for some time. This is based on the direction and speed of our galaxy and Andromeda’s. But more importantly, when astronomers look out into the Universe, they see galaxy collisions happening on a regular basis.
The Antennae galaxies, a pair of interacting galaxies located 45 – 65 million light years from Earth. Credit: Hubble / ESA
Gravitational Collisions:
Galaxies are held together by mutual gravity and orbit around a common center. Interactions between galaxies is quite common, especially between giant and satellite galaxies. This is often the result of a galaxies drifting too close to one another, to the point where the gravity of the satellite galaxy will attract one of the giant galaxy’s primary spiral arms.
In other cases, the path of the satellite galaxy may cause it to intersect with the giant galaxy. Collisions may lead to mergers, assuming that neither galaxy has enough momentum to keep going after the collision has taken place. If one of the colliding galaxies is much larger than the other, it will remain largely intact and retain its shape, while the smaller galaxy will be stripped apart and become part of the larger galaxy.
Such collisions are relatively common, and Andromeda is believed to have collided with at least one other galaxy in the past. Several dwarf galaxies (such as the Sagittarius Dwarf Spheroidal Galaxy) are currently colliding with the Milky Way and merging with it.
However, the word collision is a bit of a misnomer, since the extremely tenuous distribution of matter in galaxies means that actual collisions between stars or planets is extremely unlikely.
Image obtained by the Hubble Space Telescope and the Keck-II telescope, showing a collision that took place billions of years ago. Credit: ESO/NASA/ESA/W. M. Keck Observatory
Andromeda–Milky Way Collision:
In 1929, Edwin Hubble revealed observational evidence which showed that distant galaxies were moving away from the Milky Way. This led him to create Hubble’s Law, which states that a galaxy’s distance and velocity can be determined by measuring its redshift – i.e. a phenomena where an object’s light is shifted toward the red end of the spectrum when it is moving away.
However, spectrographic measurements performed on the light coming from Andromeda showed that its light was shifted towards the blue end of the spectrum (aka. blueshift). This indicated that unlike most galaxies that have been observed since the early 20th century, Andromeda is moving towards us.
In 2012, researchers determined that a collision between the Milky Way and the Andromeda Galaxy was sure to happen, based on Hubble data that tracked the motions of Andromeda from 2002 to 2010. Based on measurements of its blueshift, it is estimated that Andromeda is approaching our galaxy at a rate of about 110 km/second (68 mi/s).
At this rate, it will likely collide with the Milky Way in around 4 billion years. These studies also suggest that M33, the Triangulum Galaxy – the third largest and brightest galaxy of the Local Group – will participate in this event as well. In all likelihood, it will end up in orbit around the Milky Way and Andromeda, then collide with the merger remnant at a later date.
Images from Hubble’s ACS in 2004 and 2005 show four examples of interacting galaxies (at various stages in the process) far away from Earth. Credit: NASA/ESA/J. Lotz, STScI/M. Davis, University of California, Berkeley/A. Koekemoer, STScI.
Consequences:
In a galaxy collision, large galaxies absorb smaller galaxies entirely, tearing them apart and incorporating their stars. But when the galaxies are similar in size – like the Milky Way and Andromeda – the close encounter destroys the spiral structure entirely. The two groups of stars eventually become a giant elliptical galaxy with no discernible spiral structure.
Such interactions can also trigger a small amount of star formation. When the galaxies collide, it causes vast clouds of hydrogen to collect and become compressed, which can trigger a series of gravitational collapses. A galaxy collision also causes a galaxy to age prematurely, since much of its gas is converted into stars.
After this period of rampant star formation, galaxies run out of fuel. The youngest hottest stars detonate as supernovae, and all that’s left are the older, cooler red stars with much longer lives. This is why giant elliptical galaxies, the results of galaxy collisions, have so many old red stars and very little active star formation.
Despite the Andromeda Galaxy containing about 1 trillion stars and the Milky Way containing about 300 billion, the chance of even two stars colliding is negligible because of the huge distances between them. However, both galaxies contain central supermassive black holes, which will converge near the center of the newly-formed galaxy.
Two galaxies colliding in the Corvus constellation. Credit: B. Whitmore (STScI), F. Schweizer (DTM),
This black hole merger will cause orbital energy to be transferred to stars, which will be moved to higher orbits over the course of millions of years. When the two black holes come within a light year of one another, they will emit gravitational waves that will radiate further orbital energy, until they merge completely.
Gas taken up by the combined black hole could create a luminous quasar or an active nucleus to form at the center of the galaxy. And last, the effects of a black hole merger could also kick stars out of the larger galaxy, resulting in hypervelocity rogue stars that could even carry their planets with them.
Today, it is understood that galactic collisions are a common feature in our Universe. Astronomy now frequently simulate them on computers, which realistically simulate the physics involved – including gravitational forces, gas dissipation phenomena, star formation, and feedback.
And be sure to check out this video of the impending galactic collision, courtesy of NASA:
Laika statue outside a research facility in Moscow (AP Photo/RIA-Novosti, Alexei Nikolsky)
Becoming an astronaut is a rare honor. The rigorous selection process, the hard training, and then… the privilege of going into space! It is something few human beings will ever be privileged enough to experience. But what about other species of animal that have gone into space? Are we not being just the slightest bit anthropocentric in singling out humans for praise?
What about all those brave simians and mice that were sent into space? What about the guinea pigs and rats? And what of “Man’s Best Friend”, the brave canines that helped pave the way for “manned” spaceflight? During the 1950s and 60s, the Soviets sent over 20 dogs into space, some of which never returned. Here’s what we know about these intrepid canines who helped make humanity a space-faring race!
Background:
During the 1950s and 60s, the Soviets and Americans found themselves locked in the Space Race. It was a time of intense competition as both superpowers attempted to outmaneuver the other and become the first to achieve spaceflight, conduct crewed missions to orbit, and eventually land crews on another celestial body (i.e. the Moon).
Albert II in preparation for his historic flight. Image Credit: NASA
Before crewed missions could be sent, however, both the Soviet space program and NASA conducted rigorous tests involving animal test subjects, as a way of gauging the stresses and physical tolls going into space would have. These tests were not without precedent, as animals had been used for aeronautical tests in previous centuries.
For instance, in 1783, the Montgolfier brothers sent a sheep, a duck and a rooster when testing their hot air balloon to see what the effects would be. Between 1947-1960, the US launched several captured German V-2 rockets (which contained animal test subjects) to measure the effect traveling to extremely high altitudes would have on living organisms.
Because of the shortage of rockets, they also employed high-altitude balloons. These tests were conducted using fruit flies, mice, hamsters, guinea pigs, cats, dogs, frogs, goldfish and monkeys. The most famous test case was Albert II, a rhesus monkey that became the first monkey to go into space on June 14th, 1949.
For the Soviets, it was felt that dogs would be the perfect test subjects, and for several reasons. For one, it was believed that dogs would be more comfortable with prolonged periods of inactivity. The Soviets also selected female dogs (due to their better temperament) and insisted on stray dogs (rather than house dogs) because they felt they would be able to tolerate the extreme stresses of space flight better.
Image of the type of safety module that was used to send Russian “space dogs” into orbit. Credit: WIkipedia Commons/Bricktop/Russia in Space
Training:
For the sake of preparing the dogs that were used for the sake of test flights, the Soviets confined the subjects in small boxes of decreasing size for periods of between 15 and 20 days at a time. This was designed to simulate spending time inside the small safety modules that would housed them for the duration of their flights.
Other exercises designed to get the dogs prepared for space flight included having them stand still for long periods of time. They also sought to get the dogs accustomed to wearing space suits, and made them ride in centrifuges that simulated the high acceleration experienced during launch.
Suborbital Flights:
Between 1951 and 1956, the Russians conducted their first test flights using dogs. Using R-1 rockets. a total of 15 missions were flown and were all suborbital in nature, reaching altitudes of around 100 km (60 mi) above sea level. The dogs that flew in these missions wore pressure suits with acrylic glass bubble helmets.
Model of R-1 rocket at Znamensk City, near Kapustin Yar missile range. Credit: Wikipdia Commons/function.mil.ru
The first to go up were Dezik and Tsygan, who both launched aboard an R-1 rocket on July 22nd, 1951. The mission flew to a maximum altitude of 110 km, and both dogs were recovered unharmed afterwards. Dezik made another sub-orbital flight on July 29th, 1951, with a dog named Lisa, although neither survived because their capsule’s parachute failed to deploy on re-entry.
Several more launches took place throughout the Summer and Fall of 1951, which included the successful launch and recovery of space dogs Malyshka and ZIB. In both cases, these dogs were substitutes for the original space dogs – Smelaya and Bolik – who ran away just before the were scheduled to launch.
By 1954, space dogs Lisa-2 (“Fox” or “Vixen”, the second dog to bear this name after the first died), Ryzhik (“Ginger” because of the color of her fur) made their debut. Their mission flew to an altitude of 100 km on June 2nd, 1954, and both dogs were recovered safely. The following year, Albina and Tsyganka (“Gypsy girl”) were both ejected out of their capsule at an altitude of 85 km and landed safely.
Between 1957 to 1960, 11 flights with dogs were made using the R-2A series of rockets, which flew to altitudes of about 200 km (124 mi). Three flights were made to an altitude of about 450 km (280 mi) using R-5A rockets in 1958. In the R-2 and R-5 rockets, the dogs were contained in a pressured cabin
Photo of Otvazhnaya and the Mafrusha, two of the three brave cosmonauts who flew together on July 2nd, 1959. Credit: Wikipedia Commons (.ru)
Those to take part in these launches included Otvazhnaya (“Brave One”) who made a flight on July 2nd, 1959, along with a rabbit named Marfusha (“Little Martha”) and another dog named Snezhinka (“Snowflake”). Otvazhnaya would go to make 5 other flights between 1959 and 1960.
Orbital Flights:
By the late 1950s, and as part of the Sputnik and Vostok programs, Russian dogs began to be sent into orbit around Earth aboard R-7 rockets. On November 3rd, 1957, the famous space dog Laika became the first animal to go into orbit as part of the Sputnik-2 mission. The mission ended tragically, with Laika dying in flight. But unlike other missions where dogs were sent into suborbit, her death was anticipated in advance.
It was believed Laika would survive for a full ten days, when in fact, she died between five and seven hours into the flight. At the time, the Soviet Union claimed she died painlessly while in orbit due to her oxygen supply running out. More recent evidence however, suggests that she died as a result of overheating and panic.
This was due to a series of technical problems which resulted from a botched deployment. The first was the damage that was done to the thermal system during separation, the second was some of the satellite’s thermal insulation being torn loose. As a result of these two mishaps, temperatures in the cabin reached over 40º C.
The famous space dog Laika, pictured here before her launch in 1957. Credit: AP Photo/NASA
The mission lasted 162 days before the orbit finally decayed and it fell back to Earth. Her sacrifice has been honored by many countries through a series of commemorative stamps, and she was honored as a “hero of the Soviet Union”. Much was learned from her mission about the behavior of organisms during space flight, though it has been argued that what was learned did not justify the sacrifice.
The next dogs to go into space were Belka (“Squirrel”) and Strelka (“Little Arrow”), which took place on Aug. 19th, 1960, as part of the Sputnik-5 mission. The two dogs were accompanied by a grey rabbit, 42 mice, 2 rats, flies, and several plants and fungi, and all spent a day in orbit before returning safely to Earth.
Strelka went on to have six puppies, one of which was named Pushinka (“Fluffy”). This pup was presented to President John F. Kennedy’s daughter (Caroline) by Nikita Khrushchev in 1961 as a gift. Pushinka went on to have puppies with the Kennedy’s dog (named Charlie), the descendants of which are still alive today.
On Dec. 1st, 1960, space dogs Pchyolka (“Little Bee”) and Mushka (“Little Fly”) went into space as part of Sputnik-6. The dogs, along with another compliment of various test animals, plants and insects, spent a day in orbit. Unfortunately, all died when the craft’s retrorockets experienced an error during reentry, and the craft had to be intentionally destroyed.
The dogs Veterok and Ugoljok, who spent 22 days in orbit as part of the Cosmos 110 mission. Credit: Wikipedia Commons/Tekniska museet
Sputnik 9, which launched on March 9th, 1961, was crewed by spacedog Chernenko (“Blackie”) – as well as a cosmonaut dummy, mice and a guinea pig. The capsule made one orbit before returning to Earth and making a soft landing using a parachute. Chernenko was safely recovered from the capsule.
On March 25th, 1961, the dog Zvyozdocha (“Starlet”) who was named by Yuri Gagarin, made one orbit on board the Sputnik-10 mission with a cosmonaut dummy. This practice flight took place a day before Gagarin’s historic flight on April 12th, 1961, in which he became the first man to go into space. After re-entry, Zvezdochka safely landed and was recovered.
Spacedogs Veterok (“Light Breeze”) and Ugolyok (“Coal”) were launched on board a Voskhod space capsule on Feb. 22nd, 1966, as part of Cosmos 110. This mission, which spent 22 days in orbit before safely landing on March 16th, set the record for longest-duration spaceflight by dogs, and would not be broken by humans until 1971.
Legacy:
To this day, the dogs that took part in the Soviet space and cosmonaut training program as seen as heroes in Russia. Many of them, Laika in particular, were put on commemorative stamps that enjoyed circulation in Russia and in many Eastern Bloc countries. There are also monuments to the space dogs in Russia.
Romanian commemorate stamp showing Laika, the first dog launched into space, from Rumania Posta, 1957. Credit: Wikipedia Commons
These include the statue that exists outside of Star City, the Cosmonaut training facility in Moscow. Created in 1997, the monument shows Laika positioned behind a statue of a cosmonaut with her ears erect. The Monument to the Conquerors of Space, which was constructed in Moscow in 1964, includes a bas-relief of Laika along with representations of all those who contributed to the Soviet space program.
On April 11, 2008, at the military research facility in Moscow where Laika was prepped for her mission to space, officials unveiled a monument of her poised inside the fuselage of a space rocket (shown at top). Because of her sacrifice, all future missions involving dogs and other test animals were designed to be recoverable.
Four other dogs died in Soviet space missions, including Bars and Lisichka (who were killed when their R-7 rocket exploded shortly after launch). On July 28, 1960, Pchyolka and Mushka also died when their space capsule was purposely destroyed after a failed re-entry to prevent foreign powers from inspecting the capsule.
However, their sacrifice helped to advance safety procedures and abort procedures that would be used for many decades to come in human spaceflight.
We’ve had an abundance of news stories for the past few months, and not enough time to get to them all. So we are now using a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!
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We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Universe Today, or the Universe Today YouTube page.
So if you’ve been to Yellowstone National Park, you’ve seen one of the most amazing features of the natural world – geysers. In today’s episode, we’re going to talk about geysers on Earth, and where they might be in the solar system.
We usually record Astronomy Cast as a live Google+ Hangout on Air every Friday at 1:30 pm Pacific / 4:30 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.
Rosetta’s OSIRIS narrow-angle camera captured this image of Comet 67P/Churyumov-Gerasimenko from an altitude of about 16 km above the surface during the spacecraft’s final descent on September 30, 2016. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
With a soft “awwww” from the mission team in the control center in Darmstadt, Germany, the signal from the Rosetta spacecraft faded, indicating the end of its journey. Rosetta made a controlled impact onto Comet 67P/Churyumov–Gerasimenko, sending back incredible close-up images during descent, after two years of investigations at the comet.
“Farewell Rosetta. You have done the job. That was space science at its best,” said Patrick Martin, Rosetta mission manager.
Rosetta’s final resting spot appears to be in a region of active pits in the Ma’at region on the two-lobed, duck-shaped comet.
The information collected during the descent – as well as during the entire mission – will be studied for years. So even though the video below about the mission’s end will likely bring a tear to your eye, rest assured the mission will continue as the science from Rosetta is just getting started.
“Rosetta has entered the history books once again,” says Johann-Dietrich Wörner, ESA’s Director General. “Today we celebrate the success of a game-changing mission, one that has surpassed all our dreams and expectations, and one that continues ESA’s legacy of ‘firsts’ at comets.”
Launched in 2004, Rosetta traveled nearly 8 billion kilometers and its journey included three Earth flybys and one at Mars, and two asteroid encounters. It arrived at the comet in August 2014 after being in hibernation for 31 months.
After becoming the first spacecraft to orbit a comet, it deployed the Philae lander in November 2014. Philae sent back data for a few days before succumbing to a power loss after it unfortunately landed in a crevice and its solar panels couldn’t receive sunlight. But Rosetta continued to monitor the comet’s evolution as it made its closest approach and then moved away from the Sun. However, now Rosetta and the comet are too far away from the Sun for the spacecraft to receive enough power to continue operations.
“We’ve operated in the harsh environment of the comet for 786 days, made a number of dramatic flybys close to its surface, survived several unexpected outbursts from the comet, and recovered from two spacecraft ‘safe modes’,” said operations manager Sylvain Lodiot. “The operations in this final phase have challenged us more than ever before, but it’s a fitting end to Rosetta’s incredible adventure to follow its lander down to the comet.”
Compilation of the brightest outbursts seen at Comet 67P/Churyumov–Gerasimenko by Rosetta’s OSIRIS narrow-angle camera and Navigation Camera between July and September 2015. Credit: OSIRIS: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA; NavCam: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0.
Rosetta’s Legacy and Discoveries
Of its many discoveries, Rosetta’s close-up views of the curiously-shaped Comet 67P have already changed some long-held ideas about comets. With the discovery of water with a different ‘flavor’ to that of Earth’s oceans, it appears that Earth impacts of comets like 67P/Churyumov–Gerasimenko may not have delivered as much of Earth’s water as previously thought.
From Philae, it was determined that even though organic molecules exist on the comet, they might not be the kind that can deliver the chemical prerequisites for life. However, a later study revealed that complex organic molecules exist in the dust surrounding the comet, such as the amino acid glycine, which is commonly found in proteins, and phosphorus, a key component of DNA and cell membranes. This reinforces the idea that the basic building blocks may have been delivered to Earth from an early bombardment of comets.
Rosetta’s long-term monitoring has also shown just how important the comet’s shape is in influencing its seasons, in moving dust across its surface, and in explaining the variations measured in the density and composition of the comet’s coma.
And because of Rosetta’s proximity to the comet, we all went along for the ride as the spacecraft captured views of what happens as a comet comes close to the Sun, with ice sublimating and dusty jets exploding from the surface.
Studies of the comet show it formed in a very cold region of the protoplanetary nebula when the Solar System was forming more than 4.5 billion years ago. The comet’s two lobes likely formed independently, but came together later in a low-speed collision.
“Just as the Rosetta Stone after which this mission was named was pivotal in understanding ancient language and history, the vast treasure trove of Rosetta spacecraft data is changing our view on how comets and the Solar System formed,” said project scientist Matt Taylor.
Sequence of images captured by Rosetta during its descent to the surface of Comet 67P/C-G on September 30, 2016. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
Journey’s End
During the final hours of the mission on Friday morning, the instrument teams watched the data stream in and followed the spacecraft as it moved closer to its targeted touchdown location on the “head” of the 4km-wide comet. The pitted region where Rosetta landed appear to be the places where 67P ejects gas and dust into space, and so Rosetta’s swan song will provide more insight into the comet’s icy jets.
“With the decision to take Rosetta down to the comet’s surface, we boosted the scientific return of the mission through this last, once-in-a-lifetime operation,” said Martin. ““It’s a bittersweet ending, but … Rosetta’s destiny was set a long time ago. But its superb achievements will now remain for posterity and be used by the next generation of young scientists and engineers around the world.”
And so, my final day dawns.
Just a few grains are left to drain through
The hourglass of my life.
The Comet is a hole in the sky.
Rolling, turning, a black void churning
Silently beneath me.
Down there, waiting for me, Philae sleeps,
Its bed a cold cave floor,
A quilt of sparkling hoarfrost
Pulled over its head…
I have so little time left;
I sense Death flying behind me,
I feel his breath on my back as I look down
At Ma’at, its pits as black as tar,
A skulls’s empty eye sockets staring back
At me, daring me to leave the safety
Of this dusty sky and fly down to join them,
Never to spread my wings again; never
To soar over The Comet’s tortured pinnacles and peaks,
Or play hide and seek in its jets and plumes…
I don’t want to go.
I don’t want to be buried beneath that filthy snow.
This is wrong! I want to fly on!
There is so much more for me to see,
So much more to do –
But the end is coming soon.
All I ask of you is this: don’t let me crash.
Help me land softly, kissing the ground,
Coming to rest with barely a sound
Like a leaf falling from a tree.
Don’t let me die cartwheeling across the plain,
Wings snapping, cameras shattering,
Pieces of me scattering like shrapnel
Across the ice. Let me end my mayfly life
In peace, whole, not as debris rolling uncontrollably
Into Deir el-Medina…
It’s time to go, I know.
Only hours remain until I join Philae
And my great adventure ends
So I’ll send this and say goodbye.
If I dream, I’ll dream of Earth
Turning beneath me, bathing me in
Fifty shades of blue…
In years to come I hope you’ll think of me
And smile, remembering how, for just a while,
We explored a wonderland of ice and dust
Together, hand in hand.
