When it comes to space, the first thing most people think of is NASA. Or Russia and the European Space Agency, or even more recently, countries like China and Japan. In the public eye, Canada has tended to be a bit farther down on the list. There is the Canadian Space Agency, but it is better known for developing space and satellite technologies, not awe-inspiring launches to the Moon or other planets, which naturally tend to get the most attention.
Canada has its own astronauts, too, but they go into orbit on the Space Shuttle or Russian rockets. Canada’s role in space should not, however, be underestimated. It was, for example, the first country to have a domestic communications satellite in geostationary orbit, Anik A1, in 1972. There is also the well-known Canadarm used on the Space Shuttle and Canadarm2 on the International Space Station, as well as the space robot Dextre on the ISS. Canada has also contributed technology to various robotic planetary missions as well.
But even in these times of budget constraints, new ventures are being planned, including a mission to place two video cameras on the International Space Station late next year, via a Russian mission.
The cameras will provide near real-time video broadcasting continuously in high-definition. The cameras are being developed by Urthecast, a Vancouver-based firm, which is investing $10 million in the project.
Like their American counterparts now, the investment and development of space technology is coming increasingly from the private sector instead of the government. In 1996, the Canadian government contributed 32% to domestic space revenue; in 2010, it was only 18% and it is estimated to drop again over the next three years.
Because of smaller budgets, the CSA focuses on assisting with larger missions from other countries instead of developing its own launch vehicles. According to Mark Burbidge, head of industrial policy at the CSA, the Canadian Space Agency doesn’t have the money for such projects. “That got our astronauts up there,” he says, referring to the Canadarm.
Another area that Canada may be able to contribute to is space tourism, a prime example of private companies becoming involved in the space business. Companies like SpaceX, Virgin Galactic and Bigelow Airspace are changing the way that people will go into near-orbit and low-Earth orbit. No dependence solely on government dollars to finance their objectives such as tourist space flights, small orbiting hotels or launching commercial satellites.
At this stage, government funding is still often required, especially for smaller firms, but the future looks promising. Space companies are becoming gradually less reliant on the government for revenue growth. The investment return tends to be primarily a scientific one, according to Dr. Jean de Lafontaine, founder of space services company NGC Aerospace in Quebec, making space tourism more of an ideal option for private companies.
This would seem to be an optimum arrangement, allowing companies to compete in orbital missions and tourism, while government agencies like NASA, ESA, etc. are better able to invest in larger-scale planetary missions and other costly space projects (noting however that some commercial companies also have their eyes on the Moon and Mars).
Canada may not have its own rockets or grandiose space missions, not yet anyway, but it will continue to make important contributions to space exploration. And as a Canadian, I am very pleased about that!
Three satellites fly in formation as part of the Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) investigation. Image Credit: NASA
[/caption]In an interesting case of science fiction becoming a reality, NASA has been testing their SPHERES project over the past few years. The SPHERES project (Synchronized Position Hold, Engage, Reorient, Experimental Satellites) involves spherical satellites about the size of a bowling ball. Used inside the International Space Station, the satellites are used to test autonomous rendezvous and docking maneuvers. Each individual satellite features its own power, propulsion, computers and navigational support systems.
The SPHERES project is the brainchild of David Miller (Massachusetts Institute of Technology). Miller was inspired by the floating remote “droid” that Luke Skywalker used to help hone his lightsaber skills in Star Wars. Since 2006, a set of five SPHERES satellites, built by Miller and his students have been onboard the International Space Station.
Since lightsabers are most likely prohibited onboard the ISS, what practical use have these “droids” been to space station crews?
The first SPHERES satellite was tested during Expedition 8 and Expedition 13, with a second unit delivered to the ISS by STS-121, and a third delivered by STS-116. The crew of ISS Expedition 14 tested a configuration using three of the SPHERES satellites. Since their arrival, over 25 experiments have been performed using SPHERES. Until recently, the tests used pre-programmed algorithms to perform specific functions.
“The space station is just the first step to using remotely controlled robots to support human exploration,” said Chris Moore, program executive in the Exploration Systems Mission Directorate at NASA Headquarters in Washington. “Building on our experience in controlling robots on station, one day we’ll be able to apply what we’ve learned and have humans and robots working together everywhere from Earth orbit, to the Moon, asteroids, and Mars.”
International Space Station researcher Mike Fossum, commander of Expedition 29, puts one of the Smart SPHERES through its paces. Image Credit: NASAIn November, the SPHERES satellites were upgraded with “off-the-shelf” smartphones by using an “expansion port” Miller’s team designed into each satellite.
“Because the SPHERES were originally designed for a different purpose, they need some upgrades to become remotely operated robots,” said DW Wheeler, lead engineer in the Intelligent Robotics Group at Ames.
Wheeler added, “By connecting a smartphone, we can immediately make SPHERES more intelligent. With the smartphone, the SPHERES will have a built-in camera to take pictures and video, sensors to help conduct inspections, a powerful computing unit to make calculations, and a Wi-Fi connection that we will use to transfer data in real-time to the space station and mission control.”
In order to make the smartphones safer to use onboard the station, the cellular communications chips were removed, and the lithium-ion battery was replaced with AA alkaline batteries.
By testing the SPHERES satellites, NASA can demonstrate how the smart SPHERES can operate as remotely operated assistants for astronauts in space. NASA plans additional tests in which the compact assistants will perform interior station surveys and inspections, along with capturing images and video using the smartphone camera. Additional goals for the mission include the simulation of free-flight excursions, and possibly other, more challenging tasks.
“The tests that we are conducting with Smart SPHERES will help NASA make better use of robots as assistants to and versatile support for human explorers — in Earth orbit or on long missions to other worlds and new destinations,” said Terry Fong, project manager of the Human Exploration Telerobotics project and Director of the Intelligent Robotics Group at NASA’s Ames Research Center in Moffett Field, Calif.
Artist's conception of a terraformed Mars. Credit: Ittiz/Wikimedia Commons
As we continue to explore farther out into our solar system and beyond, the question of habitation or colonization inevitably comes up. Manned bases on the Moon or Mars for example, have long been a dream of many. There is a natural desire to explore as far as we can go, and also to extend humanity’s presence on a permanent or at least semi-permanent basis. In order to do this, however, it is necessary to adapt to different extreme environments. On the Moon for example, a colony must be self-sustaining and protect its inhabitants from the airless, harsh environment outside.
Mars, though, is different. While future bases could adapt to the Martian environment as well, there is also the possibility of modifying the surrounding environment instead of just co-existing with it. This is the process of terraforming – essentially trying to tinker with Mars’ atmosphere and environment to make it more Earth-like. Although still a long ways off technologically, terraforming the Red Planet is seen as a future possibility. Perhaps the bigger question is, should we?
One of the main issues is whether Mars has any indigenous life or not – how does this affect the question of colonization or terraforming?
If Mars does have any kind of biosphere, it should be preserved as much as possible. We still don’t know yet if any such biosphere exists, but the possibility, which has only increased based on recent discoveries, must be taken into account. Such a precious discovery, which could teach us immensely about how life arose on both worlds, should be completely off-limits. Small colonies might be fine, but living on Mars should not be at the expense of any native habitats, if they exist. The most likely place to find life on Mars is underground. If the surface is truly as sterile and barren as it seems to be, then colonies there shouldn’t be too much of a problem. It has also been suggested that Martian caves would make ideal human habitats, serving as natural protection from the harsh conditions on the surface. True, but if it turned out that something else was already taking up residence in them, then we should leave them alone. If Mars is home to any indigenous life, then terraforming should be a non-issue.
What if Mars is lifeless? Even if no life otherwise exists there, that pristine and unique alien environment, so far barely scratched by humans, needs to be preserved as is as much as possible. We’ve already done too much damage here on our own planet. By studying Mars and other planets and moons in their current natural state, we can learn so much about their history and also learn more about our own world in that context. We should appreciate the differences in and variety of worlds instead of just transforming them to suit our own ambitions.
There is also the more current but related problem of contamination. There has been a long-standing protocol, via the 1967 Outer Space Treaty, to have all spacecraft going to the Moon or Mars sterilized as much as possible. If bacteria from Earth made it to the Martian surface and survived, it would complicate the search for life there; if a lander or rover was to later identify living organisms in the soil, it might be difficult to determine whether they were just contamination or true native life forms. From both a scientific and ethical perspective, it would seem prudent to try to protect Mars as much as we can from earthly intruders. This applies equally to whether Mars is already inhabited or not. Fortunately, for almost any kind of bacteria or other microrganisms from Earth, it would be very difficult if not impossible to survive on the Martian surface, nevermind flourish. The risk of planet-wide contamination is very negligible, but it is still better to take strict preventive measures than to play with chance.
See also this excellent paper by astrobiologist Chris McKay. Some different views from this article on whether Mars should be protected and preserved at all costs or altered to help life to flourish there, but is a good presentation of the current ideas being put on the table. From the summary:
“Planetary ecosynthesis on Mars is being seriously discussed within the field of planetary science. It appears that restoring a thick atmosphere on Mars and the recreation of an environment habitable to many forms of life is possible. It is important now toconsider if it “should” be done. To do this takes us into new and interesting territory in environmental ethics but both utilitarian and intrinsic worth arguments support the notion of planetary ecosynthesis. Strict preservationism arguments do not. It is important to have the long-term view of life on Mars and the possibilities of planetary ecosynthesis. This affects how we explore Mars now. Mars may well be our first step out into the biological universe, it is a step we should take carefully.”
The James Webb Space Telescope mirrors have completed deep-freeze tests and are removed from the X-ray and Cryogenic test Facility at Marshall Space Flight Center. Credit: Emmett Given, NASA Marshall
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The last of the 21 mirrors for the James Webb Space Telescope have come out of deep freeze – literally! – and are now approved for space operations, a major milestone in the development of the next generation telescope that’s being hailed as the “successor to Hubble.”
“The mirror completion means we can build a large, deployable telescope for space,” said Scott Willoughby, vice president and Webb program manager at Northrop Grumman Aerospace Systems. “We have proven real hardware will perform to the requirements of the mission.”
The all-important mirrors for the Webb telescope had to be cryogenically tested to make sure they could withstand the rigors and extreme low temperatures necessary for operating in space. To achieve this, they were cooled to temperatures of -387F (-233C) at the X-ray and Cryogenic Test Facility at Marshall Space Flight Center.
When in actual use, the mirrors will be kept at such low temperatures so as not to interfere with deep-space infrared observations with their own heat signatures.
JWST engineers anticipate that, with such drastic cooling, the mirrors will change shape. The testing proved that the mirrors would achieve the shapes needed to still perform exactly as expected.
“This testing ensures the mirrors will focus crisply in space, which will allow us to see new wonders in our universe,” said Helen Cole, project manager for Webb Telescope mirror activities.
Planned for launch in 2018, the JWST will be the premier observatory of the next decade, serving thousands of astronomers worldwide. It will study every phase in the history of the Universe, ranging from the first luminous glows after the Big Bang to the formation of solar systems capable of supporting life on Earthlike planets.
Learn more about the James Webb Space Telescope here.
Artist concept of the Membrane Optical Imager for Real-Time Exploitation (MOIRE). Credit: DARPA
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“It sees you when you’re sleeping and knows when you’re awake” could be the theme song for a new spy satellite being developed by DARPA. The Defense Advanced Research Projects Agency’s latest proof-of-concept project is called the Membrane Optical Imager for Real-Time Exploitation (MOIRE), and would provide real-time images and video of any place on Earth at any time — a capability that, so far, only exists in the realm of movies and science fiction. The details of this huge eye-in-the-sky look like something right out of science fiction, as well, and it would be interesting to determine if it could have applications for astronomy as well.
MOIRE would be a geosynchronous orbital system that uses a huge but lightweight membrane optic. A 20-meter-wide membrane “eye” would be etched with a diffractive pattern, according to DARPA, which would focus light on a sensor. Reportedly it will cost $500 million USD for each space-based telescope, and it would be able to image an area greater than 100 x 100 km with a video update rate of at least one frame a second.
DARPA says the program aims to demonstrate the ability to manufacture large membranes and large structures to hold the optics flat, and also demonstrate the secondary optical elements needed to turn a diffraction-based optic into a wide bandwidth imaging device.
The MOIRE program began in March 2010 is now in the first phase of development, where DARPA is testing the concept’s viability. Phase 2 would entail system design, with Ball Aerospace doing the design and building to test a 16-foot (5 m) telescope, and an option for a Phase 3 which would include a demonstration of the system, launching a 32-foot (10 m) telescope for flight tests in orbit.
The 20 meter (66 ft) design is quite a bit larger than NASA’s next-generation James Webb Space Telescope that has an aperture of 21 feet (6.5 m).
Public Intelligence reports that such a telescope should be able to spot missile launcher vehicles moving at speeds of up to 60 mph on the ground, according to a DARPA contract. That would also require the image resolution to see objects less than 10 feet (3 m) long within a single image pixel.
Can we order one for looking for extrasolar planets?
The Voyager 1 spacecraft has started to transverse what JPL has dubbed as a "cosmic purgatory" between our solar system - and interstellar space. Image Credit: NASA/JPL
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Voyager 1 is in uncharted territory. The long-lived spacecraft has entered a new region of space that lies between where our solar system ends and where interstellar space begins. This area is not a place of sightseeing however, as a NASA press release referred to it as a kind of “cosmic purgatory.”
Here, the solar winds ebb somewhat, the magnetic field increases and charged particles from within our solar system – is leaking out into interstellar space. This data has been compiled from information received from Voyager 1 over the course of the last year.
The Voyager spacecraft's compliment of scientific instruments have provided scientists back on Earth with information about what the space environment at the fringes of our sun's influence is truly like. Image Credit: NASA/JPL - Caltech
“Voyager tells us now that we’re in a stagnation region in the outermost layer of the bubble around our solar system,” said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena. “Voyager is showing that what is outside is pushing back. We shouldn’t have long to wait to find out what the space between stars is really like.”
Despite the fact that Voyager 1 is approximately 11 billion miles (18 billion kilometers) distant from the sun – it still has not encounter interstellar space. The information that scientists have gleaned from the Voyager 1 spacecraft indicates that the spacecraft is still located within the heliosphere. The heliosphere is a “bubble” of charged particles that the sun blows around itself and its retinue of planets.
Voyager 1 has traveled far past the realm of the gas or even ice giants and is now in uncharted territory where scientists are learning more and more about the dynamic environment at the far-flung edges of our solar system. Image Credit: NASA/JPL - Caltech
The latest findings were made using Voyager’s Low Energy Charged Particle instrument, Cosmic Ray Subsystem and Magnetometer.
Experts are not certain how long it will take the Voyager 1 spacecraft to finally breach this bubble and head out into interstellar space. Best estimates place the length of time when this could happen anywhere from the next few months – to years. These findings counter findings announced in April of 2010 that showed that Voyager 1 had essentially crossed the heliosphere boundary. The discoveries made during the past year hint that this region of space is far more dynamic than previously thought.
Voyager 1 has entered into a region of space between the sun's influence and the beginning of interstellar space that NASA has dubbed the "stagnation region." Image Credit: NASA/JPL - Caltech
The magnetometer aboard Voyager 1 has picked up an increase in the intensity of the magnetic field located within this “stagnation field.” Essentially the inward pressure from interstellar space is compressing the magnetic field to twice its original density. The spacecraft has also detected a 100-fold increase in the intensity of high-energy electrons diffusing into our solar system from outside – this is yet another indicator that Voyager 1 is approaching the heliosphere.
The interplanetary probe was launched from Cape Canaveral Air Force Station’s Space Launch Complex 41 (SLC-41) on Sept. 5, 1977, Voyager 1’s sister ship, Voyager 2 is also in good health and is about 9 billion miles (15 billion kilometers) from the sun (it too was launched in 1977). The spacecraft itself was built by NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
“Voyager is a mission of discovery and it’s at the edge of the solar system still making discoveries,” said Stone said. “The stagnation is the latest in the whole journey of discovery. We are all excited because we believe it means we’re getting very close to boundary of heliosphere and the entry into interstellar space.”
Both of the Voyager spacecraft were thrust to orbit by the powerful Titan boosters - and both in the same year - 1977. Photo Credit: NASA
The Orbital Test Vehicle or OTV has been launched twice by the United States Air Force. There is one currently on orbit that has had its mission extended - past the officially stated endurance time that the USAF had previously announced. Photo Credit: USAF
Video provided courtesy of United Launch Alliance
The United States Air Force’s second flight of the X-37B – is headed into extra innings. Known as the Orbital Test Vehicle 2 (OTV-2) this robotic mini space shuttle launched from Cape Canaveral Air Force Station’s Space Launch Complex 41 (SLC-41) on Mar. 5, 2011. Although the U.S. Air Force has kept mum regarding details about the space plane’s mission – it has announced that the OTV-2 has exceeded its endurance limit of 270 days on orbit as of the end of November.
The OTV is launched atop a United Launch Alliance (ULA) Atlas V 501 rocket. The space plane is protected within a fairing until it reaches orbit. After separation, the diminutive shuttle begins its mission.
OTV mission USA-226, as it is officially known, is by all accounts going smoothly and the spacecraft is reported to be in good health. The U.S. Air Force has not announced when OTV-2 will be directed to land.
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The fact that the space plane will continue to orbit beyond what its stated limits are highlights that the OTV has greater capabilities than what was officially announced. The first OTV flight launched in April of 2011 and landed 224 days later at Vandenberg Air Force Base in California. The U.S. Air Force is undoubtedly being more judicious with fuel stores on board the robotic spacecraft, allowing for a longer duration flight.
Much like NASA’s retired fleet of space shuttle orbiters, the OTV has a payload bay that allows for payloads and experiments to be conducted on-orbit. What payloads the U.S. Air Force has had on either mission – remains a secret.
Boeing has announced that the X-37B could be modified to conduct crewed missions to and from orbit. Tentatively named the X-37C, this spacecraft would be roughly twice the size of its unmanned cousin. If this variant goes into service it would be used to transport astronauts to and from the orbiting International Space Station (ISS).
OTV USA-226 launched on Mar. 5, 2011 and has helped prove out the mini space plane's design. Photo Credit: Alan Walters/awaltersphoto.com
The X-37B has become a bit controversial of late. Members of the Chinese press have stated that the space plane raises concerns of an arms race in space. Xinhua News Agency and China Daily have expressed concern that the OTVs could be used to deliver weapons to orbit. The Pentagon has flatly denied these allegations. The clandestine nature of these flights have led to a wide variety of theories as to what the OTVs have been used to ferry to orbit.
If all goes according to how it is planned, Curiosity will touch down safely on the surface of Mars in August of 2012. Photo Credit: Alan walters/awaltersphoto.com
Launch video provided courtesy of United Launch Alliance
CAPE CANAVERAL, Fla – It is a mission years in the making. However, it would not be possible without the hard work of an army’s worth of engineers – and the systems that they built. How many different systems and engines are required to get the Mars Science Laboratory (MSL) rover named Curiosity to the surface of the Red Planet? The answer might surprise you.
Including the two engines that are part of the Atlas V 541 launch vehicle, it will take 50 different engines and thrusters in total to work perfectly to successfully deliver Curiosity to the dusty plains of Mars.
Starting with the launch vehicle itself, there are six separate engines that power the six-wheeled rover, safely ensconced in its fairing, out of Earth’s gravity well. For the first leg of the journey four powerful Solid Rocket Boosters (SRBs) provided by Aerojet (each of these provides 400,000 lbs of thrust) will launch the rover out of Earth’s atmosphere.
The United Launch Alliance (ULA) Atlas launch vehicle has two rocket engines that provide the remaining amount of thrust required to get MSL to orbit and send the rover on its way to Mars. The first is the Russian-built RD-180 engine (whose thrust is split between two engine bells) the second is the Centaur second stage. There are four Aerojet solid rocket motors that help the booster and Centaur upper stage to separate.
The Centaur’s trajectory is controlled by both thrust vector control of the main engine as well as a Reaction Control System or RCS comprised of liquid hydrazine propulsion systems (there are twelve roll control thrusters on the Centaur upper stage).
MSL’s cruise stage separates entirely from the Centaur upper stage and is on the long road to the Red Planet. The cruise stage has eight one-pound-thrust hydrazine thrusters that are used for trajectory maneuvers for the nine-month journey to Mars. These are used for minor corrections to keep the spacecraft on the correct course.
Curiosity’s first physical encounter with the Martian environment is referred to as Entry, Descent and Landing (EDL) – more commonly known as “six minutes of terror” – the point when mission control, back on Earth, loses contact with the spacecraft as it enters the Martian atmosphere.
Video courtesy of Lockheed Martin
Even though Mars only has roughly one percent of Earth’s atmosphere, the friction of the atmosphere caused by a spacecraft impacting it at 13,200 miles per hour (about 5,900 meters per second) – is enough to melt Curiosity if it were exposed to these extremes. The heat shield, located at the base of the cruise stage, prevents this from happening.
The heat shield, provided by Lockheed-Martin, on MSL’s cruise stage is 14.8 feet (4.5 meters) in diameter. By comparison, the heat shields that were used on the Apollo manned missions to the Moon were 13 feet (4 meters) in diameter and the ones that allowed the Mars Exploration Rovers Spirit and Opportunity to safely reach the surface of Mars were 8.7 feet (2.65 meters) in diameter.
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At this point in the mission eight engines, each providing 68 pounds of thrust come into play. These engines provide all of the trajectory control during EDL – meaning they will fire almost continuously.
Shortly thereafter – BOOM – the parachute deploy. Then the heat shield is ejected. After the parachute slow the spacecraft down to a sufficient degree, both they and the back aeroshell depart leaving just the rover and its jet pack.
Curiosity will employ a very unique method to touch down on Mars. What is essentially a jet-pack, called the SkyCrane will be used to allow the rover to hover in mid-air as it is lowered via cables to the ground. Photo Credit: Alan Walters/awaltersphoto.com
During the landing phase the “SkyCrane” comes alive with eight powerful hydrazine engines, each of which give Curiosity 800 pounds of thrust. Aerojet’s Redmond Site Executive, Roger Myers, talked a bit about this segment of the landing, considered by many to be the most dramatic method of getting a vehicle to the surface of Mars.
“Because of the control requirements for the SkyCrane these engines had to be very throttleable,” Myers said. “Keeping the SkyCrane level is a must, you must have very fine control of those engines to ensure stability.”
Although the SkyCrane is often highlighted as an aspect that will add complexity to MSL's mission - there are numerous systems that can cause an early end to the mission. Image Credit: NASA/JPL
If all has gone well up to this point, the Curiosity rover will be lowered the remaining distance to the ground via cables. Once contact with the Martian surface is detected, the cables are cut, the SkyCrane’s engines throttle up and the jet pack flies off to conduct a controlled crash (approximately a mile or so away from where Curiosity is located).
Every powered landing on Mars conducted in the U.S. unmanned space program has utilized Aerojet’s thrusters. The reliability of these small engines was recently proven – in a mission that is now almost three-and-a-half decades old.
Tucked in between the aeroshell and the heat shield, Curiosity is prepared to take the long trip to the Red Planet. Photo Credit: NASA/JPL
Voyager recently conducted a course correction some 34 years after it was launched – highlighting the capability of these thrusters to perform well after launch.
“Our engines have allowed missions to fly to every planet in the solar system and we are currently on our way to Mercury and Pluto,” Myers said. “When NASA explores the solar system – Aerojet provides the propulsion components.”
Hundreds of different components, provided by numerous contractors and sub-contractors all must work perfectly to ensure that the Mars Science Laboratory makes it safely to Mars. Photo Credit: Alan Walters/awaltersphoto.com
Mars Science Laboratory, launched three days ago on the morning of Saturday, November 26, is currently on its way to the Red Planet – a journey that will take nearly nine months. When it arrives the first week of August 2012, MSL will begin investigating the soil and atmosphere within Gale Crater, searching for the faintest hints of past life. And unlike the previous rovers which ran on solar energy, MSL will be nuclear-powered, generating its energy through the decay of nearly 8 pounds of plutonium-238. This will potentially keep the next-generation rover running for years… but what will fuel future exploration missions now that NASA may no longer be able to fund the production of plutonium?
Pu-238 is a non-weapons-grade isotope of the radioactive element, used by NASA for over 50 years to fuel exploration spacecraft. Voyagers, Galileo, Cassini… all had radioisotope thermoelectric generators (RTGs) that generated power via Pu-238. But the substance has not been in production in the US since the late 1980s; all Pu-238 has since been produced in Russia. But now there’s only enough left for one or two more missions and the 2012 budget plan does not yet allot funding for the Department of Energy to continue production.
Where will future fuel come from? How will NASA power its next lineup of robotic explorers? (And why aren’t more people concerned about this?)
Amateur astronomer, teacher and blogger David Dickinson went into detail about this conundrum in an informative article written earlier this year. Here are some excerpts from his post:
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When leaving our fair planet, mass is everything. Space being a harsh place, you must bring nearly everything you need, including fuel, with you. And yes, more fuel means more mass, means more fuel, means… well, you get the idea. One way around this is to use available solar energy for power generation, but this only works well in the inner solar system. Take a look at the solar panels on the Juno spacecraft bound for Jupiter next month… those things have to be huge in order to take advantage of the relatively feeble solar wattage available to it… this is all because of our friend the inverse square law which governs all things electromagnetic, light included.
Curiosity's MMRTG (about 15 inches high.) Credit: NASA / Frankie Martin
To operate in the environs of deep space, you need a dependable power source. To compound problems, any prospective surface operations on the Moon or Mars must be able to utilize energy for long periods of sun-less operation; a lunar outpost would face nights that are about two Earth weeks long, for example. To this end, NASA has historically used Radioisotope Thermal Generators (RTGs) as an electric “power plant” for long term space missions. These provide a lightweight, long-term source of fuel, generating from 20-300 watts of electricity. Most are about the size of a small person, and the first prototypes flew on the Transit-4A & 5BN1/2 spacecraft in the early 60’s. The Pioneer, Voyager, New Horizons, Galileo and Cassini spacecraft all sport Pu238 powered RTGs. The Viking 1 and 2 spacecraft also had RTGs, as did the long term Apollo Lunar Surface Experiments Package (ALSEP) experiments that Apollo astronauts placed on the Moon. An ambitious sample return mission to the planet Pluto was even proposed in 2003 that would have utilized a small nuclear engine.
A glowing cake of plutonium. (Department of Energy)
David goes on to mention the undeniable dangers of plutonium…
Plutonium is nasty stuff. It is a strong alpha-emitter and a highly toxic metal. If inhaled, it exposes lung tissue to a very high local radiation dose with the attending risk of cancer. If ingested, some forms of plutonium accumulate in our bones where it can damage the body’s blood-forming mechanism and wreck havoc with DNA. NASA had historically pegged a chance of a launch failure of the New Horizons spacecraft at 350-to-1 against, which even then wouldn’t necessarily rupture the RTG and release the contained 11 kilograms of plutonium dioxide into the environment. Sampling conducted around the South Pacific resting place of the aforementioned Apollo 13 LM re-entry of the ascent stage of the Lunar Module, for example, suggests that the reentry of the RTG did NOT rupture the container, as no plutonium contamination has ever been found.
Yet the dangers of nuclear power often overshadow its relative safety and unmistakable benefit:
The black swan events such as Three Mile Island, Chernobyl and Fukushima have served to demonize all things nuclear, much like the view that 19thcentury citizens had of electricity. Never mind that coal-fired plants put many times the equivalent of radioactive contamination into the atmosphere in the form of lead210, polonium214, thorium and radon gases, every day. Safety detectors at nuclear plants are often triggered during temperature inversions due to nearby coal plant emissions… radiation was part of our environment even before the Cold War and is here to stay. To quote Carl Sagan, “Space travel is one of the best uses of nuclear weapons that I can think of…”
Yet here we are, with a definite end in sight to the supply of nuclear “weapons” needed to power space travel…
Currently, NASA faces a dilemma that will put a severe damper on outer solar system exploration in the coming decade. As mentioned, current plutonium reserves stand at about enough for the Mars Science Laboratory Curiosity, which will contain 4.8kilograms of plutonium dioxide, and one last large & and perhaps one small outer solar system mission. MSL utilizes a new generation MMRTG (the “MM” stands for Multi-Mission) designed by Boeing that will produce 125 watts for up to 14 years. But the production of new plutonium would be difficult. Restart of the plutonium supply-line would be a lengthy process, and take perhaps a decade. Other nuclear based alternatives do indeed exist, but not without a penalty either in low thermal activity, volatility, expense in production, or short half life.
The implications of this factor may be grim for both manned and unmanned space travel to the outer solar system. Juxtaposed against at what the recent 2011 Decadal Survey for Planetary Exploration proposes, we’ll be lucky to see many of those ambitious “Battlestar Galactica” –style outer solar system missions come to pass.
Landers, blimps and submersibles on Europa, Titan, and Enceladus will all operate well out of the Sun’s domain and will need said nuclear power plants to get the job done… contrast this with the European Space Agency’s Huygens probe, which landed on Titan after being released from NASA’s Cassini spacecraft in 2004, which operated for scant hours on battery power before succumbing to the -179.5 C° temps that represent a nice balmy day on the Saturnian moon.
So, what’s a space-faring civilization to do? Certainly, the “not going into space” option is not one we want on the table, and warp or Faster-Than-Light drives a la every bad science fiction flick are nowhere in the immediate future. In [my] highly opinionated view, NASA has the following options:
Exploit other RTG sources at penalty. As mentioned previously, other nuclear sources in the form of Plutonium, Thorium, and Curium isotopes do exist and could be conceivably incorporated into RTGs; all, however, have problems. Some have unfavorable half-lives; others release too little energy or hazardous penetrating gamma-rays. Plutonium238 has high energy output throughout an appreciable life span, and its alpha particle emissions can be easily contained.
Design innovative new technologies. Solar cell technology has come a long way in recent years, making perhaps exploration out to the orbit of Jupiter is do-able with enough collection area. The plucky Spirit and Opportunity Mars rovers(which did contain Curium isotopes in their spectrometers!) made do well past their respective warranty dates using solar cells, and NASA’s Dawn spacecraft currently orbiting the asteroid Vesta sports an innovative ion-drive technology.
Push to restart plutonium production. Again, it is not that likely or even feasible that this will come to pass in today’s financially strapped post-Cold War environment. Other countries, such as India and China are looking to “go nuclear” to break their dependence on oil, but it would take some time for any trickle-down plutonium to reach the launch pad. Also, power reactors are not good producers of Pu238. The dedicated production of Pu238 requires either high neutron flux reactors or specialized “fast” reactors specifically designed for the production of trans-uranium isotopes…
Based on the realities of nuclear materials production the levels of funding for Pu238 production restart are frighteningly small. NASA must rely on the DOE for the infrastructure and knowledge necessary and solutions to the problem must fit the realities within both agencies.
And that’s the grim reality of a brave new plutonium-free world that faces NASA; perhaps the solution will come as a combination of some or all of the above. The next decade will be fraught with crisis and opportunity… plutonium gives us a kind of Promethean bargain with its use; we can either build weapons and kill ourselves with it, or we can inherit the stars.
Diagram of an RTG. (Source: The Encyclopedia of Science)
Thanks to David Dickinson for the use of his excellent article; be sure to read the full version on his Astro Guyz site here (and follow David on Twitter @astroguyz.) Also check out this article by Emily Lakdawalla of The Planetary Society on how the RTG unit for Curiosity was made.
“There are some people who legitimately feel like this is simply not a priority, that there’s not enough money and it’s not their problem. But I think if you try to step back and look at the forest and not just the individual trees, this is one of the things that has helped drive us to become a technological powerhouse. What we’ve done with robotic space exploration is something that people not just in the U.S., but around the world, can look up to.”
– Ralph McNutt, planetary scientist at Johns Hopkins University’s Applied Physics Laboratory (APL)
NASA's Mobile Launcher (ML) begins its long (and slow) trek to Launch Complex-39B at Kennedy Space Center in Florida. Photo Credit: Alan Walters/awaltersphoto.com
Video of Mobile Launcher on its move out to Launch Complex 39B courtesy of Alan Walters/awaltersphoto.com
CAPE CANAVERAL, Fla – NASA decided that its Mobile Launcher (ML) needed a bit of a shakedown cruise – so it took it on a trip to Launch Complex – 39B (LC-39B). Along the way it stopped and reviewed data as to how the massive tower fared as it lumbered along at the blistering pace of a mile-an-hour. This does not make for riveting must-see video – unless you speed it up.
In the roughly minute-long video the ML moves along at a (somewhat) faster pace. The ML is part of the space agency’s plans to return NASA to the business of space exploration once again. If all goes according to plan, the ML will be the platform used to launch NASA’s Space Launch System or SLS.
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As with so many aspects of space exploration, there is a type of art that flows from even the least aesthetic blocky components that are used to lift Heaven and Earth. For those with the right eye, even a metallic tower has a beauty all its own.
That is exactly what aerospace photographer Alan Walters does – find the path to let an object’s inner beauty shine through. The burly photographer has an artist’s eye and loves sharing the awe of all manners of space flight and spacecraft processing.
On Wednesday one of the most emotional aspects of the journey to the launch pad – was the resemblance of some of the images – to those shot during the Apollo era. This imagery could well be prescient as NASA is passing the responsibility of delivering crew and cargo to the International Space Station to commercial space firms as it turns its focus on launching crews to points beyond low-Earth-orbit.
In an image that is eerily similar to shots taken during the moonshots of the late 1960s and early 1970s NASA's Mobile Launcher moves out to Launch Complex-39B on Nov. 16, 2011. Photo Credit: Alan walters/awaltersphoto.com
The ML moved from next to Kennedy Space Center’s (KSC) Vehicle Assembly Building (VAB) to LC-39B to collect data from structural and functional engineering tests. Any relevant data that is gleaned from the journey will be used to modify the ML. The 355-foot-tall ML is being developed to support NASA’s exploration objectives.
“To be honest, I wasn’t expecting much from the move,” Walters said. “After the thing got moving, I began having Apollo flashbacks and I got more and more into photographing and getting video of this event. It made me hopeful about what we might be seeing fly out of Kennedy (Space Center) in the years to come.”
Spiraling upward into the sky, the Mobile Launcher rises some 355 feet into the air and could one day be the platform from which astronauts launch to visit other worlds. Photo Credit: Alan Walters/awaltersphoto.com
