WELCOME TO ASTEROID MISSION CONCEPT - SUITE two
. The RAMA Project: Converting Asteroid Into Spacecraft - Concept Study
. Asteroids: What And where?
. Rosetta: last Image taken shortly before impact onAsteroid 67P
. The Historical Mission: Asteroid Redirect Robotic & Crewed Missions
. INTRO to The RAMA Project - Converting Asteroid Into Spacecraft!
. INTRO to NASA OSIRIS-REx Mission
. Space Mining Just Got a Big BOOST
. Can We Mine Planet Mercury?
. BEPICOLOMBO Spacecraft Mission
. Can we Mining the Atmosphere of Mars?
. ISRU Propellant's Selection/Application
. Japan's Hayabusa 2 mission to Asteroid 1999 JU3
. BepiColombo mission to MERCURY
. OSIRIS-REx mission to Asteroid Bennu (1999 RG36)
. Juno's Spacecraft mission to JUPITER (intro)
. A look on the Future's Spacecraft Mission & on the Historic's discoveries from Mariner, Pioneers and many others
The OSIRIS narrow-angle camera aboard the Space Agency's Rosetta spacecraft captured this HomePage Image of comet 67P/Churyumov-Gerasimenko on September 30, 2016, from an altitude of about 10 miles (16 kilometers) above the surface during the spacecraft’s controlled descent. The image scale is about 12 inches per pixel and measures about 2,000 feet (614 meters) across.
Serious Planning for Asteroid Redirect Mission - Update
NASA has completed a review of its upcoming, first-of-its-kind Asteroid Redirect Mission (ARM) flight. ARM, scheduled to launch in 2021, will see the agency attempt to retrieve a boulder from the surface of a Near Earth Asteroid, place that boulder into lunar orbit, and test a potential planetary defense capability.
March 16, 2016 by Chris Gebhardt.
Liftoff of OSIRIS-REX
An Atlas V rocket lifts off Sept. 8, 2016, at Cape Canaveral Air Force Station for a Historic Step for the U.S. Space Program. The mission is to send NASA’s OSIRIS-REx spacecraft to RENDEZ-VOUS with Bennu Asteroid in 2018 and retrieve at least two ounces of surface material and return it to Earth for study in 2023.
NEW CONcept to defend earth
CAN WE TRANSFORM ASTEROID IN SPACECRAFT? THE RAMA PROJECT SAY YES... WITH SOME CONDITIONS. LEARN MORE AT SPACE ECONOMY
Funded by the NASA NIAC program, Made in Space Company had completed its Phase I study to potentially establish the concept of feasibility of using space manufacturing to convert asteroids into autonomous, mechanical spacecraft. Its Project named RAMA for Reconstituting Asteroids into Mechanical Automata, is designed to leverage future'advances of Additive Manufacturing (AM), in-situ Resource Utilization (ISRU) and In-Situ Manufacturing (ISM) to realize enormous efficiencies in repeated asteroid redirect missions. That revolutionary concept has been performed by a team of engineers with consultation of the Asteroid Mining Industry, Academia and NASA.
LEARN MORE JUST BELOW (YOUR RIGHT)
ROSETTA LAST IMAGE TAKEN SHORTLY BEFORE IMPACT
A new image of comet 67P/Churyumov-Gerasimenko was taken by the European Space Agency’s (ESA) Rosetta spacecraft shortly before its controlled impact into the comet’s surface on Sept. 30, 2016. Confirmation of the end of the mission arrived at ESA's European Space Operations Center in Darmstadt, Germany, at 4:19 a.m. PDT (7:19 a.m. EDT / 1:19 p.m. CEST) with the loss of signal upon impact. The final descent gave Rosetta the opportunity to study the comet's gas, dust and plasma environment very close to its surface, as well as take very high-resolution images.
Rosetta's last image of Comet 67P/Churyumov-Gerasimenko, taken shortly before impact, at an estimated altitude of 66 feet above the surface. Measures about 2.4 m, the image was taken with the OSIRIS wide-angle camera on 30 September and his scale is about 5 mm/pixel.
Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Last Update, 29 SEP 2017
THE ROSETTA TEAM JUST FOUND ONE FINAL IMAGE, HIDING IN THE DATA
ESA scientists have found one additional image from the Rosetta spacecraft hiding in the telemetry.
This new image was found in the last bits of data sent by Rosetta immediately before it shut down on the surface of Comet 67P/Churyumov–Gerasimenko last year.
A final image from Rosetta, shortly before it made a controlled impact onto Comet 67P/Churyumov–Gerasimenko on 30 September 2016.
Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
ASTEROIDS: WHAT AND WHERE?
Collectively, the asteroids represent a total of 3·1021 kg of material, equivalent to ~5% the mass of the Moon, or a single body ~1400 km across. The majority of this mass is contained within the ~900 km dwarf planet Ceres, and most of the remaining mass is distributed in the main belt between Mars and Jupiter.
It is nearly impossible to state any universal rule about asteroids, as their sheer number ensures that there will be exceptions to every rule. For example, even though the majority of asteroids are located in the main belt, a large number exist in Earth crossing orbits that make them much more accessible (and easier to detect) than the main belt population. These asteroids are collectively referred to as Near Earth Objects (NEOs) and are defined as any asteroid with a minimum orbital radius of <1.3 AU. Given their proximity to Earth, NEOs are the most heavily studied, and will likely be the first asteroids to be tapped for their resources.
Due to a continuous process of collision and accretion that began when our solar system formed, asteroid sizes have been smoothed out to follow a predictable power law. In general, an asteroid of any size is ~100 times more prevalent than an asteroid 10 times its own size. So if a given region of space can be seen to be populated by 100 asteroids with diameters >10 km, it is reasonable to assume that there are ~1,000,000 undetected asteroids in the same region with diameters >100 m. No comprehensive telescopic survey has yet been conducted with the ability to detect asteroids <100 m in diameter, and our knowledge of asteroids of this size is limited to the small population that has been detected when one makes a fortuitous close pass of Earth.
Are they made by what?
Asteroids formed from the same circumstellar cloud of gas and dust as the inner planets, so their bulk composition is generally similar to Earth. However, Earth’s larger mass and gravity has allowed its interior to remain hot and geologically active, concentrating various materials through processes that never took place on the asteroids.
Asteroids thus tend to be more homogeneous and undifferentiated than Earth. While Earth’s surface and interior show high differentiation and can be divided into layers and geological zones, a sample from one part of an asteroid is likely to be similar to every other part of the same asteroid.
This lack of differentiation offers both advantages and disadvantages for resource utilization. One advantage is that it makes characterization of an asteroid’s composition considerably easier. Unlike Earth, an asteroid’s composition is not a strong function of location, and any materials found on an asteroid’s surface are likely be present throughout the asteroid’s interior. A lack of differentiation also means that valuable materials that are locked up in inaccessible regions on Earth are within easy reach on asteroids. Metals like iridium, which on Earth are mostly dissolved deep in our iron core, are distributed uniformly throughout an asteroid. Rare platinum group metals can only be found on Earth in locations where geologic process have brought them near the surface. But on asteroids, they are likely distributed throughout the body, and can be naturally separated while mining for other minerals.
The disadvantage to this lack of differentiation is that much larger volumes of asteroid materials must be processed to yield the same quantity of resources. Mining on Earth is frequently a process of following veins where minerals are present in higher quantities than in the surrounding deposits; By contrast, mining on asteroids is likely to focus more on moving and processing large volumes of a uniformly low grade ore.
Medium sized asteroids (1-100 km in diameter) have sufficient gravity to adhere small rocks and regolith to their surface, but insufficient gravity to develop the internal pressure or heat required to melt or separate their interiors. Asteroids in this size range tend to resemble loose packed agglomerations with a porous structure. Mining material from these asteroids will require comparatively little breaking or mechanical processing, as an assortment of materials in a range of sizes is already available.
By contrast, small asteroids <100 m in diameter are more likely to be a single continuous body, as their surface gravity is too weak to hold on to anything loosely packed. The continuous nature of small asteroids is also evident from studies of their rotation rate. Small asteroids are regularly observed to be rotating rapidly enough that centrifugal force at their surface exceeds that of their gravity, implying that the body must have some internal cohesion in order to remain intact.
Knowledge of the period of revolution can be obtained by repeated observations of the asteroid and detecting cycles in its apparent magnitude, but knowledge of the asteroids diameter and mass cannot be known accurately without up close observations from a spacecraft. This method should thus be used with caution.
The mining techniques deployed on these small monolithic asteroids will be very different than those deployed on a medium asteroid, requiring the ability to break down large chunks before processing. This can be an advantage, as the monolithic structure can negate the need for support or reinforcement to brace the asteroid against acceleration.
Ground based observations are not able to resolve asteroids as anything other than point sources except during very close passes of Earth. The only way to infer an asteroid’s size from ground observations is by measuring the amount of light it reflects. Like with stars, this measurement is quantified with a photometric magnitude system, where a lower magnitude corresponds to a brighter source, and each step of -1 magnitude equates to a factor of 2.5 increases in the intensity of the source.
An asteroid’s apparent magnitude is not a simple function of its distance from the observer, but also of its phase angle (the angle between the sun, the asteroid and the Earth) and its albedo (the tendency of its surface to reflect light). Different asteroid types will have different surface coatings, which preferentially scatter light in different directions, further complicating the estimation of an asteroid’s size from its magnitude. Asteroids tend to have dark, non-reflective surfaces with albedo values of .04-.20, making them as dark as asphalt.
By convention, the absolute magnitude of an asteroid is defined as its apparent magnitude when it is at 1 AU from the Earth and from the Sun. A typical 50 m asteroid may have an absolute magnitude of ~26, illustrating the difficulty in detecting these small objects except when they are very close to Earth (typical limits on telescopes dedicated to asteroid surveys are 21-24, meaning a 50 m asteroid in a 1 AU orbit may not be detected until it is within 0.1-0.3 AU of Earth. This further highlights the distinction between proven and unproven resources in asteroid mining. Estimates of potential resources must be informed by the understanding that all asteroid surveys are partial surveys only.
Because the vast majority of asteroids are too dim to be detected except when they are close to Earth or at a favorable phase angle, asteroids can go several years after detection without being observed again. Asteroids in orbits with periods similar to Earth’s will only make close passes of Earth every few decades, complicating the process of re-acquiring them once they have been lost. The convention for discovery and identification of asteroids requires observing them on multiple passes (typically 4-5) before their orbit is sufficiently well characterized to not be lost again. Once an asteroid has met this threshold, it is assigned a unique discovery number (e.g. 2350751). Until then, each asteroid is referred to by its discovery year and a temporary letter code (e.g. 2002 AW).
The vast majority (>90%) of asteroids have yet to be observed a sufficient number of times for a precise orbital fix, so asteroids are most commonly referred to by the temporary discovery year and letter code.
Factors contributing to an asteroid’s apparent magnitude. An asteroid just outside of Earth’s orbit and at low phase angle will be almost fully illuminated, and physically closer, making it much easier to detect than one which is inside Earth’s orbit and far away. The absolute magnitude of an asteroid is defined as the apparent magnitude it would present if it were located 1 AU from both the Earth and Sun. Note how the asteroid may never actually occupy this position.
Physical Properties: Once an asteroid’s absolute magnitude H has been measured, and an estimate of its albedo α has been made (or assumed) an estimate of the asteroid’s diameter can be derived from the empirical relationship seen in Equation 3.
Very little additional information can be obtained beyond this from telescopic observations alone. If repeated observations can be taken frequently enough, it is possible to measure the small changes in brightness that occur as the asteroid rotates, thus providing a measurement of the asteroid’s spin rate and approximate shape. If the asteroid can be imaged in multiple color filters, an estimate of its composition and type can be made (though high-resolution spectral data is still required to confirm). Observations beyond position and magnitude are not commonly collected due to telescope time and cost constraints, so the sum total of all “known” information about an asteroid is often limited to its approximate orbit, and a very rough estimate of its size. Nothing can be known about its shape, mass, density or composition without additional observations. Next to diameter, the most important property of an asteroid is arguably its mass, which is impossible to measure from the ground. Until the asteroid is visited by a spacecraft, details like its mass can only be guessed at.
An estimate of an asteroid’s type and composition requires multiple measurements in multiple color bands, or detailed spectral data. No common database of asteroid spectra exists at the moment, but a rough taxonomy of asteroids has still been developed by matching available spectral data to identified meteorites found here on Earth. The two most common types are described below and shown in Table 1-1:
C-cadre: More common in the main belt, less common near Earth orbit. Characterized by a darker albedo, lower density, and a higher prevalence of organic compounds, water-ice and other volatiles.
S-cadre: The most common near Earth object type, but less common in the main belt. Characterized by a high albedo, and a stony/metallic composition with very little water-ice or volatiles.
The details of an asteroid’s composition can cover a wide range, even within a given type, and there is a large amount of overlap/ambiguity between types. Properties of various general asteroid types, and their relative abundances throughout the inner solar system are shown in Figure 1-6.
Asteroids, sometimes called minor planets, are rocky remnants left over from the early formation of our solar system about 4.6 billion years ago.
Most of this ancient space rubble can be found orbiting the sun between Mars and Jupiter within the main asteroid belt. Asteroids range in size from Vesta - the largest at about 329 miles (530 kilometers) in diameter - to bodies that are less than 33 feet (10 meters) across. . The total mass of all the asteroids combined is less than that of Earth's Moon.
Editor's note: Even with more than one-half million asteroids known (and there are probably many more), they are still much more widely separated than sometimes seen in Hollywood movies: on average, their separation is in excess of 1-3 million km (depending on how one calculates it).
A mosaic of the best views of the giant asteroid Vesta.
The Galileo spacecraft found asteroids can have moons.
A snapshot of near-Earth asteroids.
This image, taken by NASA's Near Earth Asteroid Rendezvous mission in 2000, shows a close-up view of Eros, an asteroid with an orbit that takes it somewhat close to Earth. NASA's Spitzer Space Telescope observed Eros and dozens of other near-Earth asteroids.Image Credit: NASA/JHUAPL
Most asteroids are irregularly shaped, though a few are nearly spherical, and they are often pitted or cratered. As they revolve around the sun in elliptical orbits, the asteroids also rotate, sometimes quite erratically, tumbling as they go. More than 150 asteroids are known to have a small companion moon (some have two moons). There are also binary (double) asteroids, in which two rocky bodies of roughly equal size orbit each other, as well as triple asteroid systems.
The three broad composition classes of asteroids are C-, S-, and M-types. The C-type (chondrite) asteroids are most common, probably consist of clay and silicate rocks, and are dark in appearance. They are among the most ancient objects in the solar system. The S-types ("stony") are made up of silicate materials and nickel-iron. The M-types are metallic (nickel-iron). The asteroids' compositional differences are related to how far from the sun they formed. Some experienced high temperatures after they formed and partly melted, with iron sinking to the center and forcing basaltic (volcanic) lava to the surface. Only one such asteroid, Vesta, survives to this day.
Jupiter's massive gravity and occasional close encounters with Mars or another object change the asteroids' orbits, knocking them out of the main belt and hurling them into space in all directions across the orbits of the other planets. Stray asteroids and asteroid fragments slammed into Earth and the other planets in the past, playing a major role in altering the geological history of the planets and in the evolution of life on Earth.
Scientists continuously monitor Earth-crossing asteroids, whose paths intersect Earth's orbit, and near-Earth asteroids that approach Earth's orbital distance to within about 45 million kilometers (28 million miles) and may pose an impact danger. Radar is a valuable tool in detecting and monitoring potential impact hazards. By reflecting transmitted signals off objects, images and other information can be derived from the echoes. Scientists can learn a great deal about an asteroid's orbit, rotation, size, shape, and metal concentration.
Several missions have flown by and observed asteroids. The Galileo spacecraft flew by asteroids Gaspra in 1991 and Ida in 1993; the Near-Earth Asteroid Rendezvous (NEAR-Shoemaker) mission studied asteroids Mathilde and Eros; and the Rosetta mission encountered Steins in 2008 and Lutetia in 2010. Deep Space 1 and Stardust both had close encounters with asteroids.
In 2005, the Japanese spacecraft Hayabusa landed on the near-Earth asteroid Itokawa and attempted to collect samples. On June 3, 2010, Hayabusa successfully returned to Earth a small amount of asteroid dust now being studied by scientists.
NASA's Dawn spacecraft, launched in 2007, orbited and explored asteroid Vesta for over a year. Once it left in September 2012, it headed towards dwarf planet Ceres, with a planned arrival of 2015. Vesta and Ceres are two of the largest surviving protoplanet bodies that almost became planets. By studying them with the same complement of instruments on board the same spacecraft, scientists will be able to compare and contrast the different evolutionary path each object took to help understand the early solar system overall.
Main asteroid belt: The majority of known asteroids orbit within the asteroid belt between Mars and Jupiter, generally with not very elongated orbits. The belt is estimated to contain between 1.1 and 1.9 million asteroids larger than 1 kilometer (0.6 mile) in diameter, and millions of smaller ones. Early in the history of the solar system, the gravity of newly formed Jupiter brought an end to the formation of planetary bodies in this region and caused the small bodies to collide with one another, fragmenting them into the asteroids we observe today.
Trojans: These asteroids share an orbit with a larger planet, but do not collide with it because they gather around two special places in the orbit (called the L4 and L5 Lagrangian points). There, the gravitational pull from the sun and the planet are balanced by a trojan's tendency to otherwise fly out of the orbit. The Jupiter trojans form the most significant population of trojan asteroids. It is thought that they are as numerous as the asteroids in the asteroid belt. There are Mars and Neptune trojans, and NASA announced the discovery of an Earth trojan in 2011.
Near-Earth asteroids: These objects have orbits that pass close by that of Earth. Asteroids that actually cross Earth's orbital path are known as Earth-crossers. As of June 19, 2013, 10,003 near-Earth asteroids are known and the number over 1 kilometer in diameter is thought to be 861, with 1,409 classified as potentially hazardous asteroids - those that could pose a threat to Earth.
How Asteroids Get Their Names
The International Astronomical Union's Committee on Small Body Nomenclature.is a little less strict when it comes to naming asteroids than other IAU naming committees. So out there orbiting the sun we have giant space rocks named for Mr. Spock (a cat named for the character of "Star Trek" fame), rock musician Frank Zappa, regular guys like Phil Davis, and more somber tributes such as the seven asteroids named for the crew of the Space Shuttle Columbia killed in 2003. Asteroids are also named for places and a variety of other things. (The IAU discourages naming asteroids for pets, so Mr. Spock stands alone).
Asteroids are also given a number, for example (99942) Apophis. The Harvard Smithsonian Center for Astrophysics keeps a fairly current list of asteroid names.
- 1801: Giuseppe Piazzi discovers the first and largest asteroid, Ceres, orbiting between Mars and Jupiter.
- 1898: Gustav Witt discovers Eros, one of the largest near-Earth asteroids.
- 1991-1994: The Galileo spacecraft takes the first close-up images of an asteroid (Gaspra) and discovers the first moon (later named Dactyl) orbiting an asteroid (Ida).
- 1997-2000 : The NEAR Shoemaker spacecraft flies by Mathilde and orbits and lands on Eros.
- 1998: NASA establishes the Near Earth Object Program Office to detect, track and characterize potentially hazardous asteroids and comets that could approach Earth.
- 2006: Japan's Hayabusa becomes the first spacecraft to land on, collect samples and take off from an asteroid.
- 2006: Ceres attains a new classification -- dwarf planet -- but retains its distinction as the largest known asteroid.
- 2007: The Dawn spacecraft is launched on its journey to the asteroid belt to study Vesta and Ceres.
- 2008: The European spacecraft Rosetta, on its way to study a comet in 2014, flies by and photographs asteroid Steins, a type of asteroid composed of silicates and basalts.
- 2010: Japan's Hayabusa returns its asteroid sample to Earth.
- 2010: Rosetta flies by asteroid Lutetia, revealing a primitive survivor from the violent birth of our solar system.
- 2011-2012: Dawn studies Vesta. Dawn is the first spacecraft to orbit a main-belt asteroid and continues on to dwarf planet Ceres in 2015.
Credit: Fox News Published on Jun 8, 2016 SUBSCRIBE 727K Four4Four Science: NASA is funding a concept that will turn asteroids into spaceships so that we can mine them. Will it work?
Credit: SETI Institute Streamed live, Speaker: Michael Busch, SETI Institute.
Like RAMA Project, Automaton Rover for VENUS Mission Will be built with mechanicals' parts to resist at High Temperature of 460°C and where the Corrosion resistance is a more nuanced problem considering the high pressure (90 bar) of the environment, i.e. CO2 is near its supercritical state.
Credits: NASA JPL, Johathan Sauder, Jessie Kawata, Lori Nishikawa, Evan hilgemann, Katie Stack, Aaron Parness, Michael Johnson
NEW CONCEPT TO PROTECT EARTH
CAN WE TRANSFORM ASTEROID IN SPACECRAFT?
RAMA ARCHITECTURE CONCEPT OF THE ASTEROID SPACECRAFT
The purpose of the RAMA spacecraft is to leverage a small amount of mass and equipment delivered to the asteroid by a Seed Craft, and use it to return a larger mass of asteroid raw materials to cis-lunar space. To accomplish this, the RAMA craft requires all the functions of a conventional interplanetary spacecraft, subject to the constraints that they be 1) Manufactured from materials available on the asteroid, 2) Manufactured on/by equipment available on the Seed Craft.
CREATING SPACECRAFT FROM MECHANICAL SYSTEMS
Mechanical and analog devices have been in existence for centuries. Examples of mechanical computing devices date back to 200 BC and were used as navigational instruments in the early days of spaceflight before being superseded by electrical computers
The Antikythera mechanism – An ancient analog computer designed to predict astronomical positions and eclipses. Dated to 205 BC.
Additionally, research and development in this field has led to analog based 3D printers that require no power or electronics to manufacture a pre-designed object.
NASA NIAC has funded work to JPL under the AREE project (Automaton Rover for Extreme Environments) to develop a Venus rover made entirely of mechanical subsystem capable of surviving the harsh environment on the Venus surface.
The RAMA mission class also represents a desirable case for mechanical subsystems. Propulsion systems to move 100-meter asteroids are too large to launch, but can be built in-situ as mechanical mass drivers; flywheels for attitude control are too heavy to launch, but could be constructed within an asteroid to control its spin rate and store energy. It is also possible to create mechanical computation devices for spacecraft that could perform basic avionics-style routines. For missions that require independence from Earth, with no supply of Earth made electronics, the creation of basic mechanical computers may serve as an alternative.
RAMA FUNCTIONAL BLOCK DIAGRAM
At the heart of the mechanical spacecraft is a 3D printed analog computer that operates on a series of simple gears. The computer is powered by a store of potential energy found in 3D printed springs and flywheels. Mission objectives for the mechanical spacecraft will be fairly basic in nature requiring simple GNC. Flywheel gyros can be 3D printed and will keep the spacecraft on course by feeding momentum data into the analog computer which subsequently commands the propulsion system to propel asteroid materials and impart course corrections.
Upon asteroid rendezvous, the RAMA Seed Craft analyzes the asteroid, and begins effectively organizing available in-situ resources. The asteroid is broken down and materials are stockpiled as manufacturing feedstocks, as well as viable “waste” mass for propellant.
For the remainder of this report, it will be assumed that only the four most mass intensive systems of the RAMA craft (propulsion, structures, power storage and attitude control) must be built from asteroid materials.
THE SEED CRAFT
The Seed Craft shown in Figure 2-6, is a more conventional robotic interplanetary vehicle than the RAMA asteroid spacecraft. It contains a high performance low thrust ion engine, along with advanced robotic manufacturing capabilities to produce components of the RAMA vehicle from asteroid feedstocks. The extent of these manufacturing capabilities depends on the target asteroid.
The Seed Craft is designed around a single common spacecraft bus, incorporating the bare minimum of features required for every mission (propulsion, power distribution and regulation, communication, ADCS etc.) Specific manufacturing modules are then added to the Seed Craft bus to provide the required capabilities for converting a give asteroid. With prior knowledge of the size and composition of the asteroid, the Seed Craft can be fitted with the required manufacturing modules, and fitted with a correctly sized power system before departing cislunar space.
Each module is serviced by a common robotics system, which runs along the length of the interior of the spacecraft. Robotic manipulators are free to traverse the length of the track, transferring materials from one operation to another, and performing maintenance as required. The entire interior of the spacecraft remains unpressurized, allowing the manufacturing operation to take place free of atmospheric contamination.
The methods used to provide each required spacecraft capability depend on the size of the asteroid and the types of materials available.
Schematic of the Seed Craft Architecture. A modular solar electric propulsion system attached to a common bus. Ahead of the bus are various modules for performing specific tasks required at the asteroid. The module is serviced by a common robotics traverse for transporting materials between operations.
While rare metals like platinum and palladium are available in the asteroids, the true value of asteroid resources does not come from the presence of valuable trace materials. The value of the asteroids comes from the availability of common materials without the need to ship them from Earth.
Bulk materials, if available in space, will be exploited in space, with launch capacity from Earth being reserved for complex equipment and trace materials that cannot be obtained without Earth’s complex industrial base.
Asteroids thus contain abundant supplies of iron/nickel (present in Earth’s core) silicates and oxides (present in Earth’s mantle) and water-ice and other volatiles (present on Earth’s surface). These asteroid resources can be combined to produce effectively anything that a maturing space civilization requires.
The range of finished products and required processes available on a C-type asteroid. The prevalence of organics and volatiles leads to the exclusion of metal based manufacturing methods in favor of polymer structures and chemical propulsion systems. Adapted from J.L Lewis “Mining the Sky”, Figure IX2.
Even limited to these options, the C-type asteroid has the materials to produce high performance rocket propellant, which can be used to propel the RAMA spacecraft to new locations. The availability of polymers also permits composite structures to be manufactured along with the crushed rock and regolith, forming a composite material with excellent tensile and compressive strength.
Manufacturing techniques on the M-type asteroid would employ methods such as the carbonyl based Mond process and powder sintering methods to produce strong metallic structures. Propulsion options are much more limited, but one possibility would be the use of surplus metal to produce an electromagnetic cannon powered by locally manufactured photovoltaics.
Additive manufacturing technologies provide unique opportunities for the S-type asteroids. For example, additive manufacturing represents an instance of the fully autonomous robotic operations required by Step 5) Excavating. For manufacturing complex metallic parts without the support of a planet scale industrial base, additive manufacturing also provides an alternative to the Mond Carbonyl process. It is for these reasons that the current study focuses on the S-type asteroid for RAMA mission design.
S-TYPE ASTEROID MISSION ASSESSMENT
S-type asteroids are the most difficult case for the RAMA system, as they present the tightest constraint on available materials. The problem is one of propellant availability. C-type asteroids contain volatiles which are useful as propellant in a LOX-H2 or thermal water rocket, but S-type asteroids contain almost no water or organics, and the chemical compounds that make up the bulk of their mass are bound up in the form of inert oxides and rocks. This lack of chemical propellant option is partially offset by two advantages:
1) S-type asteroids contain higher proportions of Iron/Nickel, which is useful for local manufacturing and for reinforcing the asteroid.
2) S-type asteroids represent a higher fraction of near earth asteroids, and are generally easier to reach and return from.
Turning an S-type asteroid into a self-propelled spacecraft requires separating the valuable metals, and employing the less valuable silicate rocks as propellant. Due to the chemically inert nature of silicates, the most direct option available would be some form of mechanical propulsion, such as a sling.
Compared to chemical or ion propulsion, the effectiveness of a mechanical system would be limited. Regardless of composition or design, the mass efficiency of any propulsion system is defined exclusively by the exhaust velocity that it is able to produce in its propellant.
THE FAR END OF THE SPECTRUM – ASTEROID 2009 UY19
Asteroid 2009 UY19 is an S-type asteroid with an estimated diameter of 50-150m. UY19 will require nearly a decade of Seed Craft conversion in-situ to be ready for its mission to Earth-Moon L5.
The asteroid 2009 UY19 was discovered during a close flyby of Earth in October 2009, and makes periodic close passes of the Earth every 29 years. During these passes, it comes within a few million km (~10 Lunar Distances) of Earth, and the next pass in 2039 requires a ΔV of only 437 m/s to be diverted towards the Earth-Moon L5 point.
The orbital parameters of 2009 UY19 are shown in Table 3-15.Table 3-15: Orbital Parameters of 2009 UY192009 UY19 Asteroid OrbitSemi-major axis 1.02361 AU
Eccentricity 0.030796 -Inclination 9.05 degPeriod 1.036 yearsSynodic Period 29.07 years2009 UY19 Assumed Physical PropertiesType SAlbedo 0.26Diameter (m) 54Mass (kg) 2.3E+08Volume (m^3) 8.5E+04Density (kg/m^3) 2700
With the physical dimensions of the asteroid fixed, it is possible to estimate the materials available at the asteroid for constructing the RAMA spacecraft components. Under the standard composition model assumed by Rock Finder, the composition breakdown for UY19 is shown in Table 3-17.
Volume Fraction Diameter Equivalent*(m)Rock, Olivine (Mg,Fe)2SiO4 33.75% 38Rock, Orthopyroxene (Mg,Fe)2Si2O6 30.54% 37Iron 5.14% 20Nickel 2.21% 15
*The equivalent diameter of the component if collected into a single mass
Seed Craft Loadout
With no known sources of volatiles at UY19, the Seed Craft is customized for metal working and stone mining. No chemical processing equipment is included; instead the Seed Craft is loaded with four modules containing the following equipment:
1) Optical mining rig, containing a bank of one hundred 10kW lasers and a collection inlet, capable of spalling and collecting asteroid material at a rate of ~.5 kg/s.2) 5kW furnace for smelting and electromagnetically separating iron/nickel from rock.3) 5000 kg of alloying elements and equipment for producing high strength steel.4) A die extruder for extruding high strength steel into a circular beam 16 cm in diameter.5) A 750 kg electromagnetic bearing assembly for permanent installation on the asteroid.
The mission was designed by taking into account the closest approach windows for UY19 and then backing out each stage of the mission based on time from launch estimates.
UY19 Mission Timeline
The Seed Craft is boosted away from its base in cislunar space on a trajectory to intercept the asteroid. It ignites its 60-kW solar electric propulsion system 4 months later, affecting a rendezvous with UY19 0.32 years after launch. After 2-4 days orbiting the asteroid and mapping details of its mass distribution and gravity, it docks with UY19 along the asteroid’s spin axis, and anchors itself to the surface. The Seed Craft is now effectively part of the asteroid, and continues with it out of cislunar space. The Seed Craft then reconfigures itself for operations on the asteroid, deploying a group of independent robots to assist with securing the Seed Craft, removing obstructions, and any precision work that is required during the process. The full capacity of the Seed Craft’s four 27x34m solar arrays is deployed, providing the full 4 MW of solar power required to convert the asteroid into the RAMA spacecraft.
With its assumed composition and size, gravity at the asteroid’s surface is only .00002 g’s (~2 um/s2). The asteroid is thus likely to be a single monolithic piece, as any loosely bound components would have escaped the asteroid long ago. The lack of gravity and the cohesive nature of the asteroid will make mechanical excavation very difficult. Optical mining methods have been previously studied as ways of overcoming both difficulties in mining C-type asteroid by Sercel et al.  With a 10kW Optical Mining system operating at a temperature of 1000K, an excavation rate of ~5 mm3/min of material per W of power was observed (Figure 3-13). By directing the full power of the Seed Craft’s solar array to the optical mining system and operating at the higher temperature required to decompose stone and metal, an excavation rate of ~200 cm3/s can be expected.
The resulting debris from the mining site are lost to space until the Seed craft has bored a hole deep enough to insert the mining module into the asteroid, forming a closed cavity to prevent the loss of more debris. The material is then directed to an inlet adjacent to the optimal mining rig, where it is collected and conveyed away from the mining site to be purified and smelted.
The melted rock is allowed to cool in measured batches (“shots”) 18 cm in diameter. By cooling them in the presence of an electromagnetic field, they are left with a remnant magnetic field that makes them cohere to each other magnetically, and to the walls of the asteroid. These 18 cm shots will be used as the propellant for the mechanical propulsive system, and are packed around the wall of the ever-growing interior of the asteroid.
Figure 3-14: Schematic of the RAMA conversion process. The schematic shows the inside elements of the Seed Craft while manufacturing on the asteroid. The process of optically hollowing out the interior of the UY19 takes 8 years, producing a new shot every 17 seconds. Figure 3-15 shows the concept of the Seed Craft conversion of UY19 into the asteroid spacecraft, and Figure 3-14 shows a more detailed depiction of the Seed Craft operations on the asteroid. For the first decade of this process, a small fraction of the iron and nickel extracted from the material is not returned to the interior of the asteroid or embedded in the shots, but is separated and combined with the carbon and other alloying elements from the Seed craft to produce high strength steel. The steel is extruded through a die out through radial bore holes in the asteroid excavated by the robots until it extends 40 m in length.
The RAMA Architecture for the S-type asteroid 2009 UY19.
These “slings” are used for the main component of RAMA’s propulsion system. Rock Finder is capable of computing the sling performance characteristics and sizing as shown in Figure 3-16, Figure 3-17 and Figure 3-18. The base of each sling is firmly anchored to the interior of the asteroid. A series of 16 slings are extruded at equally spaced intervals around the asteroid. While the amount of material consumed in their production is large, (300 mT of materials to produce 80 mT of metal) it is small compared to the amount of material required to produce the shots. The minimal ability to extrude 29 kg (220 mm of beams) per day would take less than a year to finish. After that, metal is available to reinforce the interior of the asteroid, provide scaffolding for the robots, or reduced into a powder for joining and reinforcement via laser engineered net shaping with the mining lasers. After 8 years, when the asteroid is ~50% hollowed out, the 750 kg electromagnetic bearing assembly1 is detached from the Seed Craft and transported by the robots to the opposite interior of the asteroid. The base is welded to the interior wall, with its drive axis parallel to the spin axis of the asteroid. As construction continues, surplus iron and nickel from the smelter are combined with the remaining alloying elements from the Seed Craft to produce Inconel powder. Under robotic control using the Laser Engineered Net Shaping (LENS) technology from the manufacturing trade study in section 3.4.2, the powder is additively sintered radially outward from the electromagnetic bearing system, allocating the remaining metal composition of the asteroid into a single mass of metal, mounted on the electromagnetic bearing. The RAMA craft now has a crude mechanical spin stabilization and energy storage system.
The completed RAMA spacecraft en route to cislunar space.
Construction of the RAMA spacecraft is now complete (Figure 3-19). During manufacturing, the Seed Craft has gradually used its own propulsion system to stabilize and orient the asteroid’s spin axis in the correct direction. The system must now wait for the Earth return window to open. The Seed Craft stows its solar panels to protect them from debris, powers down its manufacturing systems, and waits 13 years for the return window to open. During this time, it periodically reawakens to perform status checks and remote sensing operations on any other targets the asteroid may pass close to.
One month before the window opens, the Seed Craft wakes up, and redeploys its power systems. It now applies the power from the 4 MW photovoltaics (previously used to power manufacturing operations) directly to the motors in the flywheels. This power is applied for 25 days, at the conclusion of which, the two flywheel are spinning at ~4000 rpm (their approximate material limit) and have stored ~1 GJ of energy, the amount of energy required to return the asteroid to Earth. Slightly charging one flywheel over the other imparts a greater rotation to the reinforced asteroid shell, producing significant artificial gravity at the surface of the asteroid, further adhering the shots up against the interior of the asteroid and up against electromechanical exit ports bored by the robots.
Finally, the Seed Craft uses its own propulsion system to provide a series of forward “kicks” to the asteroid. These kicks impart no significant ΔV, but are properly timed to match the fundamental frequency of the 16 extended slings protruding from the asteroid. The slings begin to oscillate back and forth, and after 3 days of continuous kicks, the slings are rocking back and forth with a high enough amplitude to be bend all the way back to the asteroid’s surface. The slenderness ratio of the slings (250:1) is large enough to remain fully elastic when bent this far, allowing it to continue to oscillate like a pendulum with only thermal losses. The Seed Craft, its decades long task complete, disengages from the asteroid and departs for its next target.
The slings, once set in motion, oscillate at a period of 2.1 seconds, and at the peak of their swing, the tips are travelling at 312 m/s, achieving the theoretical maximum velocity of the material (Figure 3-20). At the extreme of each swing, the tip of the sling passes close to the exit ports near the asteroid’s equator, where extremely strong rare Earth magnets on the tip of each sling adhere to a single 10 kg shot. The strength of the permanent magnet on the tip and the remnant magnetism if the shot is calibrated such that the adhesion strength is exceeded exactly at the full extension of the swing, where the centrifugal force is maximized, hurling the shot astern of the asteroid at 312 m/s, and imparting a small but nontrivial 13 microns/sec ΔV onto the asteroid. At full “throttle”, with all slings operating, the asteroid accelerates at a constant 11 micro-gs.
The movement of the RAMA spacecraft. The fluctuations of the sling arms back and forth would make the movement of the RAMA spacecraft look similar to a jellyfish swimming through the ocean currents.
This low impulse maneuver persists for 27 days. Each shot carries away a small fraction (0.55%) of the sling’s energy with it. Over time, this loss will cause the slings to oscillating through a smaller arc and the asteroid to spin at a slower rate. To compensate for this loss of energy, the flywheels, which have remained spinning since they were charged by the Seed Craft, are slightly braked each time the slings reload, imparting a slight transfer of angular momentum to the asteroid itself, and thus to the swing arms.
This places the asteroid on an intercept path to Earth-Moon L5, where it is intercepted 249 days later after a lunar flyby by a cislunar tug. The asteroid at this point is considerably lighter (34,000 mT vs 230,000 mT) and the returned material is considerably “purer”, as 90% of the asteroids worthless mass (its stone) has been ejected as propellant. The remaining mass is in the form of a pure metal flywheel and a hollow reinforced shell approximating the original shape of the asteroid, with an average wall thickness of ~4 m. The 30-year RAMA mission is complete, having delivered the mass equivalent of ~85 International Space Stations to the Earth-Moon L5 location.
CREDIT & SOURCE: MADE IN SPACE, NIAC PHASE I FINAL REPORT, PROJET RAMA: RECONSTITUTING ASTEROIDS INTO MECHANICAL AUTOMATA, 2017.