. Space Mining Just Got a Big BOOST

. Can We Mine Planet Mercury?

. BEPICOLOMBO Spacecraft's Mission

. Can we Mining the Atmosphere of Mars?

. ISRU Propellant's Selection/Application 

 
 

Credit: SpaceRef

Note: Highlights from the NASA's Fifth Annual NASA Robotic Mining Competition. The competition is for university-level students to design and build a mining robot that can traverse the simulated Martian chaotic terrain, excavate Martian regolith and deposit the regolith into a Collector Bin within 10 minutes. Video is courtesy NASA Edge.

 
 

ASTEROID MISSIONS

 
 
 
 

 
 

SPACE MINING JUST GOT A BIG BOOST

The U.S. Congress' passage of a bill that allows American companies to own and sell materials they extract from the moon, asteroids or other celestial bodies should help spur the development of off-Earth mining, representatives of the nascent industry say.

CAN WE MINE THE PLANET MERCURY?

Previous missions on Mercury

The first spacecraft visiting Mercury was Mariner 10, launched Nov 1973 from Cape Canaveral, USA. In fact, this vehicle was the first to visit not only Mercury, but also Venus in a single mission.

That spectacular Spacecraft was also the first to use gravity-assist to change its flight path, to return to its target after an initial encounter and, to use the pressure of the sun on its solar panels and high-gain antenna for attitude control.

The primary goal of Mariner 10 was to study the atmosphere, the surface, and the physical characteristics of Mercury.

Mariner 10 flew past Mercury three times in total. Owing to the geometry of its orbit — its orbital period was almost exactly twice Mercury's — the same side of Mercury was sunlit each time, so it was only able to map 40-45% of Mercury's surface, taking over 2800 photos. It revealed a more or less moon-like surface. Globally, it contributed enormously to our understanding of the planet, whose surface had not been successfully resolved through telescopic observation.

The second american spacecraft, MESSENGER,was a scientific investigation of the planet, the least explored of the terrestrial rocky planets, that also included Venus, Earth and Mars.

MESSENGER lifted off from Cape Canaveral Air Force Station on August 3, 2004. It matched Mercury's orbit with a series of flybys of Earth, Venus and Mercury, using gravity to adjust its path each time. Three Mercury flybys, which included photographing and measurements of the planet's previously unseen side, provided information critical to the planning and carrying out of the orbital study of the innermost planet.

MESSENGER passing 12-month orbit covers two Mercury solar days, while, moon to moon, one day is equal to 176 Earth days. During the first day, the spacecraft obtained a global mapping from its different instruments and, in the second day, the focus was on science investigations.

Credit: NASASolarSystem

The robotic spacecraft MESSENGER has run out of fuel. With no way to make major adjustments to its orbit around the planet Mercury, the probe will smash into the surface at more than 8,750 miles per hour (3.91 kilometers per second). The impact will add a new crater to the planet’s scarred face that engineers estimate will be as wide as 52 feet (16 meters).

What we know about Mercury

Mercury is the closest planet to the Sun with a perihelion of 46,000,000 km and an aphelion of nearly 70,000,000 km.

The high temperature, high heat flux environment at Mercury and the tenuous surface emanations of several major chemical species such sodium pose some challenges to long term human visits. Permanently shadowed craters offer a valuable niche for longer-term human visits and planetary bases. Such craters offer cryogenic temperatures while the Sun-facing surface is at a temperature of 590 to 725 K. The north Polar Regions of Mercury have been identified as a likely location for such permanently shadowed craters. Water ice is also likely to be in these craters, further aiding and assisting any human exploration(s). Short exploratory missions can be accomplished with hopping ascent descent vehicles from the base at the shadowed crater.

Figure at the right shows locations of the shadowed craters. The figure below depicts the temperatures that would exist in and near the craters. The crater could accommodate a small base or at least an initial landing site. The lander’s temperature could stay within the nominal operating temperatures of traditional spacecraft. The temperature distribution in the crater would allow construction of the base at the warmer side of the crater and then the frozen volatiles would be extracted with cryogenic mining machines.

Permanently shadowed craters in Mercury’s north polar region.

In resume, mining Mercury will be possible but this is Challenging . The future Mission to Mercury with the BepiColombo Spacecraft will answer at many questions about its magnetic field, subsurface/surface and atmosphere. 

Temperature ranges outside and inside permanently shadowed craters .

BEPICOLOMBO MISSION TO MERCURY

BepiColombo comprises a carrier spacecraft, known as the Mercury Transfer Module (MTM), and two separate orbiters. ESA is building the Mercury Planetary Orbiter (MPO), while the Japanese space agency, JAXA, is contributing the Mercury Magnetospheric Orbiter (MMO). Once they enter orbit around the planet, they will carry out the most comprehensive exploration of Mercury and its environment ever undertaken.

Scheduled for launch in October 2018, BepiColombo will be carry by the spacecraft Mercury Transfer Module (MTM) for almost seven years to reach its target. The MTM will traveling with the Mercury Planetary Orbiter (MPO) made by the Europeen Sppace Agency, ESA, and the Mercury Magnetospheric Orbiter (MMO)from the Japanese space agency, JAXA. Once they enter orbit around the planet, they will carry out the most comprehensive exploration of Mercury and its environment ever undertaken.

Mercury Planetary Orbiter, MPO. CREDIT: ESA

On the left, the Mercury Magnetospheric Orbiter, MMO. On the right, the Mercury Transfer Module. CREDIT: ESA

The carrier spacecraft MTM will be driven by a highly efficient, low thrust, electric propulsion system that will steadily propel it along a series of arcs around the Sun. The BepiColombo will return to Earth's vicinity in April 2020, fly past Venus in 2020 and 2021, and then receive six gravity assists from Mercury itself between 2021 and 2025. Once the spacecraft's speed has been slowed sufficiently by these flybys' manoeuvres, the MTM will be jettisoned and BepiColombo will be captured by Mercury's gravity in December 2025.

In the Mercury'orbit, MPO will use its chemical propulsion thrusters to go lower. Once done, the European and Japanese craft are deployed in separate orbits to begin their missions for one Earth year (4 Mercury years), with the option of a one year extension.

Flying in a 480 km × 1,500 km polar orbit, the MPO's 11 instruments will concentrate on the planet's surface and internal composition. The payload will consist of two cameras for high-resolution imaging and a suite of spectrometers designed to reveal the surface composition, search for water ice, and analyse Mercury's exosphere.

A laser altimeter will measure the surface morphology, while data from the dual band radio science experiment and an accelerometer will measure the gravity field with great accuracy in order to better estimate the distribution of mass within the planet and to study relativistic effects.

The smaller, octagonal MMO will observe the planet's magnetic field and its interactions with the solar wind from a highly elliptical, 590 × 11,640 km polar orbit. As it spins 15 times per minute, four wire antennas (each 15 m in length) will be used to make electric field and radio wave measurements, with two 5 m masts for magnetic field measurements.

By the end of the BepiColombo mission, scientists will not only have an-depth understanding of the little iron world, but also have a mass of data that will help them to unravel how Earth and its planetary neighbours formed some 4.5 billion years ago.

In space exploration, In-Situ Resource Utilization (ISRU) is the use of resources found or manufactured on other astronomical objects as the Moon, Mars, Asteroids or others, to further the goals of a space mission. 

The ability to produce propellant via In-Situ reduces Exploration Vehicle sizes, Propellant carry requirement by 50% and its tank diameter and length, as well as the number of launches or Space Travel.

Can we Mining the Atmosphere of Mars?

A study (phase 1) from NASA Innovative Advanced Concepts (NIAC) say it is really possible. This Mars Molniya Orbit Atmospheric Resource Mining report elaborate an innovative and feasible concept for a reusable Mars space transportation system that, without ever relying on propellant transported from Earth, can repeatedly launch and land on Mars. To do that, it can use propellant and electrical energy generated on orbit via plasma-harnessing, scooping, and ram-compressing the 95% CO2 Martian atmosphere, as well as the indigenous resources on the surface of Mars (CO2, H2O). Instead today's EDL technology, which limit to approximately 1-2 tons (t) of landed mass, this system can carry four crew members and cargo up to 20 metric t.

The proposed mission architecture for the Mars Molniya Orbit Atmospheric Resource Mining concept incorporates a wide range of vehicle classes. These vehicles will make a robust, affordable and routine round-trip travel between Earth and Mars for cargo and crew, thereby helping to expand human civilization to Mars.

NIAC Mars Atmospheric Gas Resources Collector Vehicle (RCV) stack concept during an aerobraking CO2 collection pass in the upper atmosphere. Credit: NASA

A representative decaying highly elliptic Molniya orbit around Mars.

Credit: (CNBC Life) Space Mining could be a $1 Trillion business according to Chris Lewicki, president of Planetary Resources, a company which hopes to reach asteroids to extract water and mine for metals like platinum. CNBC’s Jane Wells visited Planetary Resources in Seattle, Washington.

Are you ready to mining moon? Because...

«If initiated soon, a lunar depot could be in operation by 2021», say Bigelow Aerospace's President and founder, Robert T. Bigelow.

Credit: Bigelow Aerospace

Imagine a world with ubiquitous, affordable space travel, where getting in a spaceship is no stranger than getting in an airplane. Harvard undergraduate Nina Hooper, an astrophysics student, shows how mining asteroids for platinum could be the way to make space travel cheap and accessible to civilians. Nina Hooper is a Harvard College student from Melbourne, Australia studying astrophysics.

Credit: TEDx Talks

 She loves traveling and adventure and is working towards what she believes is the ultimate adventure - going to space. She is also a private pilot, a songwriter and a major foodie. Nina intends to pursue a graduate degree in aerospace and astrospace engineering either in the US or UK. This talk was given at a TEDx event using the TED conference format but independently organized by a local community.

ISRU Propellant's Application

A Propellant need to meet many criteria to be considered as basis for transportation architecture. First, it must have thermal stability to operate in a liquid rocket engine, means the ability to cool engine throat critical heat flux, avoiding thermal decomposition and coking in engine coolant channels, as well as offers sufficiently high engine specific impulse (Isp).

From a vehicle system, it is the combined characteristic of propellant Isp and bulk density in meeting the vehicle impulsive velocity (DeltaV) mission requirement that offers either the lowest mass or lowest propellant tank volume that warrants the selection. So... 

The cryogenic Liquid Hydrogen(LH2), with its Normal Boiling Point at 36.6 degree Rankin, has an excellent gravimetric heat of combustion (energy per mass) and can generates an High Engine Specific Impulse when combusted with Liquid Oxygen (LO2). Used in launch vehicles for first stage and upper stage applications, it is the fuel of choice for In-Space Propulsion Stage because that high Isp value.

Its disadvantage is that, because it has a low volumetric heat of combustion due to its low density and boiling point, it required techniques for tank insulation and Cryo-Fluid Management to reduce its boil-off. These additional complexity and low dry mass for the stage, reduce its overall usable propellant mass fraction.

Rocket Propellant (RP-1) is a high density kerosene-based fuel commonly used in launch vehicles and, it can be stored in ambient temperature, no tank insulation or tank thermal conditioning is required. Its density is closer to that of LO2, thereby offers total tank volume efficiency. But, because it freezes at -60 degree Fahrenheit (400 degree Rankin), it required thick tank insulation or heaters to avoid the fuel freezing. These latter approach are considered not practical for Space applications.

One big NASA's focus is the Methane (CH4) because it give the advantage of “green” propellant, which minimizes environmental impact with its exhausts. Also, its main advantage is the perceived ease of manufacturing via the ISRU method and provide high density which offer a lower propellant tank volume.

As part of green propellant family, Propane (C3H8) is selected because it offers a good range of low freezing point and relatively high boiling point. Like Methane's ISRU production, it can be manufactured via similar method, be subcooled and thereby, increasing its density and, by the way, reducing its tank volume. 

Another Green propellant, Ethylene (C2H4)is selected because of its relative high Engine Isp and, like Methane and Ethanol, can be further subcooled to reduce tank volume. 

Reference: 49th AIAA/ASME/SAE/ASEE, Joint Propulsion Conference, San Jose, California/AIAA-2013-3804.