ARRM Archives

April 26, 2016April 26, 2016 by Ken Kremer

NASA Selects Aerojet Rocketdyne to Develop Solar Electric Propulsion for Deep Space Missions

This prototype 13-kilowatt Hall thruster was tested at NASA's Glenn Research Center in Cleveland and will be used by industry to develop high-power solar electric propulsion into a flight-qualified system. Credits: NASA

NASA has selected Aerojet Rocketdyne to design and develop an advanced solar electric propulsion (SEP) system that will serve as a critical enabling technology for sending humans and robots on deep space exploration missions to cislunar space, asteroids and the Red Planet.

Under the 3 year, $67 million contract award, Aerojet Rocketdyne will develop the engineering development unit for an Advanced Electric Propulsion System (AEPS) with the potential for follow on flight units.

NASA hopes that the work will result in a 10 fold increase in “spaceflight transportation fuel efficiency compared to current chemical propulsion technology and more than double thrust capability compared to current electric propulsion systems.”

The SEP effort is based in part on NASA’s exploratory work on Hall ion thrusters which trap electrons in a magnetic field and uses them to ionize and accelerate the onboard xenon gas propellant to produce thrust much more efficiently than chemical thrusters.

The solar electric propulsion (SEP) system technology will afford benefits both to America’s commercial space and scientific space exploration capabilities.

For NASA, the SEP technology can be applied for expeditions to deep space such as NASA’s planned Asteroid Robotic Redirect Mission (ARRM) to snatch a boulder from the surface of an asteroid and return it to cislunar space during the 2020s, as well as to carry out the agency’s ambitious plans to send humans on a ‘Journey to Mars’ during the 2030s.

“High power SEP is a perfect example of NASA developing cross cutting technologies to enable both human and robotic deep space missions. Basically it enables high efficiency and better gas mileage,” said Steve Jurczyk, associate administrator of NASA’s Space Technology Mission Directorate (STMD) in Washington, at a media briefing.

“The advantage here is the higher power and the higher thrust.”

“Our plan right now is to flight test the higher power solar electric propulsion that Aerojet Rocketdyne will develop for us on the Asteroid Redirect Robotic Mission (ARRM), which is going to go out to an asteroid with a robotic system, grab a boulder off of an asteroid, and bring it back to a lunar orbit.”

ARRM would launch around 2020 or 2021. Astronauts would blast off several years later in NASA’s Orion crew capsule in 2025 after the robotic probes travels back to lunar orbit.

For industry, electric propulsion is used increasingly to maneuver thrusters in Earth orbiting commercial satellites for station keeping in place of fuel.

“Through this contract, NASA will be developing advanced electric propulsion elements for initial spaceflight applications, which will pave the way for an advanced solar electric propulsion demonstration mission by the end of the decade,” says Jurczyk.

“Development of this technology will advance our future in-space transportation capability for a variety of NASA deep space human and robotic exploration missions, as well as private commercial space missions.”

This 13-kilowatt Hall thruster is being evaluated at NASA’s Glenn Research Center in Cleveland for advanced solar electric propulsion. Hall thrusters trap electrons in a magnetic field and use them to ionize the onboard propellant. Credits: NASA

“This is also a critical capability for enabling human missions to Mars, with respect to delivering cargo to the surface to Mars that will allow people to live and work there on the surface. Also for combined chemical and SEP systems on a spacecraft to propel humans to Mars,” elaborated Jurczyk at the briefing.

“Another application is round trip robotic science missions to Mars to bring back samples – such as a Mars Sample Return (MSR) mission.”

The starting point is NASA’s development and technology readiness testing of a prototype 13-kilowatt Hall thruster and power processing unit at NASA’s Glenn Research Center in Cleveland.

Under the contract award Aerojet Rocketdyne aims to carry out the industrial development of “high-power solar electric propulsion into a flight-qualified system.”

They will develop, build, test and deliver “an integrated electric propulsion system consisting of a thruster, power processing unit (PPU), low-pressure xenon flow controller, and electrical harness,” as an engineering development unit.

This engineering development unit serves as the basis for producing commercial flight units.

If successful, NASA has an option to purchase up to four integrated flight units for actual space missions. Engineers from NASA Glenn and the Jet Propulsion Laboratory (JPL) will provide technical support.

“We could string together four of these engine units to get approximately 50 kilowatts of electrical propulsion capability and with that we can do significant orbital transfer operations. That then becomes the next step in deep space exploration operations that we are trying to do,” said Bryan Smith, director of the Space Flight Systems Directorate at NASA’s Glenn Research Center in Cleveland, at the media briefing.

“We hope to buy four of these units for the ARRM mission.”

What were some of NASA’s research and development (R&D) activities and further plans for Aerojet Rocketdyne?

“NASA is driving out the technology itself for feasibility. So we produced a developmental device to operate at these levels,” Smith told Universe Today during the briefing.

“Other key characteristics we were looking for is the ability to do magnetic shielding. The purpose was to allow for a long life thruster operation. We investigated attributes like thermal problems and balancing the erosion mechanisms in developmental units. So we were looking for things to get longer life and feasibility in developmental units.”

“Once we were comfortable with the feasibility in developmental units, we are now transferring the information, technology and knowhow into what is a production article, in this contract.”

Robotic sampling arm and capture mechanism to collect a multi-ton boulder from an asteroid are under development at NASA Goddard and other agency centers for NASA’s unmanned Asteroid Redirect Vehicle and eventual docking in lunar orbit with Orion crew vehicle by the mid 2020s. Credit: Ken Kremer/kenkremer.com

Solar electric ion propulsion is already being used in NASA’s hugely successful Dawn asteroid orbiter mission.

Dawn was launched in 2007. It orbited and surveyed Vesta in 2011 and 2012 and then traveled outward to Ceres.

Dawn arrived at dwarf planet Ceres in March 2015 and is currently conducting breakthrough science at its lowest planned science mapping orbit.

This image was taken by NASA's Dawn spacecraft of dwarf planet Ceres on Feb. 19 from a distance of nearly 29,000 miles (46,000 km). It shows that the brightest spot on Ceres has a dimmer companion, which apparently lies in the same basin. See below for the wide view. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA — This image was taken by NASA’s Dawn spacecraft of dwarf planet Ceres on Feb. 19 from a distance of nearly 29,000 miles (46,000 km). It shows that the brightest spot on Ceres has a dimmer companion, which apparently lies in the same basin. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

A key part of the Journey to Mars, NASA will be sending cargo missions to the Red Planet to pave the way for human expeditions with the Orion crew module and Space Launch System.

Aerojet Rocketdyne states that “Solar Electric Propulsion (SEP) systems have demonstrated the ability to reduce the mission cost for NASA Human Exploration cargo missions by more than 50 percent through the use of existing flight-proven SEP systems.”

“Using a SEP tug for cargo delivery, combined with NASA’s Space Launch System and the Orion crew module, provides an affordable path for deep space exploration,” said Aerojet Rocketdyne Vice President, Space and Launch Systems, Julie Van Kleeck.

Aerojet Rocketdyne artists concept for solar electric propulsion system for deep space missions. Credit: Aerojet Rocketdyne

Another near term application of high power solar electric propulsion could be for NASA’s proposed Mars 2022 telecom orbiter, said Smith at the media briefing.

Other NASA technology work in progress includes development of more efficient, advanced solar array systems to generate the additional power required for the larger electric thrusters.

Orbital ATK was part of the development effort and already used some of its technology development in the ultraflex solar arrays on the recent Cygnus cargo ships delivering supplies to the ISS.

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer

February 12, 2016February 13, 2016 by Ken Kremer

Obama Administration Proposes Smaller 2017 NASA Budget of $19 Billion with Big Exploration Cuts

NASA releases budget request for Fiscal Year 2017. Credit: NASA

The Obama Administration has announced its new Federal budget and is proposing to cut NASA’s Fiscal Year 2017 Budget to $19 billion by carving away significant funding for deep space exploration, whereas the overall US Federal budget actually increases to over $4.1 trillion.

This 2017 budget request amounts to almost $300 million less than the recently enacted NASA budget for 2016 and specifically stipulates deep funding cuts for deep space exploration programs involving both humans and robots, during President Obama’s final year in office.

The 2017 budget proposal would slash funding to the very programs designed to expand the frontiers of human knowledge and aimed at propelling humans outward to the Red Planet and robots to a Jovian moon that might be conducive to the formation of life.

Absent sufficient and reliable funding to keep NASA’s exploration endeavors on track, further launch delays are almost certainly inevitable – thereby fraying American leadership in space and science.

The administration is specifying big funding cuts to the ongoing development of NASA’s mammoth Space Launch System (SLS) heavy lift rocket and the state of the art Orion deep space crew capsule. They are the essential first ingredients to carry out NASA’s ambitious plans to send astronauts on deep space ‘Journey to Mars’ expeditions during the 2030s.

The overall Exploration Systems Development account for human deep space missions would be slashed about 18 percent from the 2016 funding level; from $4.0 Billion to only $3.3 Billion, or nearly $700 million.

SLS alone is reduced the most by $700 million from $2.0 billion to $1,31 billion, or a whopping 35 percent loss. Orion is reduced from $1.27 billion to $1.12 billion for a loss of some $150 million.

Make no mistake. These programs are already starved for funding and the Obama administration tried to force similar cuts to these programs in 2016, until Congress intervened.

Likewise, the Obama administration is proposing a draconian cut to the proposed robotic mission to Jupiter’s moon Europa that would surely delay the launch by at least another half a decade or more – to the late 2020s.

The Europa mission budget proposal is cut to only $49 million and the launch is postponed until the late 2020s. The mission received $175 million in funding in 2016 – amounting to a 72 percent reduction.

Furthermore there is no funding for a proposed lander and the launch vehicle changes from SLS to a far less powerful EELV – causing a year’s long increased travel time.

In order to maintain an SLS launch in approximately 2022, NASA would require a budget of about $150 million in 2017, said David Radzanowski, NASA’s chief financial officer, during a Feb. 9 teleconference with reporters.

Why is Europa worth exploring? Because Europa likely possesses a subsurface ocean of water and is a prime target in the search for life!

Overall, NASA’s hugely successful Planetary Sciences division suffers a huge and nearly 10 percent cut of $141 million to $1.51 billion – despite undeniably groundbreaking scientific successes this past year at Pluto, Ceres, Mars and more!

Altogether NASA would receive $19.025 billion in FY 2017. This totals $260 million less than the $19.285 billion appropriated in FY 2016, and thus corresponds to a reduction of 1.5 percent.

By contrast, the overall US Federal Budget will increase nearly 5 percent to approximately $4.1 trillion. Simple math demonstrates that NASA is clearly not a high priority for the administration. NASA’s share of the Federal budget comes in at less than half a cent on the dollar.

Orion crew module pressure vessel for NASA’s Exploration Mission-1 (EM-1) is unveiled for the first time on Feb. 3, 2016 after arrival at the agency’s Kennedy Space Center (KSC) in Florida. It is secured for processing in a test stand called the birdcage in the high bay inside the Neil Armstrong Operations and Checkout (O&C) Building at KSC. Launch to the Moon is slated in 2018 atop the SLS rocket. Credit: Ken Kremer/kenkremer.com

NASA’s Fiscal Year 2017 budget proposal was announced by NASA Administrator Charles Bolden during a televised ‘State of NASA’ address at the agency’s Langley Research Center in Virginia on Feb. 9.

Bolden did not dwell at all on the significant funding reductions for exploration.

“We are hitting our benchmarks with new exploration systems like the Space Launch System rocket and the Orion Crew Vehicle. A new consensus is emerging in the scientific and policy communities around our vision, timetable and plan for sending American astronauts to Mars in the 2030s.”

And he outlined some milestones ahead.

“We’ll continue to make great progress on the Space Launch System – SLS–rocket and we’re preparing for a second series of engine tests,” said Bolden.

“At the Kennedy Space Center, our teams will outfit Orion’s crew module with the spacecraft’s heat-shielding thermal protection systems, avionics and subsystems like electrical power storage, cabin pressure control and flight software –to name just a few.”

NASA’s Space Launch System (SLS) blasts off from launch pad 39B at the Kennedy Space Center in this artist rendering showing a view of the liftoff of the Block 1 70-metric-ton (77-ton) crew vehicle configuration. Credit: NASA/MSFC

NASA plans to launch the first combined SLS/Orion on the uncrewed Exploration Mission-1 (EM-1) in November 2018.

Indeed the Orion EM-1 pressure vessel just arrived at the Kennedy Space Center last week to completely install all the systems required for flight.

NASA’s Orion EM-1 crew module pressure vessel arrived at the Kennedy Space Center’s Shuttle Landing Facility tucked inside NASA’s Super Guppy aircraft on Feb 1, 2016. The Super Guppy opens its hinged nose to unload cargo. Credit: Ken Kremer/kenkremer.com

The launch date for the first crewed flight on EM-2 was targeted for 2021. But EM-2 is likely to slip to the right to 2023, due to insufficient funding.

Lack of funding will also force NASA to delay development of the far more capable and powerful Exploration Upper Stage (EUS) to propel Orion on deep space missions. It will now not be available for the SLS/EM-2 launch as hoped.

The proposed huge budget cuts to SLS, Orion and Europa are certain to arose the ire of multiple members of Congress and space interest groups, who just successfully fought to increase NASA’s FY 2016 budget for these same programs in the recently passed 2016 omnibus spending bill.

“This administration cannot continue to tout plans to send astronauts to Mars while strangling the programs that will take us there,” said Rep. Lamar Smith (R-Texas), Chairman of the House Science, Space, and Technology Committee, in a statement in response to the president’s budget proposal.

“President Obama’s FY17 budget proposal shrinks our deep space exploration programs by more than $800 million. And the administration once more proposes cuts of more than $100 million to the Planetary Science accounts, which have previously funded missions like this past year’s Pluto flyby.”

“This imbalanced proposal continues to tie our astronauts’ feet to the ground and makes a Mars mission all but impossible. This is not the proposal of an administration that is serious about maintaining America’s leadership in space.”

A "true color" image of the surface of Jupiter's moon Europa as seen by the Galileo spacecraft. Image credit: NASA/JPL-Caltech/SETI Institute — A “true color” image of the surface of Jupiter’s moon Europa as seen by the Galileo spacecraft. Image credit: NASA/JPL-Caltech/SETI Institute

“The Coalition for Deep Space Exploration … had hoped the request would reflect the priorities laid out for NASA in the FY16 Omnibus, for which there was broad support,” said Mary Lynne Dittmar, executive director of the Coalition for Deep Space Exploration, in a statement.

“Unfortunately this was not the case. The Coalition is disappointed with the proposed reduction in funding below the FY16 Omnibus for NASA’s exploration programs. We are deeply concerned about the Administration’s proposed cut to NASA’s human exploration development programs.”

“This proposed budget falls well short of the investment needed to support NASA’s exploration missions, and would have detrimental impacts on cornerstone, game-changing programs such as the super-heavy lift rocket, the Space Launch System (SLS), and the Orion spacecraft – the first spacecraft designed to reach multiple destinations in the human exploration of deep space.”

Homecoming view of NASA’s first Orion spacecraft after returning to NASA’s Kennedy Space Center in Florida on Dec. 19, 2014 after successful blastoff on Dec. 5, 2014. Credit: Ken Kremer - kenkremer.com — Homecoming view of NASA’s first Orion spacecraft after returning to NASA’s Kennedy Space Center in Florida on Dec. 19, 2014 after successful blastoff on Dec. 5, 2014. Credit: Ken Kremer – kenkremer.com

Funding for the James Webb Space Telescope (JWST) was maintained at planned levels to keep it on track for launch in 2018.

All 18 primary mirrors of NASA’s James Webb Space Telescope are seen fully installed on the backplane structure by technicians using a robotic arm (center) inside the massive clean room at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Credit: Ken Kremer/kenkremer.com — All 18 primary mirrors of NASA’s James Webb Space Telescope are seen fully installed on the backplane structure by technicians using a robotic arm (center) inside the massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Credit: Ken Kremer/kenkremer.com

On Dec. 18, 2015, the US Congress passed and the president signed the 2016 omnibus spending bill which funds the US government through the remainder of the 2016 Fiscal Year.

As part of the omnibus bill, NASA’s approved budget amounted to nearly $19.3 Billion. That was an outstanding result and a remarkable turnaround to some long awaited good news from the decidedly negative outlook earlier in 2015.

The 2016 budget represented an increase of some $750 million above the Obama Administration’s proposed NASA budget allocation of $18.5 Billion for Fiscal Year 2016, and an increase of more than $1.2 Billion over the enacted budget for FY 2015.

Under the proposed NASA budget for Fiscal Year 2017, the fictional exploits of ‘The Martian’ will never become reality.

And the hunt for extraterrestrial life on the icy moons of the outer solar system is postponed yet again.

Scene from ‘The Martian’ starring Matt Damon as NASA astronaut Mark Watney contemplating magnificent panoramic vista while stranded alone on Mars. Credits: 20th Century Fox

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

This global mosaic view of Pluto was created from the latest high-resolution images to be downlinked from NASA’s New Horizons spacecraft and released on Sept. 11, 2015. The images were taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). This mosaic was stitched from over two dozen raw images captured by the LORRI imager and colorized. Right side mosaic comprises twelve highest resolution views of Tombaugh Regio heart shaped feature and shows objects as small as 0.5 miles (0.8 kilometers) in size. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/ Ken Kremer/kenkremer.com/Marco Di Lorenzo

October 27, 2015December 23, 2015 by Ken Kremer

Boulder Extraction and Robotic Arm Mechanisms For NASA’s Asteroid Redirect Mission Start Rigorous Testing at NASA Goddard

NASA GODDARD SPACE FLIGHT CENTER, MD – Rigorous testing has begun on the advanced robotic arm and boulder extraction mechanisms that are key components of the unmanned probe at the heart of NASA’s Asteroid Redirect Robotic Mission (ARRM) now under development to pluck a multi-ton boulder off a near-Earth asteroid so that astronauts visiting later in an Orion crew capsule can harvest a large quantity of samples for high powered scientific analysis back on Earth. Universe Today inspected the robotic arm hardware utilizing “leveraged robotic technology” during an up close visit and exclusive interview with the engineering development team at NASA Goddard.

“The teams are making great progress on the capture mechanism that has been delivered to the robotics team at Goddard from Langley,” NASA Associate Administrator Robert Lightfoot told Universe Today.

“NASA is developing these common technologies for a suite of missions like satellite servicing and refueling in low Earth orbit as well as autonomously capturing an asteroid about 100 million miles away,” said Ben Reed, NASA Satellite Servicing Capabilities Office (SSCO) Deputy Project Manager, during an exclusive interview and hardware tour with Universe Today at NASA Goddard in Greenbelt, Maryland, regarding concepts and goals for the overall Asteroid Redirect Mission (ARM) initiative.

NASA is leveraging technology originally developed for satellite servicing such as with the Robotic Refueling Mission (RRM) currently on board the International Space Station (ISS) and repurposing them for the asteroid retrieval mission.

“Those are our two near term mission objectives that we are developing these technologies for,” Reed explained.

ARRM combines both robotic and human missions to advance the new technologies required for NASA’s agency wide ‘Journey to Mars’ objective of sending a human mission to the Martian system in the 2030s.

The unmanned Asteroid Redirect Robotic Mission (ARRM) to grab a boulder is the essential first step towards carrying out the follow on sample retrieval with the manned Orion Asteroid Redirect Mission (ARM) by the mid-2020s.

ARRM will use a pair of highly capable robotic arms to autonomously grapple a multi-ton (> 20 ton) boulder off the surface of a large near-Earth asteroid and transport it to a stable, astronaut accessible orbit around the Moon in cislunar space.

“Things are moving well. The teams have made really tremendous progress on the robotic arm and capture mechanism,” Bill Gerstenmaier, NASA Associate Administrator for Human Exploration and Operations, told Universe Today.

Then an Orion crew capsule can fly to it and the astronauts will collect a large quantity of rock samples and gather additional scientific measurements.

“We are working on a system to rendezvous, capture and service different [target] clients using the same technologies. That is what we are working on in a nut shell,” Reed said.

This engineering design unit of the robotic servicing arm is under development to autonomously extract a boulder off an asteroid for NASA’s asteroid retrieval mission and is being tested at NASA Goddard. It has seven degrees of freedom and mimics a human arm. Credit: Ken Kremer/kenkremer.com

“Right now the plan is to launch ARRM by about December 2020,” Reed told me. But a huge amount of preparatory work across the US is required to turn NASA’s plan into reality.

Key mission enabling technologies are being tested right now with a new full scale engineering model of the ‘Robotic Servicing Arm’ and a full scale mockup of the boulder snatching ARRM Capture Module at NASA Goddard, in a new facility known as “The Cauldron.”

Capture Module comprising two robotic servicing arms and three boulder grappling contact and restraint system legs for NASA’s Asteroid Redirect Robotic Mission (ARRM). Credit: NASA

The ARRM capture module is comprised of two shorter robotic arms (separated by 180 degrees) and three lengthy contact and restraint system capture legs (separated by 120 degrees) attached to a cradle with associated avionics, computers and electronics and the rest of the spacecraft and solar electric power arrays.

“The robotic arm we have here now is an engineering development unit. The 2.2 meter-long arms can be used for assembling large telescopes, repairing a failed satellite, removing orbital debris and capturing an asteroid,” said Reed.

“There are two little arms and three big capture legs.”

“So, we are leveraging one technology development program into multiple NASA objectives.”

“We are working on common technologies that can service a legacy orbiting satellite, not designed to be serviced, and use those same technologies with some tweaking that we can go out with 100 million miles and capture an asteroid and bring it back to the vicinity of the Moon.”

“Currently the [capture module] system can handle a boulder that’s up to about 3 x 4 x 5 meters in diameter.”

Artists concept of NASA’s Asteroid Redirect Robotic Mission capturing an asteroid boulder before redirecting it to a astronaut-accessible orbit around Earth's moon. Credits: NASA — Artists concept of NASA’s Asteroid Redirect Robotic Mission capturing an asteroid boulder before redirecting it to a astronaut-accessible orbit around Earth’s moon. Credits: NASA

The Cauldron is a brand new Goddard facility for testing technologies and operations for multiple exploration and science missions, including satellite servicing and ARRM that just opened in June 2015 for the centers Satellite Servicing Capabilities Office.

Overall project lead for ARRM is the Jet Propulsion Laboratory (JPL) with numerous contributions from other NASA centers and industrial partners.

“This is an immersive development lab where we bring systems together and can do lifetime testing to simulate what’s in space. This is our robotic equivalent to the astronauts NBL, or neutral buoyancy lab,” Reed elaborated.

“So with this same robotic arm that can cut wires and thermal blankets and refuel an Earth sensing satellite, we can now have that same arm go out on a different mission and be able to travel out and pick up a multi-ton boulder and bring it back for astronauts to harvest samples from.”

“So that’s quite a technical feat!”

The Robotic Servicing Arm is a multi-jointed powerhouse designed to function like a “human arm” as much as possible. It builds on extensive prior research and development investment efforts conducted for NASA’s current Red Planet rovers and a flight-qualified robotic arm developed for the Defense Advanced Research Projects Agency (DARPA).

“The arm is capable of seven-degrees-of-freedom to mimic the full functionally of a human arm. It has heritage from the arm on Mars right now on Curiosity as well as ground based programs from DARPA,” Reed told me.

“It has three degrees of freedom at our shoulder, two at our elbow and two more at the wrist. So I can hold the hand still and move the elbow.”

The arm will also be equipped with a variety of interchangeable “hands” that are basically tools to carry out different tasks with the asteroid such as grappling, drilling, sample gathering, imaging and spectrometric analysis, etc.

View of the robotic arm above and gripper tool below that initially grabs the asteroid boulder before the capture legs wrap around as planned for NASA’s upcoming unmanned ARRM Asteroid Redirect Robotic Mission that will later dock with an Orion crew vehicle. Credit: Ken Kremer/kenkremer.com

The ARRM spacecraft will carefully study, characterize and photograph the asteroid in great detail for about a month before attempting the boulder capture.

Why does the arm need all this human-like capability?

“When we arrive at an asteroid that’s 100 million miles away, we are not going to know the fine local geometry until we arrive,” Reed explained to Universe Today.

“Therefore we need a flexible enough arm that can accommodate local geometries at the multi-foot scale. And then a gripper tool that can handle those geometry facets at a much smaller scale.”

“Therefore we chose seven-degrees-of-freedom to mimic humans very much by design. We also need seven-degrees-of-freedom to conduct collision avoidance maneuvers. You can’t do that with a six-degree-of-freedom arm. It has to be seven to be a general purpose arm.”

How will the ARRM capture module work to snatch the boulder off the asteroid?

“So the idea is you come to the mother asteroid and touch down and make contact on the surface. Then you hold that position and the two arms reach out and grab the boulder.”

“Once its grabbed the boulder, then the legs straighten and pull the boulder off the surface.”

“Then the arms nestle the asteroid onto a cradle. And the legs then change from a contact system to become a restraint system. So the legs wrap around the boulder to restrain it for the 100 million mile journey back home.

“After that the little arms can let go – because the legs have wrapped around and are holding the asteroid.”

“So now the arm can also let go of the gripper system and pick up a different tool to do other things. For example they can collect a sample with another tool. And maybe assist an astronaut after the crew arrives.”

“During the 100 million mile journey back to lunar orbit they can be also be preparing the surface and cutting into it for later sample collection by the astronauts.”

Be sure to watch this video animation:

Since the actual asteroid encounter will occur very far away, the boulder grappling will have to be done fully autonomously since there will be no possibility for real time communications.

“The return time for communications is like about 30 minutes. So ‘human in the loop’ control is out of the question.

“Once we get into hover position over the landing site we hit the GO button. Then it will be very much like at Mars and the seven minutes of terror. It will take awhile to find out if it worked.”

Therefore the team at Goddard has already spent years of effort and practice sessions just to get ready for working with the early engineering version of the arm to maximize the probability of a successful capture.

“In this facility we put systems together to try and practice and rehearse and simulate as much of the mission as is realistically possible.”

“It took a lot of effort to get to this point, in the neighborhood of four years to get the simulation to behave correctly in real time with contact dynamics and the robotic systems. So the arm has to touch the boulder with force torque sensors and feed that into a computer to measure that and move the actuators to respond accordingly.”

“So the capture of the boulder is autonomous. The rest is teleoperated from the ground, but not the capture itself.”

How realistic are the rehearsals?

“We are practicing here by reaching out with the arm to grasp the client target using autonomous capture [procedures]. In space the client [target] is floating and maybe tumbling. So when we reach out with the arm to practice autonomous capture we make the client tumble and move – with the inertial properties of the target we are practicing on.”

“Now for known objects like satellites we know the mass precisely. And we can program all that inertial property data in very accurately to give us much more realistic simulations.”

“We learned from all our astronaut servicing experiences in orbit is that the more we know for the simulations, the easier and better the results are for the astronauts during an actual mission because you simulated all the properties.”

“But with this robotic mission to an asteroid there is no backup like astronauts. So we want to practice here at Goddard and simulate the space environment.”

ARRM will launch by the end of 2020 on either an SLS, Delta IV Heavy or a Falcon Heavy. NASA has not yet chosen the launch vehicle.

Several candidate asteroids have already been discovered and NASA has an extensive ongoing program to find more.

Orion crew capsule docks to NASA’s asteroid redirect vehicle grappling captured asteroid boulder orbiting the Moon. Credit: NASA

Again, this robotic technology was selected for development for ARRM because it has a lot in common with other objectives like fixing communications satellites, refueling satellites and building large telescopes in the future.

NASA is also developing other critical enabling technologies for the entire ARM project like solar electric propulsion that will be the subject of another article.

Therefore NASA is leveraging one technology development program into multiple spaceflight objectives that will greatly assist its plans to send ‘Humans to Mars’ in the 2030s with the Orion crew module launched by the monster Space Launch System (SLS) rocket.

The maiden uncrewed launch of the Orion/SLS stack is slated for November 2018.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer