MIT team proposes storing extra rocket fuel in space for future missions

By Jennifer Chu, MIT News Office

Future lunar missions may be fueled by gas stations in space, according to MIT engineers: A spacecraft might dock at a propellant depot, somewhere between the Earth and the Moon, and pick up extra rocket fuel before making its way to the lunar surface.

Orbiting way stations could reduce the fuel a spacecraft needs to carry from Earth — and with less fuel onboard, a rocket could launch heavier payloads, such as large scientific experiments.

Over the last few decades, scientists have proposed various designs, such as building a fuel-manufacturing station on the Moon and sending tankers to refill floating depots. But most ideas have come with hefty price tags, requiring long-term investment.

The MIT team has come up with two cost-efficient depot designs that do not require such long-term commitment. Both designs take advantage of the fact that each lunar mission carries a supply of “contingency propellant” — fuel that’s meant to be used only in emergencies. In most cases, this backup fuel goes unused, and is either left on the Moon or burned up as the crew re-enters the Earth’s atmosphere.

Instead, the MIT team proposes using contingency propellant from past missions to fuel future spacecraft. For instance, as a mission heads back to Earth, it may drop a tank of contingency propellant at a depot before heading home. The next mission can pick up the fuel tank on its way to the Moon as its own emergency supply. If it ends up not needing the extra propellant, it can also drop it at the depot for the next mission — an arrangement that the team refers to as a “steady-state” approach.

A depot may also accumulate contingency propellant from multiple missions, part of an approach the researchers call “stockpiling.” Spacecraft heading to the Moon would carry contingency propellant as they normally would, dropping the tank at a depot on the way back to Earth if it’s not needed; over time, the depot builds up a large fuel supply. This way, if a large lunar mission launches in the future, its rocket wouldn’t need a huge fuel supply to launch the heavier payload. Instead, it can stop at the depot to collect the stockpiled propellant to fuel its landing on the Moon.

“Whatever rockets you use, you’d like to take full advantage of your lifting capacity,” says Jeffrey Hoffman, a professor of the practice in MIT’s Department of Aeronautics and Astronautics. “Most of what we launch from the Earth is propellant. So whatever you can save, there’s that much more payload you can take with you.”

Hoffman and his students — Koki Ho, Katherine Gerhard, Austin Nicholas, and Alexander Buck — outline their depot architecture in the journal Acta Astronautica.

Pickup and drop-off in space

The researchers came up with a basic mission strategy to return humans to the Moon, one slightly different from that of the Apollo missions. During the Apollo era, spacecraft circled close to the lunar equator — a route that required little change in direction, and little fuel to stay on track. In the future, lunar missions may take a more flexible approach, with the freedom to change course to explore farther reaches of the Moon — such as the polar caps, for evidence of water — a strategy that would require each spacecraft to carry extra fuel to change orbits.

Working under the assumption of a more global exploration strategy, the researchers designed a basic architecture involving a series of stand-alone missions, each exploring the surface of the Moon for seven to 14 days. This mission plan requires that a spacecraft returning to Earth must change its orbital plane when needed. Under this basic scenario, missions could operate under existing infrastructure, without fuel depots, meaning that each spacecraft would carry its own supply of contingency propellant.

The researchers then drew up two depot designs to improve the efficiency of the basic scenario. In both designs, depots would be stationed at Lagrange points — regions in space between the Earth, Moon, and sun that maintain gravitational equilibrium. Objects at these points remain in place, keeping the same relative position with respect to the Earth and the Moon.

Hoffman says that ideally, transferring fuel between the depot and a spacecraft would simply involve astronauts or a robotic arm picking up a tank. The alternative — siphoning fuel from tank to tank like you would for your car — is a bit trickier, as liquid tends to float in a gravity-free environment. But, Hoffman says, it’s doable.

“In building the International Space Station, every time a new module is added, we’ve had to hook up new fluid connections,” Hoffman says. “It’s not a trivial design problem, but it can be done.”

‘Creating value … against political uncertainty’

The main drawbacks for both depot designs include maintenance; keeping depots within the Lagrange point; and preventing a phenomenon, called “boil-off,” in which fuel that’s not kept at cold-enough temperatures can boil away. If scientists can find ways around these challenges, Hoffman says, gas stations in space could be an efficient way to support large lunar explorations.

“One of the problems with large space programs is, you invest a huge amount in building up the infrastructure, and then a program gets canceled,” Hoffman says. “With depot architectures, you’re creating value which is robust against political uncertainty.”

The paper came out of two MIT classes taught by Hoffman: 16.851 (Satellite Engineering) and 16.89 (Space Systems Engineering), in which students also looked at redesigning a lunar lander and evaluated different approaches to landing on the Moon.

James Head, a professor of geological sciences at Brown University, says the group’s two approaches optimize the possibility of both near-lunar missions and more ambitious, longer-duration missions to more distant destinations.

“Currently, NASA is once again considering circumlunar human operations and developing architectures for moving on to Mars,” Head says. “So this paper is extremely important and timely in the context of developing NASA plans for human exploration beyond low Earth orbit.”

See also on the NSS website: Orbital Propellant Depots: Building the Interplanetary Highway.

National Space Society Supports 2015 NASA Commercial Crew Budget

The Washington DC-based National Space Society (NSS) has been a consistent supporter of NASA’s Commercial Crew program to ferry astronauts to the International Space Station (ISS).  In the NSS position paper on the NASA Commercial Crew Program released today, the Society strongly endorses $848 million in the 2015 NASA budget for Commercial Crew, along with the $250 million supplemental Commercial Crew request.  Furthermore, the $171 million “hold” placed on the program last year should be removed.

At a time when the availability of the Russian supplied Soyuz, our current sole method of getting American astronauts to the ISS (at $70 million per seat), is being increasingly questioned and political relations with Russia are deteriorating, we need to move Commercial Crew to the top of NASA’s priority list.

NSS believes, however, that the nature of the Commercial Crew program is as important as the amount of funding.   Commercial Crew must support a minimum of two independent American providers of crewed access to ISS.   Failure to provide this level of capability will lead to rising costs and hinder the growth of a vigorous private commercial launch industry that will lead to a vibrant, sustainable commercial space industry and the high tech jobs growth that it will create.  In addition, NSS believes the Commercial Crew program will have adequate safety, and should proceed without further funding shortfall-based delays.

NSS also endorses the recent decision by the Obama administration to extend the life of the ISS by four years to 2024.  NASA should take additional steps to further extend both the life and the capabilities of the ISS, including using the Commercial Crew vehicles to support a larger ISS crew, creating greater science, technology and commercial output.

NSS Executive Vice President Paul Werbos summed up the situation.  “We face great uncertainty in our ability to access the ISS.  We can develop a competitive, commercially successful American means to do this.  There is little or no benefit to waiting.  Let’s do it.”

See NSS Position Paper on the NASA Commercial Crew Program.

Commercial Crew Program

First Falcon Heavy Launch Delayed Until Next Year

Aviation Week reports:

Although it was initially slated to debut this year, SpaceX founder, CEO and Chief Designer Elon Musk says the company’s production schedule is too tight to support a test flight of the heavy-lift rocket from Vandenberg AFB, Calif., in 2014.

“We need to find three additional cores that we could produce, send them through testing and then fly without disrupting our launch manifest,” Musk said in a Feb. 20 interview. “I’m hopeful we’ll have Falcon Heavy cores produced approximately around the end of the year. But just to get through test and qualification, I think it’s probably going to be sometime early next year when we launch.”

Mercury MESSENGER Team Wins National Space Society’s Space Pioneer Award for Science and Engineering

The National Space Society takes great pleasure in awarding its 2014 Space Pioneer Award for the Science and Engineering category to the (Mercury) MESSENGER Team.  MESSENGER stands for MErcury Surface, Space ENvironment, GEochemistry, and Ranging.  This spacecraft entered an orbit around the planet Mercury and conducted an extensive scientific survey of the entire planet, the first human object to do so.  With this award, NSS recognizes both the importance of the first dedicated probe to orbit Mercury and the significance of the scientific results already released.

The National Space Society will present the Space Pioneer Award to MESSENGER project representatives Drs. Sean C. Solomon, Larry R. Nittler and Ralph McNutt at NSS’s annual conference, the 2014 International Space Development Conference (ISDC).  The conference will be held at the Sheraton Gateway Hotel in Los Angeles, CA.  The ISDC will run from May 14-18, 2014.

About the MESSENGER Team:

The Principal Investigator for the Messenger Team is Dr. Sean C. Solomon. He also directs the prestigious Lamont-Doherty Earth Observatory at Columbia University.  Dr. Larry R. Nittler is MESSENGER’s Deputy Principal Investigator. Dr. Ralph McNutt is MESSENGER’s Project Scientist. The historic achievements of the MESSENGER Team (after construction and launch of the spacecraft) include successfully placing the spacecraft accurately into its intended orbit around Mercury on March 18, 2011, after a series of six critical flybys of the Earth, Venus, and Mercury itself.  Besides the critical contribution of accurately mapping Mercury’s surface, the science results have confirmed the presence of water ice and organic chemicals at the poles, and the fact that Mercury’s magnetic field is offset to the north substantially from its equator.

About the MESSENGER Mission:

MESSENGER confirmed suspicions of major regional volcanism and mapped global patterns of thrust fault scarps that show Mercury has contracted several times more than Mariner 10 data indicated.  Global elemental and mineralogical mapping confirmed Mercury has a low-iron crustal mineralogy, but unexpectedly showed sulfur, potassium and other volatile elements are abundant, upsetting high temperature models of Mercury’s formation.  MESSENGER has discovered pitted “hollows” with bright halos, found in many craters, which appear to involve volatile loss but their formation mechanism remains enigmatic.

About the Space Pioneer Award

Space Pioneer AwardThe Space Pioneer Award consists of a silvery pewter Moon globe cast by the Baker Art Foundry in Placerville, California, from a sculpture originally created by Don Davis, the well-known space and astronomical artist.  The globe, as shown at right, which represents multiple space mission destinations and goals, sits freely on a brass support with a wooden base and brass plaque, which are created by Michael Hall’s Studio Foundry of Driftwood, TX. There are several different categories under which the award is presented each year, starting in 1988.  The NSS Awards Committee has been chaired by John Strickland since 2007 and its members seek prestigious award candidates on a continual basis.

About the ISDC:  The International Space Development Conference (ISDC) is the annual conference of the National Space Society bringing together NSS leaders and members with leading managers, engineers, scientists, educators, and businessmen from civilian, military, commercial, entrepreneurial, and grassroots advocacy space sectors.

New Book: The Case for Space Solar Power

A strong case for harnessing space solar power is presented in this ground-breaking new book. Author John C. Mankins, one of the foremost experts in the field, presents his latest research in The Case for Space Solar Power.

The Case for Space Solar Power

The Case for Space Solar Power recounts the history of the space solar power concept and summarizes the many different ways in which it might be accomplished.

Specifically, the book describes in detail a highly promising concept — SPS-ALPHA (Solar Power Satellite by means of Arbitrarily Large Phased Array) — and presents a business case comprising applications in space and markets on Earth. It is possible to begin now with technologies that are already at hand , while developing the more advanced technologies that will be needed to deliver power economically to markets on Earth.

The Case for Space Solar Power lays out a path forward that is both achievable and affordable. Within a dozen years, the first multi-megawatt solar pilot plant could be in operation.

Given that space solar power can transform our future in space, and provide a new source of virtually limitless and sustainable energy to markets across the world, the book poses the question, “Why wouldn’t we pursue space solar power?”

The book is now available both in hardcopy and in an inexpensive Kindle format at If you don’t have a Kindle, there are free Kindle reader apps at that enable you to read it on your computer, tablet, or other mobile device.

Elon Musk Wins National Space Society Robert A. Heinlein Award

The National Space Society takes great pleasure in announcing that its 2014 Robert A. Heinlein Memorial Award has been won by acclaimed space entrepreneur Elon Musk, the Chief Designer and CEO of SpaceX. In the last decade, SpaceX, under the leadership of Elon Musk, has been moving directly toward accomplishing goals that many of us in NSS think are of utmost importance, such as forcing a drastic reduction in launch costs by doing the very hard task which no one else in the world has been willing and able to tackle: working to create a family of commercially successful and reusable rocket boosters and reusable spacecraft.

The National Space Society’s prestigious Robert A. Heinlein Memorial Award will be presented to Elon Musk at the 2014 International Space Development Conference (ISDC).  The conference will be held at the Sheraton Gateway Hotel in Los Angeles, CA. The ISDC will run from May 14-18, 2014.

The imaginations of our visionaries of the last 100 years will not be fulfilled until affordable, large scale and high mass operations can take place in Earth orbit and beyond. SpaceX’s Dragon spacecraft is reusable and SpaceX is making great progress towards a reusable rocket, the key development that would make such operations possible.

About Elon Musk:

Elon MuskElon Musk was born in South Africa in 1971 and emigrated first to Canada and then to the US.  He has two B.A. degrees, one in physics and one in economics, from the University of Pennsylvania.  He became a multimillionaire in his late twenties when he sold his start-up company, Zip2, to a division of Compaq Computers.  He went on to more early successes, launching PayPal via a 2000 merger.  He founded Space Exploration Technologies Corporation (SpaceX) in 2002, the same year that he became an American citizen and also the same year he earned the money to fund the new company from the sale of PayPal.  The SpaceX Falcon 1 was the first privately funded liquid fueled rocket to put a payload into orbit.  The larger Falcon 9 rocket has been flying since June 2010 and SpaceX is also developing a reusable version called Falcon 9R and a much larger rocket, Falcon Heavy.  SpaceX has a 1.6-billion dollar contract with NASA to supply the space station via its recoverable Dragon spacecraft.  They are also a competitor in NASA’s Commercial Crew Program.

Like NSS, Musk views space exploration as important for the preservation and expansion of humankind. Musk likes to say that we should become “multi-planetary” as a hedge against all threats to our survival. He said, “Sooner or later, we must expand life beyond this green and blue ball—or go extinct.” To help make that happen, Musk’s goal is to reduce the cost of human spaceflight by a factor of 100.

About the Robert A. Heinlein Award

The Heinlein award is presented once every two years for lifetime achievement in promoting the goal of a free, spacefaring civilization. The winner is determined by a vote of the NSS membership. The award consists of a miniature signal cannon, on a mahogany base with a black granite inlay and a brass plaque as shown.  The award concept came from Robert Heinlein’s classic book The Moon is a Harsh Mistress.  Previous winners include Sir Arthur C. Clarke and Dr. Carl Sagan. More information about this award is at:

Heinlein Award

About the ISDC: 

The International Space Development Conference (ISDC) is the annual conference of the National Space Society, bringing together NSS leaders and members with leading managers, engineers, scientists, educators, and businessmen from civilian, military, commercial, entrepreneurial, and grassroots advocacy space sectors.

National Space Society Issues Position Paper on Protecting Earth from Cosmic Impacts

On February 15, 2013, a meteor exploded over the Chelyabinsk region of Russia. The blast damaged over 7,000 buildings and almost 1,500 people suffered injuries requiring treatment. As we observe the anniversary of that event, it is important to understand its significance and specifically what it means for the United States. Millions of objects in space, including asteroids and comets, are in orbits around the Sun that cross Earth’s orbit. When they approach Earth, they are referred to as Near-Earth Objects (NEOs). Some NEOs are large enough to cause significant damage if they impact the Earth. Many such objects have struck Earth in the past, inflicting damage ranging from trivial up to and including global catastrophe. While a future large strike with catastrophic consequences is certain, we do not know whether it will happen in 150 million years or fifteen months.

The Washington DC-based National Space Society (NSS) has been a consistent supporter of actions to defend our home planet from such events. In a position paper released today, the Society focuses attention on the near-term need and the opportunity to significantly improve our ability to detect and track collision threats to the Earth. While recognizing that this is a global problem, the paper focuses on recommended actions for the United States. Additionally, NSS urges all space faring nations to add an amount of at least one percent of their civilian space budget for developing defenses against these threats.

NSS believes that the immediate task before us is to find and track NEOs large enough to cause damage on Earth. To this end, current US ground-based searches should continue, including use of the Arecibo radio telescope. The Large Synoptic Survey Telescope should be fully funded and encouraged to vigorously pursue NEO detection. The B612 Foundation’s Sentinel Project and the JPL NEOCam infra-red space telescope should be fully funded. The Society also feels that now is the time to more seriously address the detection of long period comets. Additional work should be done on NEO characterization and deflection research.

NSS Director and Space Settlement Advocacy Committee chair Al Globus summed up the situation: “We face an existential threat. We can develop the ability to remove it. There is little or no benefit to waiting. Let’s do it.”

See NSS Position Paper on Protecting Earth from Cosmic Impacts.

Elon Musk’s Plans for Mars

From CBS This Morning: 2-minute video after 30-second advertisement.

Transcript after about 40 seconds:

“We’ve got to restore American ability to transport astronauts with domestic vehicles, and that’s what we hope to do in about two years.

“The next step beyond that is to maybe send people beyond low Earth orbit to a loop around the Moon, possibly land on the Moon — although I’m not super interested in the Moon personally because obviously we’ve done that and we know we can — but maybe just to prove the capability.

“Then we need to develop a much larger vehicle which would be sort of what I call a large colonial transport system. This would really be — we’re talking about rockets on a scale, a bigger scale than has ever been done before, that make the Apollo Moon rocket look small. And they would have to launch very frequently as well.

“That’s what’s needed in order to send millions of people and millions of tons of cargo to Mars, which is the minimum level to have a self-sustaining civilization on Mars.

“We might be able to complete that [rocket] in about 10 or 12 years, and hopefully the first people we’d send to Mars would be around the middle of the next decade.”

Water Detected on Largest Object in the Asteroid Belt, Ceres

Scientists using the Herschel space observatory have made the first definitive detection of water vapor on the largest and roundest object in the asteroid belt, Ceres.

Plumes of water vapor are thought to shoot up periodically from Ceres when portions of its icy surface warm slightly. Ceres is classified as a dwarf planet, a solar system body bigger than an asteroid and smaller than a planet.

Herschel is a European Space Agency (ESA) mission with important NASA contributions.

“This is the first time water vapor has been unequivocally detected on Ceres or any other object in the asteroid belt and provides proof that Ceres has an icy surface and an atmosphere,” said Michael Küppers of ESA in Spain, lead author of a paper in the journal Nature.

The results come at the right time for NASA’s Dawn mission, which is on its way to Ceres now after spending more than a year orbiting the large asteroid Vesta. Dawn is scheduled to arrive at Ceres in the spring of 2015, where it will take the closest look ever at its surface.

“We’ve got a spacecraft on the way to Ceres, so we don’t have to wait long before getting more context on this intriguing result, right from the source itself,” said Carol Raymond, the deputy principal investigator for Dawn at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Dawn will map the geology and chemistry of the surface in high resolution, revealing the processes that drive the outgassing activity.”

For the last century, Ceres was known as the largest asteroid in our solar system. But in 2006, the International Astronomical Union, the governing organization responsible for naming planetary objects, reclassified Ceres as a dwarf planet because of its large size. It is roughly 590 miles (950 kilometers) in diameter. When it first was spotted in 1801, astronomers thought it was a planet orbiting between Mars and Jupiter. Later, other cosmic bodies with similar orbits were found, marking the discovery of our solar system’s main belt of asteroids.

Scientists believe Ceres contains rock in its interior with a thick mantle of ice that, if melted, would amount to more fresh water than is present on all of Earth. The materials making up Ceres likely date from the first few million years of our solar system’s existence and accumulated before the planets formed.

Until now, ice had been theorized to exist on Ceres but had not been detected conclusively. It took Herschel’s far-infrared vision to see, finally, a clear spectral signature of the water vapor. But Herschel did not see water vapor every time it looked. While the telescope spied water vapor four different times, on one occasion there was no signature.

Here is what scientists think is happening: when Ceres swings through the part of its orbit that is closer to the sun, a portion of its icy surface becomes warm enough to cause water vapor to escape in plumes at a rate of about 6 kilograms (13 pounds) per second. When Ceres is in the colder part of its orbit, no water escapes.

The strength of the signal also varied over hours, weeks and months, because of the water vapor plumes rotating in and out of Herschel’s views as the object spun on its axis. This enabled the scientists to localize the source of water to two darker spots on the surface of Ceres, previously seen by NASA’s Hubble Space Telescope and ground-based telescopes. The dark spots might be more likely to outgas because dark material warms faster than light material. When the Dawn spacecraft arrives at Ceres, it will be able to investigate these features.

The results are somewhat unexpected because comets, the icier cousins of asteroids, are known typically to sprout jets and plumes, while objects in the asteroid belt are not.

“The lines are becoming more and more blurred between comets and asteroids,” said Seungwon Lee of JPL, who helped with the water vapor models along with Paul von Allmen, also of JPL. “We knew before about main belt asteroids that show comet-like activity, but this is the first detection of water vapor in an asteroid-like object.”

The research is part of the Measurements of 11 Asteroids and Comets Using Herschel (MACH-11) program, which used Herschel to look at small bodies that have been or will be visited by spacecraft, including the targets of NASA’s previous Deep Impact mission and upcoming Origins Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-Rex). Laurence O’ Rourke of the European Space Agency is the principal investigator of the MACH-11 program.

Herschel is a European Space Agency mission, with science instruments provided by consortia of European institutes and with important participation by NASA. While the observatory stopped making science observations in April 2013, after running out of liquid coolant, as expected, scientists continue to analyze its data. NASA’s Herschel Project Office is based at JPL. JPL contributed mission-enabling technology for two of Herschel’s three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the U.S. astronomical community.

Dawn’s mission is managed by JPL for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. in Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are international partners on the mission team. Caltech manages JPL for NASA.

More information about Herschel is online at: More information about NASA’s role in Herschel is available at: For more information about NASA’s Dawn mission, visit: