One of the biggest challenges of working and living in space is the threat posed by radiation. In addition to solar and cosmic rays that are hazardous to astronauts’ health, there is also ionizing radiation that threatens their electronic equipment. This requires that all spacecraft, satellites, and space stations that are sent to orbit be shielded using materials that are often quite heavy and/or expensive.
Looking to create alternatives, a team of engineers came up with a new technique for producing radiation shielding that is lightweight and more cost-effective than existing methods. The secret ingredient, according to their recently-published research, is metal oxides (aka. rust). This new method could have numerous applications and lead to a significant drop in the costs associated with space launches and spaceflight.
When it comes to planning missions to Mars and other distant locations in the Solar System, the threat posed by radiation has become something of an elephant in the room. Whether it is NASA’s proposed “Journey to Mars“, SpaceX’s plans to conduct regular flights to Mars, or any other plan to send crewed missions beyond Low Earth Orbit (LEO), long-term exposure to space radiation and the health risks this poses is an undeniable problem.
But as the old saying goes, “for every problem, there is a solution”; not to mention, “necessity is the mother of invention”. And as representatives from NASA’s Human Research Program recently indicated, the challenge posed by space radiation will not deter the agency from its exploration goals. Between radiation shielding and efforts aimed at mitigation, NASA plans to proceed with mission to Mars and beyond.
Since the beginning of the Space Age, scientists have understood how beyond Earth’s magnetic field, space is permeated by radiation. This includes Galactic Cosmic Rays (GCRs), Solar Particle Events (SPEs) and the Van Allen Radiation Belts, which contains trapped space radiation. Much has also been learned through the ISS, which continues to provide opportunities to study the effects of exposure to space radiation and microgravity.
For instance, though it orbits within Earth’s magnetic field, astronauts receive over ten times the amount of radiation than people experience on average here on Earth. NASA is able to protect crews from SPEs by advising them to seek shelter in more heavily shielded areas of the station – such as the Russian-built Zvezda service module or the US-built Destiny laboratory.
However, GCRs are more of a challenge. These energetic particles, which are primarily composed of high-energy protons and atomic nuclei, can come from anywhere within our galaxy and are capable of penetrating even metal. To make matters worse, when these particles cut through material, they generate a cascade reaction of particles, sending neutrons, protons and other particles in all directions.
This “secondary radiation” can sometimes be a greater risk than the GCRs themselves. And recent studies have indicated that the threat they pose to living tissue can also have a cascading effect, where damage to one cell can then spread to others. As Dr. Lisa Simonsen, a Space Radiation Element Scientist with NASA’s HRP, explained:
“One of the most challenging parts for the human journey to Mars is the risk of radiation exposure and the inflight and long-term health consequences of the exposure. This ionizing radiation travels through living tissues, depositing energy that causes structural damage to DNA and alters many cellular processes.”
To address this risk, NASA is currently evaluating various materials and concepts to shield crews from GCRs. These materials will become an integral part of future deep-space missions. Experiments involving these materials and their incorporation into transport vehicles, habitats and space suits are currently taking place at the NASA Space Radiation Laboratory (NSRL).
At the same time, NASA is also investigating pharmaceutical countermeasures, which could prove to be more effective than radiation shielding. For instance, potassium iodide, diethylenetriamine pentaacietic acid (DTPA) and the dye known as “Prussian blue” have been used for decades to treat radiation sickness. During long-term missions, astronauts will likely need to take daily doses of radiation meds to mitigate exposure to radiation.
Space radiation detection and mitigation technologies are also being developed through NASA’s Advanced Exploration Systems Division. These include the Hybrid Electronic Radiation Assessor for the Orion spacecraft, and a series of personal and operational dosimeters for the ISS. There are also existing instruments which are expected to play an important role when crewed mission to Mars begin.
Who can forget the Radiation Assessment Detector (RAD), which was one of the first instruments sent to Mars for the specific purpose of informing future human exploration efforts. This instrument is responsible for identifying and measuring radiation on the Martian surface, be it radiation from space or secondary radiation produced by cosmic rays interacting with the Martian atmosphere and surface.
Because of these and other preparations, many at NASA are naturally hopeful that the risks of space radiation can and will be addressed. As Pat Troutman, the NASA Human Exploration Strategic Analysis Lead, stated in a recent NASA press statement:
“Some people think that radiation will keep NASA from sending people to Mars, but that’s not the current situation. When we add the various mitigation techniques up, we are optimistic it will lead to a successful Mars mission with a healthy crew that will live a very long and productive life after they return to Earth.
Scientists are also engaged in ongoing studies of space weather in order to develop better forecasting tools and countermeasures. Last, but not least, multiple organizations are looking to develop smaller, faster spacecraft in order to reduce travel times (and hence, exposure to radiation). Taken together, all of these strategies are necessary for long-duration spaceflights to Mars and other locations throughout the Solar System.
Granted, there is still considerable research that needs to be done before we can say with any certainty that crewed missions to Mars and beyond will be safe, or at least not pose any unmanageable risks. But the fact that NASA is busy addressing these needs from multiple angles demonstrates how committed they are to seeing such a mission happen in the coming decades.
“Mars is the best option we have right now for expanding long-term, human presence,” said Troutman. “We’ve already found valuable resources for sustaining humans, such as water ice just below the surface and past geological and climate evidence that Mars at one time had conditions suitable for life. What we learn about Mars will tell us more about Earth’s past and future and may help answer whether life exists beyond our planet.”
Beyond the public sector, companies like SpaceX and non-profits like MarsOne are also investigating possible strategies for protecting and mitigating against space radiation. Elon Musk has been quite vocal (especially of late) about his plans to conduct regular trips to Mars in the near future using the Interplanetary Transport System (ITS) – also known as the BFR – not to mention establishing a colony on the planet.
And Baas Landsdorp has indicated that the organization he founded to establish a human presence on Mars will find ways to address the threat posed by radiation, regardless of what a certain report from MIT says! Regardless of the challenges, there is simply no shortage of people who want to see humanity go to Mars, and possibly even stay there!
And be sure to check out this video about the Human Research Program, courtesy of NASA:
New measurements of the energetic space radiation environment present in interplanetary space taken by NASA’s Curiosity rover confirm what has long been suspected – that lengthy years long voyages by astronauts to deep space destinations like Mars will expose the crews to high levels of radiation that – left unchecked – would be harmful to their health and increase their chances of developing fatal cancers.
Although the data confirm what scientists had suspected, it’s equally important to state that the space radiation data are not ‘show stoppers” for human deep space voyages to the Red Planet and other destinations because there are a multitude of counter measures- like increased shielding and more powerful propulsion – that NASA and the world’s space agencies can and must implement to reduce and mitigate the dangerous health effects of radiation on human travelers.
The new radiation data was released at a NASA media briefing on May 30 and published in the journal Science on May 31.
Indeed the new measurements collected by Curiosity’s Radiation Assessment Detector (RAD) instrument during her 253-day, 560-million- kilometer journey enroute to the Red Planet in 2011 and 2012 will provide important insights to allow NASA to start designing systems for safely conducting future human missions to Mars.
“NASA wants to send astronauts to Mars in the 2030’s,” Chris Moore, NASA’s deputy director of Advanced Exploration Systems NASA HQ, said to reporters at the media briefing.
“The Human Spaceflight and Planetary Science Divisions at NASA are working together to get the data needed for human astronauts. RAD is perfect to collect the data for that,” said Moore.
The RAD data indicate that astronauts would be exposed to radiation levels that would exceed the career limit levels set by NASA during a more than year long voyage to Mars and back using current propulsion systems, said Eddie Semones, spaceflight radiation health officer at the Johnson Space Center.
NASA’s Humans to Mars planning follows initiatives outlined by President Obama.
“As this nation strives to reach an asteroid and Mars in our lifetimes, we’re working to solve every puzzle nature poses to keep astronauts safe so they can explore the unknown and return home,” said William Gerstenmaier, NASA’s associate administrator for human exploration and operations in Washington, in a statement.
The International Space Station already in low Earth orbit and the Orion crew capsule under development will serve as very useful platforms to conduct real life experiments on resolving the health risks posed by long term exposure to space radiation.
“We learn more about the human body’s ability to adapt to space every day aboard the International Space Station, said Gerstenmaier. “As we build the Orion spacecraft and Space Launch System rocket to carry and shelter us in deep space, we’ll continue to make the advances we need in life sciences to reduce risks for our explorers. Curiosity’s RAD instrument is giving us critical data we need so that we humans, like the rover, can dare mighty things to reach the Red Planet.”
RAD was the first instrument to collect radiation measurements during the cruise phase to the Red Planet. It is mounted on the top deck of the Curiosity rover.
“Although RAD’s objective is to characterize the radiation environment on the surface of Mars, it’s also good for the cruise phase,” Don Hassler, RAD Principal Investigator at the Southwest Research Institute (SWRI) told reporters.
“Since Orion and MSL are similar sized RAD is ideal for collecting the data.”
Hassler explained that RAD measures two types of radiation that pose health risks to astronauts. First, the steady stream of low dose galactic cosmic rays (GCRs), and second the short-term and unpredictable exposures to solar energetic particles (SEPs) arising from solar flares and coronal mass ejections (CME’s).
Radiation exposure is known to increase a person’s risk of suffering fatal cancer.
Exposure is measured in units of Sievert (Sv) or milliSievert (one one-thousandth Sv). Being exposed to a dose of 1 Sievert (Sv) over time results in a five percent increased risk of developing cancer.
NASA’s current regulations limit the potential for increased cancer risk to 3 percent for astronauts currently working on the ISS in low-Earth orbit.
RAD determined that the Curiosity rover was exposed to an average of 1.8 milliSieverts per day during the 8.5 month cruise to Mars, due mostly to Galactic Cosmic Rays, said Cary Zeitlin, SWRI Principal Scientist for MSL,at the briefing. “Solar particles only accounted for about 3 to 5 percent of that.”
During a typical 6 month cruise to Mars the astronaut crews would be exposed to 330 millisieverts. That is more than 3 times the typical 6 month exposure of astronauts aboard the ISS which amounts to about 100 millisieverts. See graphic above.
“The 360 day interplanetary round trip exposure would be 660 millisieverts based on chemical propulsion methods,” Zeitlin told Universe Today. “A 500 day mission would increase that to 900 millisieverts.”
By comparison, the average annual exposure for a typical person in the US from all radiation sources is less than 10 millisieverts.
The Earth’s magnetic field provides partial radiation shielding for the ISS astronauts living in low-Earth orbit.
“In terms of accumulated dose, it’s like getting a whole-body CT scan once every five or six days,” says Zeitlin.
And that round trip dose of 660 millisieverts doesn’t even include the astronauts surface stay on Mars – which would significantly raise the total exposure count. But luckily for the crew the surface radiation is less.
“The radiation environment on the surface of Mars is about half that in deep space since its modified by the atmosphere,” Hassler told Universe Today. “We will publish the surface data in a few months.”
NASA will need to decide whether to reassess the acceptable career limits for astronauts exposure to radiation from galactic cosmic rays and solar particle events during long duration deep space journeys.
Panoramic view of Yellowknife Bay basin back dropped by Mount Sharp shows the location of the first two drill sites – John Klein & Cumberland – targeted by NASA’s Curiosity Mars rover and the RAD radiation detector which took the first deep space measurements of harmful space radiation during the cruise phase to Mars in 2011 and 2012 . Curiosity accomplished historic 1st drilling into Martian rock at John Klein outcrop on Feb 8, 2013 (Sol 182) near where the robotic arm is touching the surface. This week the rover scooted about 9 feet to the right to Cumberland (right of center) for 2nd drill campaign on May 19, 2013 (Sol 279). Credit: NASA/JPL-Caltech/Ken Kremer – kenkremer.com/Marco Di Lorenzo
And don’t forget to “Send Your Name to Mars” aboard NASA’s MAVEN orbiter- details here. Deadline: July 1, 2013
Image caption: Curiosity is taking the first ever radiation measurements from the surface of another planet in order to determine if future human explorers can live on Mars – as she traverses the terrain of the Red Planet. Curiosity is looking back to her rover tracks and the foothills of Mount Sharp and the eroded rim of Gale Crater in the distant horizon on Sol 24 (Aug. 30, 2012). This panorama is featured on PBS NOVA ‘Ultimate Mars Challenge’ documentary which premiered on PBS TV on Nov. 14. RAD is located on the rover deck in this colorized mosaic stitched together from Navcam images by the image processing team of Ken Kremer & Marco Di Lorenzo. Credit: NASA / JPL-Caltech / Ken Kremer / Marco Di Lorenzo
Metallic robots constructed by ingenious humans can survive on Mars. But what about future human astronauts?
NASA’s plucky Mars Exploration Rover Opportunity has thrived for nearly a decade traversing the plains of Meridiani Planum despite the continuous bombardment of sterilizing cosmic and solar radiation from charged particles thanks to her radiation hardened innards.
How about humans? What fate awaits them on a bold and likely year’s long expedition to the endlessly extreme and drastically harsh environment on the surface of the radiation drenched Red Planet – if one ever gets off the ground here on Earth? How much shielding would people need?
Answering these questions is one of the key quests ahead for NASA’s SUV sized Curiosity Mars rover – now 100 Sols, or Martian days, into her 2 year long primary mission phase.
Preliminary data looks promising.
Curiosity survived the 8 month interplanetary journey and the unprecedented sky crane rocket powered descent maneuver to touch down safely inside Gale Crater beside the towering layered foothills of 3 mi. (5.5 km) high Mount Sharp on Aug. 6, 2012.
Now she is tasked with assessing whether Mars and Gale Crater ever offered a habitable environment for microbial life forms – past or present. Characterizing the naturally occurring radiation levels stemming from galactic cosmic rays and the sun will address the habitability question for both microbes and astronauts. Radiation can destroy near-surface organic molecules.
Researchers are using Curiosity’s state-of-the-art Radiation Assessment Detector (RAD) instrument to monitor high-energy radiation on a daily basis and help determine the potential for real life health risks posed to future human explorers on the Martian surface.
“The atmosphere provides a level of shielding, and so charged-particle radiation is less when the atmosphere is thicker,” said RAD Principal Investigator Don Hassler of the Southwest Research Institute in Boulder, Colo. See the data graphs herein.
“Absolutely, the astronauts can live in this environment. It’s not so different from what astronauts might experience on the International Space Station. The real question is if you add up the total contribution to the astronaut’s total dose on a Mars mission can you stay within your career limits as you accumulate those numbers. Over time we will get those numbers,” Hassler explained.
The initial RAD data from the first two months on the surface was revealed at a media briefing for reporters on Thursday, Nov. 15 and shows that radiation is somewhat lower on Mars surface compared to the space environment due to shielding from the thin Martian atmosphere.
Image caption: Longer-Term Radiation Variations at Gale Crater. This graphic shows the variation of radiation dose measured by the Radiation Assessment Detector on NASA’s Curiosity rover over about 50 sols, or Martian days, on Mars. (On Earth, Sol 10 was Sept. 15 and Sol 60 was Oct. 6, 2012.) The dose rate of charged particles was measured using silicon detectors and is shown in black. The total dose rate (from both charged particles and neutral particles) was measured using a plastic scintillator and is shown in red. Credit: NASA/JPL-Caltech/ SwRI
RAD hasn’t detected any large solar flares yet from the surface. “That will be very important,” said Hassler.
“If there was a massive solar flare that could have an acute effect which could cause vomiting and potentially jeopardize the mission of a spacesuited astronaut.”
“Overall, Mars’ atmosphere reduces the radiation dose compared to what we saw during the cruise to Mars by a factor of about two.”
RAD was operating and already taking radiation measurements during the spacecraft’s interplanetary cruise to compare with the new data points now being collected on the floor of Gale Crater.
Mars atmospheric pressure is a bit less than 1% of Earth’s. It varies somewhat in relation to atmospheric cycles dependent on temperature and the freeze-thaw cycle of the polar ice caps and the resulting daily thermal tides.
“We see a daily variation in the radiation dose measured on the surface which is anti-correlated with the pressure of the atmosphere. Mars atmosphere is acting as a shield for the radiation. As the atmosphere gets thicker that provides more of a shield. Therefore we see a dip in the radiation dose by about 3 to 5%, every day,” said Hassler.
Image Caption: Curiosity Self Portrait with Mount Sharp at Rocknest ripple in Gale Crater. Curiosity used the Mars Hand Lens Imager (MAHLI) camera on the robotic arm to image herself and her target destination Mount Sharp in the background. Mountains in the background to the left are the northern wall of Gale Crater. This color panoramic mosaic was assembled from raw images snapped on Sol 85 (Nov. 1, 2012). Credit: NASA/JPL-Caltech/MSSS/Ken Kremer/Marco Di Lorenzo
There are also seasonal changes in radiation levels as Mars moves through space.
The RAD team is still refining the radiation data points.
“There’s calibrations and characterizations that we’re finalizing to get those numbers precise. We’re working on that. And we’re hoping to release that at the AGU [American Geophysical Union] meeting in December.”
Image caption: Daily Cycles of Radiation and Pressure at Gale Crater. This graphic shows the daily variations in Martian radiation and atmospheric pressure as measured by NASA’s Curiosity rover. As pressure increases, the total radiation dose decreases. When the atmosphere is thicker, it provides a better barrier with more effective shielding for radiation from outside of Mars. At each of the pressure maximums, the radiation level drops between 3 to 5 percent. The radiation level goes up at the end of the graph due to a longer-term trend that scientists are still studying. Credit: NASA/JPL-Caltech/SwRI
Radiation is a life limiting factor to habitability. RAD is the first science instrument to directly measure radiation from the surface of a planet other than Earth.
“Curiosity is finding that the radiation environment on Mars is sensitive to Mars weather and climate,” Hassler concluded.
Unlike Earth, Mars lost its magnetic field some 3.5 billion years ago – and therefore most of its shielding capability from harsh levels of energetic particle radiation from space.
Much more data will need to be collected by RAD before any final conclusions on living on Mars, and for how long and in which type habitats, can be drawn.
Learn more about Curiosity and NASA missions at my upcoming free public presentations:
Dec 6: Free Public lecture titled “Atlantis, The Premature End of America’s Shuttle Program and What’s Beyond for NASA” including Curiosity, Orion, SpaceX and more by Ken Kremer at Brookdale Community College/Monmouth Museum and STAR Astronomy club in Lincroft, NJ at 8 PM
Barely two weeks into the 8 month journey to the Red Planet, NASA’sCuriosity Mars Science Lab (MSL) rover was commanded to already begin collecting the first science of the mission by measuring the ever present radiation environment in space.
Engineers powered up the MSL Radiation Assessment Detector (RAD) that monitors high-energy atomic and subatomic particles from the sun, distant supernovas and other sources.
RAD is the only one of the car-sized Curiosity’s 10 science instrument that will operate both in space as well as on the Martian surface. It will provide key data that will enable a realistic assessment of the levels of lethal radiation that would confront any potential life forms on Mars as well as Astronauts voyaging between our solar systems planets.
“RAD is the first instrument on Curiosity to be turned on. It will operate throughout the long journey to Mars,” said Don Hassler, RAD’s principal investigator from the Southwest Research Institute in Boulder, Colo.
These initial radiation measurements are focused on illuminating possible health effects facing future human crews residing inside spaceships.
Video Caption: The Radiation Assessment Detector is the first instrument on Curiosity to begin science operations. It was powered up and began collecting data on Dec. 6, 2011. Credit: NASA
“We want to characterize the radiation environment inside the spacecraft because it’s different from the radiation environment measured in interplanetary space,” says Hassler.
RAD is located on the rover which is currently encapsulated within the protective aeroshell. Therefore the instrument is positioned inside the spacecraft, simulating what it would be like for an astronaut with some shielding from the external radiation, measuring energetic particles.
“The radiation hitting the spacecraft is modified by the spacecraft, it gets changed and produces secondary particles. Sometimes those secondary particles can be more damaging than the primary radiation itself.”
“What’s new is that RAD will measure the radiation inside the spacecraft, which will be very similar to the environment that a future astronaut might see on a future mission to Mars.”
Curiosity’s purpose is to search for the ingredients of life and assess whether the rovers landing site at Gale Crater could be or has been favorable for microbial life.
The Martian surface is constantly bombarded by deadly radiation from space. Radiation can destroy the very organic molecules which Curiosity seeks.
“After Curiosity lands, we’ll be taking radiation measurements on the surface of another planet for the first time,” notes Hassler.
RAD was built by a collaboration of the Southwest Research Institute, together with Christian Albrechts University in Kiel, Germany with funding from NASA’s Human Exploration Directorate and Germany’s national aerospace research center, Deutsches Zentrum für Luft- und Raumfahrt.
“What Curiosity might find could be a game-changer about the origin and evolution of life on Earth and elsewhere in the universe,” said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. “One thing is certain: The rover’s discoveries will provide critical data that will impact human and robotic planning and research for decades.”
Curiosity was launched from Florida on Nov. 26. After sailing on a 254 day and 352-million-mile (567-million-kilometer) interplanetary flight from the Earth to Mars, Curiosity will smash into the atmosphere at 13,000 MPH on August 6, 2012 and pioneer a nail biting and first-of-its-kind precision rocket powered descent system to touchdown inside layered terrain at Gale Crater astride a 3 mile (5 km) high mountain that may have preserved evidence of ancient or extant Martian life.
Miraculously, NASA’s Opportunity Mars rover and onboard instruments and cameras have managed to survive nearly 8 years of brutally harsh Martian radiation and arctic winters.
The huge solar-powered Juno spacecraft will skim to within 4800 kilometers (3000 miles) of the cloud tops of Jupiter to study the origin and evolution of our solar system’s largest planet. Understanding the mechanism of how Jupiter formed will lead to a better understanding of the origin of planetary systems around other stars throughout our galaxy.
Juno will be spinning like a windmill as it fly’s in a highly elliptical polar orbit and investigates the gas giant’s origins, structure, atmosphere and magnetosphere with a suite of nine science instruments.
During the five year cruise to Jupiter, the 3,600 kilogram probe will fly by Earth once in 2013 to pick up speed and accelerate Juno past the asteroid belt on its long journey to the Jovian system where it arrives in July 2016.
Juno will orbit Jupiter 33 times and search for the existence of a solid planetary core, map Jupiter’s intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet’s auroras.
The mission will provide the first detailed glimpse of Jupiter’s poles and is set to last approximately one year. The elliptical orbit will allow Juno to avoid most of Jupiter’s harsh radiation regions that can severely damage the spacecraft systems.
Juno was designed and built by Lockheed Martin Space Systems, Denver, and air shipped in a protective shipping container inside the belly of a U.S. Air Force C-17 Globemaster cargo jet to the Astrotech payload processing facility in Titusville, Fla.
This week the spacecraft begins about four months of final functional testing and integration inside the climate controlled clean room and undergoes a thorough verification that all its systems are healthy. Other processing work before launch includes attachment of the long magnetometer boom and solar arrays which arrived earlier.
Juno is the first solar powered probe to be launched to the outer planets and operate at such a great distance from the sun. Since Jupiter receives 25 times less sunlight than Earth, Juno will carry three giant solar panels, each spanning more than 20 meters (66 feet) in length. They will remain continuously in sunlight from the time they are unfurled after launch through the end of the mission.
“The Juno spacecraft and the team have come a long way since this project was first conceived in 2003,” said Scott Bolton, Juno’s principal investigator, based at Southwest Research Institute in San Antonio, in a statement. “We’re only a few months away from a mission of discovery that could very well rewrite the books on not only how Jupiter was born, but how our solar system came into being.”
Juno is slated to launch aboard the most powerful version of the Atlas V rocket – augmented by 5 solid rocket boosters – from Cape Canaveral, Fla. on August 5. The launch window extends through August 26. Juno is the second mission in NASA’s New Frontiers program.
NASA’s Mars Curiosity Rover will follow Juno to the Atlas launch pad, and is scheduled to liftoff in late November 2011. Read my stories about Curiosity here and here.
Because of cuts to NASA’s budget by politicians in Washington, the long hoped for mission to investigate the Jovian moon Europa may be axed, along with other high priority science missions. Europa may harbor subsurface oceans of liquid water and is a prime target in NASA’s search for life beyond Earth.