Posted on by Nancy Atkinson

The Mars Landing Approach: Getting Large Payloads to the Surface of the Red Planet

The first true-colour image of Mars from ESA’s Rosetta generated using the OSIRIS orange (red), green and blue colour filters. The image was acquired on 24 February 2007 at 19:28 CET from a distance of about 240 000 km. Credit: MPS for OSIRIS Team MPS/UPD/LAM/ IAA/ RSSD/ INTA/ UPM/ DASP/ IDA

Some proponents of human missions to Mars say we have the technology today to send people to the Red Planet. But do we? Rob Manning of the Jet Propulsion Laboratory discusses the intricacies of entry, descent and landing and what needs to be done to make humans on Mars a reality.

There’s no comfort in the statistics for missions to Mars. To date over 60% of the missions have failed. The scientists and engineers of these undertakings use phrases like “Six Minutes of Terror,” and “The Great Galactic Ghoul” to illustrate their experiences, evidence of the anxiety that’s evoked by sending a robotic spacecraft to Mars — even among those who have devoted their careers to the task. But mention sending a human mission to land on the Red Planet, with payloads several factors larger than an unmanned spacecraft and the trepidation among that same group grows even larger. Why?

Nobody knows how to do it.

Surprised? Most people are, says Rob Manning the Chief Engineer for the Mars Exploration Directorate and presently the only person who has led teams to land three robotic spacecraft successfully on the surface of Mars.

“It turns out that most people aren’t aware of this problem and very few have worried about the details of how you get something very heavy safely to the surface of Mars,” said Manning.

He believes many people immediately come to the conclusion that landing humans on Mars should be easy. After all, humans have landed successfully on the Moon and we can land our human-carrying vehicles from space to Earth. And since Mars falls between the Earth and the Moon in size, and also in the amount of atmosphere it has then the middle ground of Mars should be easy. “There’s the mindset that we should just be able to connect the dots in between,” said Manning.

But as of now, the dots will need to connect across a large abyss.

“We know what the problems are. I like to blame the god of war,” quipped Manning. “This planet is not friendly or conducive for landing.”

The real problem is the combination of Mars’ atmosphere and the size of spacecraft needed for human missions. So far, our robotic spacecraft have been small enough to enable at least some success in reaching the surface safely. But while the Apollo lunar lander weighed approximately 10 metric tons, a human mission to Mars will require three to six times that mass, given the restraints of staying on the planet for a year. Landing a payload that heavy on Mars is currently impossible, using our existing capabilities. “There’s too much atmosphere on Mars to land heavy vehicles like we do on the moon, using propulsive technology completely,” said Manning, “and there’s too little atmosphere to land like we do on Earth. So, it’s in this ugly, grey zone.”

But what about airbags, parachutes, or thrusters that have been used on the previous successful robotic Mars missions, or a lifting body vehicle similar to the space shuttle?

None of those will work, either on their own or in combination, to land payloads of one metric ton and beyond on Mars. This problem affects not only human missions to the Red Planet, but also larger robotic missions such as a sample return. “Unfortunately, that’s where we are,” said Manning. “Until we come up with a whole new trick, a whole new system, landing humans on Mars will be an ugly and scary proposition.”

Road Mapping
In 2004 NASA organized a Road Mapping session to discuss the current capabilities and future problems of landing humans on Mars. Manning co-chaired this event along with Apollo 17 astronaut Harrison Schmitt and Claude Graves, who has since passed away, from the Johnson Space Center. Approximately 50 other people from across NASA, academia and industry attended the session. “At that time the ability to explain these problems in a coherent way was not as good,” said Manning. “The entry, descent and landing process is actually made up of people from many different disciplines. Very few people really understood, especially for large scale systems, what all of the issues were. At the Road Mapping session we were able to put them all down and talk about them.”

The major conclusion that came from the session was that no one has yet figured out how to safely get large masses from speeds of entry and orbit down to the surface of Mars. “We call it the Supersonic Transition Problem,” said Manning. “Unique to Mars, there is a velocity-altitude gap below Mach 5. The gap is between the delivery capability of large entry systems at Mars and the capability of super-and sub-sonic decelerator technologies to get below the speed of sound.”

Plainly put, with our current capabilities, a large, heavy vehicle, streaking through Mars’ thin, volatile atmosphere only has about ninety seconds to slow from Mach 5 to under Mach 1, change and re-orient itself from a being a spacecraft to a lander, deploy parachutes to slow down further, then use thrusters to translate to the landing site and finally, gently touch down.

No Airbags
When this problem is first presented to people, the most offered solution, Manning says, is to use airbags, since they have been so successful for the missions that he has been involved with; the Pathfinder rover, Sojourner and the two Mars Exploration Rovers (MER), Spirit and Opportunity.

But engineers feel they have reached the capacity of airbags with MER. “It’s not just the mass or the volume of the airbags, or the size of the airbags themselves, but it’s the mass of the beast inside the airbags,” Manning said. “This is about as big as we can take that particular design.”

In addition, an airbag landing subjects the payload to forces between 10-20 G’s. While robots can withstand such force, humans can’t. This doesn’t mean airbags will never be used again, only that airbag landings can’t be used for something human or heavy.

Even the 2009 Mars Science Laboratory (MSL) rover, weighing 775 kilograms (versus MER at 175.4 kilograms each) requires an entirely new landing architecture. Too massive for airbags, the small-car sized rover will use a landing system dubbed the Sky Crane. “Even though some people laugh when they first see it, my personal view is that the Sky Crane is actually the most elegant system we’ve come up with yet, and the simplest,” said Manning. MSL will use a combination of a rocket-guided entry with a heat shield, a parachute, then thrusters to slow the vehicle even more, followed by a crane-like system that lowers the rover on a cable for a soft landing directly on its wheels. Depending on the success of the Sky Crane with MSL, it’s likely that this system can be scaled for larger payloads, but probably not the size needed to land humans on Mars.

Atmospheric Anxiety and Parachute Problems
“The great thing about Earth,” said Manning “is the atmosphere.” Returning to Earth and entering the atmosphere at speeds between 7-10 kilometers per second, the space shuttle, Apollo and Soyuz capsules and the proposed Crew Exploration Vehicle (CEV) will all decelerate to less than Mach 1 at about twenty kilometers above the ground just by skimming through Earth’s luxuriously thick atmosphere and using a heat shield. To reach slower speeds needed for landing, either a parachute is deployed, or in the case of the space shuttle, drag and lift allow the remainder of the speed to bleed away.

But Mars’ atmosphere is only one per cent as dense as Earth’s. For comparison, Mars atmosphere at its thickest is equivalent to Earth’s atmosphere at about 35 kilometers above the surface The air is so thin that a heavy vehicle like a CEV will basically plummet to the surface; there’s not enough air resistance to slow it down sufficiently. Parachutes can only be opened at speeds less than Mach 2, and a heavy spacecraft on Mars would never go that slow by using just a heat shield. “And there are no parachutes that you could use to slow this vehicle down,” said Manning. “That’s it. You can’t land a CEV on Mars unless you don’t mind it being a crater on the surface.”

That’s not good news for the Vision for Space Exploration. Would a higher lift vehicle like the space shuttle save the day? “Well, on Mars, when you use a very high lift to weight to drag ratio like the shuttle,” said Manning, “in order to get good deceleration and use the lift properly, you’d need to cut low into the atmosphere. You’d still be going at Mach 2 or 3 fairly close to the ground. If you had a good control system you could spread out your deceleration to lengthen the time you are in the air. You’d eventually slow down to under Mach 2 to open a parachute, but you’d be too close to the ground and even an ultra large supersonic parachute would not save you.”

Supersonic parachute experts have concluded that to sufficiently slow a large shuttle-type vehicle on Mars and reach the ground at reasonable speeds would require a parachute one hundred meters in diameter.

“That’s a good fraction of the Rose Bowl. That’s huge,” said Manning. “We believe there’s no way to make a 100-meter parachute that can be opened safely supersonically, not to mention the time it takes to inflate something that large. You’d be on the ground before it was fully inflated. It would not be a good outcome.”

Heat Shields and Thrusters

It’s not that Mars’ atmosphere is useless. Manning explained that with robotic spacecraft, 99% of the kinetic energy of an incoming vehicle is taken away using a heat shield in the atmosphere. “It’s not inconceivable that we can design larger, lighter heat shields,” he said, “but the problem is that right now the heat shield diameter for a human-capable spacecraft overwhelms any possibility of launching that vehicle from Earth.” Manning added that it would almost be better if Mars were like the moon, with no atmosphere at all.

If that were the case, an Apollo-type lunar lander with thrusters could be used. “But that would cause another problem,” said Manning, “in that for every kilogram of stuff in orbit, it takes twice as much fuel to get to the surface of Mars as the moon. Everything is twice as bad since Mars is about twice as big as the moon.” That would entail a large amount of fuel, perhaps over 6 times the payload mass in fuel, to get human-sized payloads to the surface, all of which would have to be brought along from Earth. Even on a fictitious air-less Mars that is not an option.

But using current thruster technology in Mars’ real, existing atmosphere poses aerodynamic problems. “Rocket plumes are notoriously unstable, dynamic, chaotic systems,” said Manning. “Basically flying into the plume at supersonics speeds, the rocket plume is acting like a nose cone; a nose cone that’s moving around in front of you against very high dynamic pressure. Even though the atmospheric density is very low, because the velocity is so high, the forces are really huge.”

Manning likened theses forces to a Category Five hurricane. This would cause extreme stress, with shaking and twisting that would likely destroy the vehicle. Therefore using propulsive technology alone is not an option.

Using thrusters in combination with a heat shield and parachute also poses challenges. Assuming the vehicle has used some technique to slow to under Mach 1, using propulsion just in last stages of descent to gradually adjust the lander’s trajectory would enable the vehicle to arrive very precisely at the desired landing site. “We’re looking at firing thrusters less than 1 kilometer above the ground. Your parachute has been discarded, and you see that you are perhaps 5 kilometers south of where you want to land,” said Manning. “So now you need the ability to turn the vehicle over sideways to try to get to your landing spot. But this may be an expensive option, adding a large tax in fuel to get to the desired landing rendezvous point.”

Additionally, on the moon, with no atmosphere or weather, there is nothing pushing against the vehicle, taking it off target, and a la Neil Armstrong on Apollo 11, the pilot can “fly out the uncertainties” as Manning called it, to reach a suitable or desired landing site. On Mars, however, the large variations in the density of the atmosphere coupled with high and unpredictable winds conspire to push vehicles off course. “We need to have ways to fight those forces or ways to make up for any mis-targeting using the propulsion system,” said Manning. “Right now, we don’t have that ability and we’re a long way from making it happen.”

Supersonic Decelerators

The best hope on the horizon for making the human enterprise on Mars possible is a new type of supersonic decelerator that’s only on the drawing board. A few companies are developing a new inflatable supersonic decelerator called a Hypercone.

Imagine a huge donut with a skin across its surface that girdles the vehicle and inflates very quickly with gas rockets (like air bags) to create a conical shape. This would inflate about 10 kilometers above the ground while the vehicle is traveling at Mach 4 or 5, after peak heating. The Hypercone would act as an aerodynamic anchor to slow the vehicle to Mach 1.

Glen Brown, Chief Engineer at Vertigo, Inc. in Lake Elsinore, California was also a participant in the Mars Road Mapping session. Brown says Vertigo has been doing extensive analysis of the Hypercone, including sizing and mass estimates for landers from four to sixty metric tons. “A high pressure inflatable structure in the form a of a torus is a logical way to support a membrane in a conical shape, which is stable and has high drag at high Mach numbers,” Brown said, adding that the structure would likely be made of a coated fabric such as silicon-Vectran matrix materials. Vertigo is currently competing for funding from NASA for further research, as the next step, deployment in a supersonic wind tunnel, is quite expensive.

The structure would need to be about thirty to forty meters in diameter. The problem here is that large, flexible structures are notoriously difficult to control. At this point in time there are also several other unknowns of developing and using a Hypercone.

One train of thought is that if the Hypercone can get the vehicle under Mach 1, then subsonic parachutes could be used, much like the ones employed by Apollo, or that the CEV is projected to use to land on Earth. However, it takes time for the parachutes to inflate, and subsequently there would only be a matter of seconds of use, allowing time to shed the parachutes before converting to a propulsive system.

“You’d also need to use thrusters,” said Manning. “You’re falling 10 times faster because the density of Mars’ atmosphere is 100 times less than Earth’s. That means that you can’t just land with parachutes and touch the ground. You’d break people’s bones, if not the hardware. So you need to transition from a parachute system to an Apollo-like lunar legged lander sometime before you get to the ground.”

Manning believes that those who are immersed in these matters, like himself, see the various problems fighting each other. “It’s hard to get your brain around all these problems because all the pieces connect in complex ways,” he said. “It’s very hard to see the right answer in your mind’s eye.”

The additional issues of creating new lightweight but strong shapes and structures, with the ability to come apart and transform from one stage to another at just the right time means developing a rapid-fire Rube Goldberg-like contraption.

“The honest truth of the matter,” said Manning, “is that we don’t have a standard canonical form, a standard configuration of systems that allows us to get to the ground, with the right size that balances the forces, the loads, the people, and allows us to do all the transformation that needs to be done in the very small amount of time that we have to land.”

Other Options and Issues

Another alternative discussed at the 2004 Mars Road Mapping session was the space elevator.

“Mars is really begging for a space elevator,” said Manning. “I think it has great potential. That would solve a lot of problems, and Mars would be an excellent platform to try it.” But Manning admitted that the technology needed to suspend a space elevator has not yet been invented. The issues with space elevator technology may be vast, even compared with the challenges of landing.

Despite these known obstacles, there are few at NASA currently spending any quality time working on any of the issues of landing humans on Mars.

Manning explained, “NASA does not yet have the resources to solve this problem and also develop the CEV, complete the International Space Station and do the lunar landing systems development at the same time. But NASA knows that this is on its plate of things to do in the future and is just beginning to get a handle on the needed technology developments. I try to go out of my way to tell this story because I’m encouraging young aeronautical engineering students, particularly graduate students, to start working on this problem on their own. There is no doubt in my mind that with their help, we can figure out how to make reliable human-scale landing systems work on Mars.”

While there is much interest throughout NASA and the space sector to try to tackle these issues in the ensuing years, technology also needs a few more years to catch up to our dreams of landing humans on Mars.

And this story, like all good engineering stories, will inevitably read like a good detective novel with technical twist and turns, scientific intrigue, and high adventure on another world.

Posted on by Nancy Atkinson

STS-115 Brings More Power to the Station

STS-115 is an ambitious mission that returns the focus of human spaceflight to building the International Space Station, bringing new capabilities to the ISS. While a song by John Lennon asserts that revolution will bring power to the people, it will be a new set of solar arrays and its ability for rotation that will provide more power to the space station.
Continue reading “STS-115 Brings More Power to the Station”

Posted on by Nancy Atkinson

The NASA Science Missions Getting Cut

Artist illustration of the Dawn mission, now cancelled. Image credit: NASA/JPL. Click to enlarge.
With the release NASA’s 2007 budget request, it was clear that the productive science programs will be paying the price for the new Vision for Space Exploration, returning humans to the Moon and then sending them on to Mars. Many programs will be affected. We review the missions, what they were supposed to accomplish, and what the cuts will bring. It’s not a pretty picture.

Scientists, space interest groups, and even members of Congress have expressed so much concern about NASA’s $16.79 billion budget request for Fiscal Year 2007 that the Associate Administrator of NASA’s Science Directorate has reportedly agreed to review the proposed cuts in science and solar system exploration programs. According to the American Association for the Advancement of Science and their magazine Science, NASA will re-evaluate the missions and programs that are under threat of being cancelled or delayed.

The outcry over the budget proposal began immediately after it was released on February 6. At first glance, the 2007 budget would be an overall increase of 3.2% over the FY06 appropriation, or a 1.5% increase when including Katrina funding in Fiscal Year 2006. But while the proposed budget will support the space shuttle and space stations programs in addition to the emerging costs of the Vision for Space Exploration, it does so while slashing the funds needed to sustain the current and anticipated programs in science and exploration.

Central to the problems of this budget is that the space shuttle program has a projected $3 – 5 billion shortfall for the planned 17 missions before the shuttle is to be retired in approximately 2010. To alleviate that shortage, NASA is planning to shift $3 billion from planetary exploration and science over the next four years to pay for the manned missions.

The Planetary Society has said that what NASA is doing is essentially transferring funds from a popular and highly productive program (science) to one that is scheduled for termination (the space shuttle).

“I am extremely uneasy about this budget,” said U.S. House Science Committee Chairman Sherwood Boehlert from New York. “This budget is bad for space science, worse for earth science, perhaps worse still for aeronautics. It basically cuts or deemphasizes every forward looking, truly futuristic program of the agency to fund operational and development programs to enable us to do what we are already doing or have done before.”

Senator Pete Domenici from New Mexico and 59 other senators have introduced a bill to authorize a 10 percent increase per year in NASA’s science budget from now through 2013.

But Louis Friedman, Executive Director of the Planetary Society doesn’t anticipate any big changes in what Congress will approve for NASA. “I think it is unlikely that NASA will get very much of an increase in budget, but I do anticipate some give and take and perhaps some restoration of science funding,” he said. “We will be trying very hard for a major restoration of funding, but it will be a difficult fight.”

The budget shows a 1.5% increase in science funding for this year, and 1% increase for each of the following two years, before inflation is taken into consideration. But even with that increase, there will actually be $2 billion less for space science and $1.5 billion less for exploration that what was previously planned, and needed, for all of the missions to continue.

Following are some of the areas that would be affected:
– Research and analysis: 15% across-the-board cuts in grants for research, ($350 to $400 million over the next five years) with some retroactive to 2006. An official at NASA Headquarters said he wasn’t aware that any notices of specific research cuts have been issued at this time.
– Astrobiology research alone will have 50% of funding slashed.
– Astronomy and astrophysics at NASA cut by 20% over 5 years
– Aeronautics: cut by 18.1%, down to $724.4 million

In a press conference, NASA Administrator Mike Griffin acknowledged that “science and exploration are each paying to help complete our pre-existing obligations to the space station and the space shuttle, and when those obligations are completed the other major pieces of our portfolio will be able to do better.” In his congressional testimony, Griffin said, “I truly wish that it could be otherwise, but there is only so much money.”

NASA has 50 science and planetary missions currently operating, which includes missions from Voyager to the all of the Earth orbiting satellites to the recently launched New Horizons mission to Pluto. There are 22 missions that are in development, and 19 being studied for development. The budget maintains all of these missions, with the exception of some delays in launches to upgrade or replace existing Earth orbiting satellites. Following are missions that, if the current budget proposal is approved, will be cancelled or delayed:

Dawn: Cancelled.
The mission: Using an ion engine, the spacecraft would have traveled to the asteroid belt to study two dissimilar asteroids to help determine the role that size and water play in planetary evolution. It also would have helped determine the origin and evolution of our solar system. According to the NASA Watch website, 98% of Dawn’s hardware is complete, with a majority of it already integrated into the spacecraft. The shutdown costs for Dawn are $10 million, while it would take $40 million to complete the spacecraft and fly the mission.

In a statement, JPL Director Dr. Charles Elachi said, “During development a number of implementation and technical challenges led to a cost increase estimate of approximately 20% (from $373.2M to $446.5M.) Even though all the technical issues could be resolved, additional funding is still needed to complete and launch the mission by the spring of 2007. Of course we are disappointed, but the current tight budget environment has led to its cancellation.”

NASA has defended the cancellation not as a budget cut, but as a management decision due to developmental problems with the project. Louis Friedman says, “Indeed, (Dawn’s) cancellation was made separate from the budget submission and is not addressed in the Fiscal Year 2007 budget proposal. But the timing of the cancellation is suspicious – made immediately after the budget hearing in which testimony was unanimous that making mission cancellations in order to beef up research an analysis funding was an acceptable allocation of priorities.”

SOFIA (Stratospheric Observatory for Infrared Astronomy): Cancelled.
The mission: An airborne observatory consisting of a 2.5 meter reflecting infrared telescope. It would facilitate in developing observational techniques, new instrumentations, and in education of young scientists and teachers. The telescope is fully installed in a 747 aircraft and is functional. The first test flights for the observatory would have been done this year. SOFIA was being conducted in cooperation with the DLR, the German Aerospace Center, and was part of NASA’s Origins Program.

Mission to Europa: Cancelled.
Friedman said that the Europa mission was not yet an approved mission, but preliminary work had started and Congress had directed NASA to do that work in anticipation of a Fiscal Year 2007 new start for this mission. Instead NASA cancelled the existing work and ignored the request for a FY ’07 new start.

Last year, the Jupiter Icy Moon Orbiter was put down, which would have used a nuclear reactor to power an ion engine to send an orbiter to 3 of Jupiter’s moons. This year future missions to Europa have been tabled, even though the National Academy of Sciences and internal NASA advisory committees have endorsed the exploration of Europa as the next highest priority solar system objective after Mars.

Terrestrial Planet Finder: Cancelled.
The proposed mission: Terrestrial Planet Finder would have consisted of two complementary observatories: a visible-light coronagraph and a formation-flying infrared interferometer. It would study extra-solar planets, from their formation and development in disks of dust and gas around newly forming stars to studying features of planets and determining suitability for containing life.

TPF was not yet an approved mission, but preliminary development work had begun. NASA cancelled that work and removed TPF from the list of missions to be started in the next four years.

SIM Planet Quest: Delayed.
Formerly called the Space Interferometry Mission. As an optical interferometer in an Earth-trailing orbit, the spacecraft would survey approximately 100 of our closest stars and identify potential habitable planets. It would also survey thousands of other stars to help our general understanding of the formation and evolution of planetary systems. Also would help to answer questions in astrophysics concerning dark matter, black holes and the mass of the universe.

Mars Sample Return Mission: Delayed Indefinitely.
Not yet an approved mission, but preliminary development had begun. An exciting if not controversial mission to bring Martian soil to Earth.

Additional Programs Affected
Two Mars Scout missions planned for after 2011 were removed from the four year planning budget. These missions may have included airborne vehicles such as airplanes or balloons and small landers.

The Explorer Program, which launches small spacecraft to study areas such as Heliophysics and Astrophysics would be cut drastically with the earliest launch coming in 2014.

Beyond Einstein would be delayed indefinitely. These are missions such as Constellation -X and LISA that would attempt to answer questions about the Big Bang, Black Holes and Dark Matter.

The Associated Press has reported that a long list of satellites orbiting Earth are under threat of being delayed, downsized or cancelled. Scientists have warned that decreasing funding for these satellites will jeopardize the capability for forecasting weather and monitoring environmental issues.
The list includes:

Landsat: delay in launch of satellite to replace and upgrade Landsat 7, launched in 1999.

Earth Observing System: If cut, satellites such as Aqua (2002) and Terra (1999) would not be replaced when they fail.

Global Precipitation Measuring Mission: The launch of GPMM has been pushed back to 2012. GPMM will replace and upgrade the Tropical Rainfall Measuring Mission, which was supposed to be decommissioned in 2004.

Deep Space Climate Observatory: cancelled. An Earth observing satellite placed at the L-1 Point to determine cloud and radiation properties of the atmosphere. The spacecraft is already built, but would cost $60-100 million to launch and operate.

National Polar-Orbiting Operational Environmental Satellite System: Under review. Will monitor global environmental conditions, and collect and disseminate data related to weather, atmosphere, oceans and land, and is a cooperative effort between NASA, NOAA, the Department of Defense and the Department of Commerce.

The next round of Congressional hearings on the budget proposal are scheduled for March 30 at the House Appropriation Subcommittee on Science, State Justice and Commerce Hearing.

Written by Nancy Atkinson

Posted on by Nancy Atkinson

Satellites on a Budget – High Altitude Balloons

Balloon photograph taken from 25km. Image credit: Paul Verhage. Click to enlarge.
Paul Verhage has some pictures that you’d swear were taken from space. And they were. But Verhage is not an astronaut, nor does he work for NASA or any company that has satellites orbiting Earth. He is a teacher in the Boise, Idaho school district. His hobby, however, is out of this world.

Verhage is one of about 200 people across the United States who launch and recover what have been called a “poor man’s satellite.” Amateur Radio High Altitude Ballooning (ARHAB) allows individuals to launch functioning satellites to “near space,” at a fraction of the cost of traditional rocket launch vehicles.

Usually, the cost to launch anything into space on regular rockets is quite high, reaching thousands of dollars per pound. Additionally, the waiting period for payloads to be put on a manifest and then launched can be several years.

Verhage says that the total cost for building, launching and recovering these Near Spacecraft is less than $1,000. “Our launch vehicles and fuel are latex weather balloons and helium,” he said.

Plus, once an individual or small group begins designing a Near Spacecraft, it could be ready for launch within six to twelve months.

Verhage has launched about 50 balloons since 1996. Payloads on his Near Spacecraft include mini-weather stations, Geiger counters and cameras.

Near space lies begins between 60,000 and 75,000 feet (~ 18 to 23 km) and continues to 62.5 miles (100km), where space begins.

“At these altitudes, air pressure is only 1% of that at ground level, and air temperatures are approximately -60 degrees F,” he said. “These conditions are closer to the surface of Mars than to the surface of Earth.”

Verhage also said that because of the low air pressure, the air is too thin to refract or scatter sunlight. Therefore, the sky is black rather than blue. So, what is seen at these altitudes is very close to what the shuttle astronauts see from orbit.

Verhage said his highest flight reached an altitude of 114,600 feet (35 km), and his lowest went only 8 feet (2.4 meters) off the ground.

The main parts of a Near Spacecraft are flight computers, an airframe, and a recovery system. All these components are reusable for multiple flights. “Think of building this Near Spacecraft as building your own reusable Space Shuttle,” said Verhage.

The avionics operates experiments, collects data, and determines the status of the spacecraft, and Verhage makes his own flight computers. The airframe is usually the most inexpensive part of the spacecraft and can be made from materials such as Styrofoam and Ripstop Nylon, put together with hot glue.

The recovery system consists of a GPS, a radio receiver such as a ham radio, and a laptop with GPS software. Additionally, and probably most important is the Chase Crew. “It’s like a road rally,” says Verhage, “but no one in the Chase Crew knows quite for sure where they are going to end up!”

The process of launching a Near Spacecraft involves getting the capsule ready, filling the balloon with helium and releasing it. Ascent rates for the balloons vary for each flight but are typically between 1000 and 1200 feet per minute, with the flights taking 2-3 hours to reach apogee. A filled balloon is about 7 feet tall and 6 feet wide. They expand in size as the balloon ascends, and at maximum altitude can be over 20 feet wide.

The flight ends when the balloon bursts from the reduced atmospheric pressure. To ensure a good landing, a parachute is pre-deployed before launch. A Near Spacecraft will free fall, with speeds of over 6,000 feet per minute until about 50,000 feet in altitude, where the air is dense enough to slow the capsule.

The GPS receiver that Verhage uses signals its position every 60 seconds, so after the spacecraft lands, Verhage and his team usually know where the spacecraft is, but recovering it is mostly a matter of being able to get to where it lies. Verhage has lost only one capsule. The batteries died during the flight, so the GPS wasn’t functioning. Another capsule was recovered 815 days after launch, found by the Air National Guard near a bombing range.

Some balloons are recovered only 10 miles from the launch site, while others have traveled over 150 miles away.

“Some of the recoveries are easy,” said Verhage. “In one flight, one of my chase crew, Dan Miller, caught the balloon as it landed. But some recoveries in Idaho are tough. We’ve spent hours climbing a mountain in some cases.”

Other experiments that Verhage has flown include a Visible Light Photometer, Medium Bandwidth Photometers, an Infrared Radiometer, a Glider Drop, Insect Survival, and Bacteria Exposure.

One of Verhage’s most interesting experiments involved using a Geiger counter to measure cosmic radiation. On the ground, a Geiger counter detects about 4 cosmic rays a minute. At 62,000 the count goes to 800 counts per minute, but Verhage discovered that above that altitude the count does down. “I learned about primary cosmic rays from that discovery,” he said.

Flying the experiments are a great experience, Verhage said, but launching a camera and getting pictures from Near Space provides an irreplaceable “wow” factor. “To have an image of the Earth showing its curvature is pretty amazing,” Verhage said.

“For cameras,” he continued, “the dumber they are the better. Too many of the newer cameras have a power save feature, so they shut off when they’re not used in so many minutes. When they turn off at 50,000 feet, there’s nothing I can do to turn them back on.”

While digital cameras are easy to interface with the flight computer, Verhage said, they require some inventive wiring too keep the camera from shutting off. He said that so far, his best photos have come from film cameras.

Verhage is writing an e-book that details how to build, launch and recover a Near Spacecraft, and the first 8 chapters are available free, online. The e-book will have 15 chapters when finished, totaling about 800 pages in length.
Parallax, the company that manufactures a microcontroller is sponsoring the e-book’s publication.

Verhage teaches electronics at the Dehryl A. Dennis Professional Technical Center in Boise. He writes a bimonthly column about his adventures with ARHAB for Nuts and Volts magazine, and also shares his enthusiasm for space exploration through the NASA/JPL Solar System Ambassador program.

Verhage said his hobby incorporates everything he is interested in: GPS, microcontrollers and space exploration, and he encourages anyone to experience the thrill of sending a spacecraft to Near Space.

By Nancy Atkinson

Posted on by Nancy Atkinson

Bringing Stardust Home

Stardust’s sample return capsule, safely back on Earth. Image credit: NASA/JPL. Click to enlarge.
NASA’s Stardust spacecraft is now back home, having traveled 4.6 billion kilometers (3 billion miles) and successfully completed its mission in space. On January 15, Stardust’s Sample Return Capsule (SRC) landed safely in the Utah desert, containing samples of a comet’s coma and interstellar dust particles. Stardust was launched in 1999, and in January 2004, the spacecraft performed a risky and historic flyby of Comet Wild 2 to capture the samples and take pictures of the comet’s nucleus.

The trickiest part of the mission, however, may have been guiding the spacecraft back home. The Stardust Navigation Team at NASA’s Jet Propulsion Laboratory in California has been working around the clock for the past few weeks, preparing to bring Stardust’s SRC back through Earth’s atmosphere to land in the US Air Force’s Utah Test and Training Range, southwest of Salt Lake City.

For a successful re-entry and landing, the Navigation team had to target the capsule’s entry to a specific point in the Earth’s atmosphere to within eight 100ths of a degree. One mission manager compared that feat to hitting the eye of a sewing needle from across the room.

Throughout the mission the Stardust scientists have heralded the performance of this desk-sized spacecraft. But members of the Navigation Team have maintained that Stardust’s design provided unprecedented navigation challenges during its entire 7- year mission, culminating with the Earth return.

“Navigating this spacecraft has always been extremely difficult because the attitude control thrusters are all mounted on the same side of the spacecraft,” said Neil Mottinger, a member of the Navigation and Entry, Descent and Landing teams.

The thrusters provide gentle pushes that allow a spacecraft to maintain the correct position while in flight. Normally, most spacecraft have their thrusters placed equally around all sides, but Stardust’s thrusters were positioned so the plume of the thrusters wouldn’t contaminate the particle collector.

“This ‘unbalanced’ thruster design causes a velocity change every time the spacecraft needed to control its attitude, which can occur hundreds of times a day,” said Christopher Potts, the Technical Supervisor of the Flight Path Control Group. “Each thruster pulse is extremely small, but the large number adds up to a significant effect on the trajectory.”

Consequently, the Navigation team needed to closely monitor the daily activity of the spacecraft. “It’s a little like trying to catch a knuckleball,” said Potts, “as the spacecraft trajectory changed noticeably as it reacted to its local space environment.”

Mottinger said that in some aspects, the spacecraft was almost like a bucking bronco. “It was impossible to predict when the thrusters would fire during normal spacecraft operations,” he said, “let alone the times when it would go into a safe mode, firing the thrusters quite frequently to obtaining a ‘safe’ attitude, awaiting further instructions from Earth.”

Both Mottinger and Potts said that in the past few weeks, the Navigation team has gone through tests, training and several full rehearsals for the spacecraft’s return. “We spent a large amount of time postulating what could go wrong,” Potts said, “and making sure there was an appropriate response to correct the problem.”

But with the Navigation Team’s diligent guidance, the SRC landed perfectly, much to the delight and relief of everyone involved with Stardust. Stardust Project Manager Thomas Duxbury said at a press conference following the landing, “This thing went like clockwork. We released this capsule from our spacecraft and it hit the atmosphere exactly on time.”

Mottinger said the hard work the team put in was definitely worth the rewards. “This team has to be exhausted,” he said. “It’s been a real challenge to predict where the spacecraft was headed and fine-tune the entry. I’m in awe of everyone on the Navigation Team who made all this happen.”

Stardust’s SRC will be brought to a clean room at the Johnson Space Center in Houston to be opened. Scientists from around the world will be able to study the thousands of particles of cometary and interstellar dust, many smaller than the width of a human hair. The particles were collected from the coma or “tail,” a cloud of gas and dust that surrounds a comet.

Comets are intriguing bodies, formed in the outer regions of the solar system. Scientists consider comets to be the best samples available of the original building blocks of our solar system, and that the particles Stardust returned should be able to tell us about the conditions of the early solar system.

To determine the makeup of the collected particles, scientists will cut the samples into even smaller pieces and investigate them with powerful microscopes. Stardust scientists are recruiting volunteers to search for the interstellar dust particles using virtual microscopes.

The collector is about the size and shape of a tennis racquet, and is made of a unique substance called Aerogel. Aerogel is made of silicon, but is 99.8% air, so it is the least dense man-made substance. It feels like an extremely light, very fine, dry sponge, and it has the ability to capture fast moving dust. It’s very strong, and easily survived the capsule’s landing on solid ground.

Mottinger and Potts both look forward to seeing the results that the study of Stardust’s samples will bring.

“The entire Navigation team realized we were responsible for delivering a ‘priceless’ cargo of pristine cometary material samples from a comet’s coma,” said Potts. “These samples represent a glimpse back in time at the early formation of the solar system. There’s little doubt that new science discoveries will be made which will influence the direction of future space exploration.”

Written by Nancy Atkinson

Posted on by Nancy Atkinson

Leading the Way Back to the Moon

Computer illustration of the CEV in orbit around the Moon. Image credit: NASA. Click to enlarge.
Jeff Hanley was only 8 years old on July 20, 1969 when Apollo 11 landed on the moon, but he can recall every detail of that day and all the specifics of that historic mission. Each of the Apollo missions to the moon made such a big impact on Hanley that space exploration became his life’s passion, ultimately becoming his profession. Now, Hanley has been appointed to lead NASA’s new program to return astronauts to the moon and prepare to send human expeditions to Mars.

Hanley started working at NASA while he was still in college and eventually became a flight controller in Houston’s Mission Control for 13 years, and then became a flight director in 1996. He oversaw two of the complex missions to refurbish the Hubble Space Telescope and was the lead flight director for the first expedition crew to the International Space Station in 2000. He led the Space Station Flight Director Office for two years before being promoted to chief of flight directors for all space missions in January of 2005.

Hanley has served in his current position as manager for NASA’s new Constellation Program since October 2005. His tenure thus far has been a series of constant meetings, briefings and trips around the country to the various NASA centers. His job is to lead the development of a new spacecraft and launch system, the focal point of NASA’s Vision for Space Exploration.

“We have not developed a new crew launch system from scratch since the space shuttle in the late 1970’s,” Hanley said. “That’s a generational gap we have to overcome, so we’re building a bridge from what we have today to what we want in the future.” The space vehicles that Hanley and his team are designing are combinations of the best elements from both the space shuttle and the Apollo spacecraft with significant improvements that come from advances in technology.

The new Crew Exploration Vehicle (CEV), while reminiscent of the Apollo blunt-body capsule, is three times larger with the capacity to carry four astronauts to the moon. It also has the ability to dock with the International Space Station, and the same crew vehicle will eventually carry astronauts to Mars. The separate lunar module will be able to land anywhere on the moon, including the poles, unlike the Apollo spacecraft that could only land near the equator. Initially, crews will stay up to 7 days on the moon’s surface.

“Apollo’s purpose was to send a man to the moon and return him safely to the earth,” Hanley said. “We go a substantial step beyond that with this architecture in terms of the capacity to deliver large amounts of mass to the moon and that’s really sending the signal that we’re serious about exploration and serious about coming to stay.” Developing a sustained presence on the moon will be the ultimate goal of the lunar missions, to demonstrate that humans can survive for long periods of time on another world.

Computer illustration of the CEV in orbit around the Moon. Image credit: NASA. Click to enlarge.
Instead of launching the entire system at once, the CEV and the lunar module launch separately. “In NASA shorthand we call it the 1.5 launch solution,” Hanley said. “The big heavy booster brings the lunar module and the upper stage to orbit and we’ll follow it with the crew launch vehicle, which launches on a smaller rocket, and the two vehicles will rendezvous and dock. Then we’ll light the Earth departure stage and send it on the way to the moon.”

Hanley continued, “We also want a quantum leap in safety and reliability in our launch systems over anything we have today.” Based on an engineering study, the new launch system will be 10 times safer than the space shuttle. The crew compartment sits on top of the rocket, unlike the space shuttle which is strapped to the rocket’s side. This allows for an escape system that can be used at anytime during launch.

The rockets will combine the reliability and power of solid rocket motors and the space shuttle main engines. The crew launch vehicle will be a single four-segment solid rocket motor with one shuttle main engine, which can lift 25 metric tons. The heavy cargo launch system will consist of two five-segment solid rockets and five shuttle main engines, which can boost 106 metric tons to orbit. A cargo-only mission could bring 21 metric tons of supplies to the moon.

Hanley anticipates the new spacecraft will be ready for its first launch in 2012, but he is challenging his team to have the spacecraft ready as soon as possible. “Our ideal is to make as small a gap as possible between the last shuttle flight [scheduled for 2010] and the first human flight of this system,” he said. “If we have things break our way and utilize good management practices in putting this together, I think we can do it.”

Hanley disagrees with the critics of NASA’s new program who say that returning to the moon is a waste of time and resources when the ultimate human destination is Mars, or perhaps other moons or asteroids. “That would be like the first explorers trying to circumnavigate the earth the first time they set out on the ocean,” he said. “That seems a little na?ve to me. The moon is three or four days away with the current rockets we have. Mars is months away. Once you light off the engines on the Mars transfer vehicle, there’s no turning back. You must have incredibly reliable systems to commit to those kinds of journeys.”

Hanley feels the only way to build up robustness and reliability of a spacecraft is through repeated use over time. “You’ve designed them, built them, and flown them over a period of time such that you’ve weeded out the ‘unknown unknowns,’ as we call them,” he said. “The moon gives us a natural platform to learn from when we get to the point when there’s no turning back from going to Mars.”

In addition, Hanley says, the exploration of other planets will only be successful if we learn to live off the land. “If you look in general at the history of exploration,” he said, “it wouldn’t have been possible without being able to live off the land. We have to learn how to use the available assets, like lunar soil and ice and convert that into rocket fuel and air, cultivating a way station, if you will, from which to test out systems for future exploration.”

Hanley believes that the successful international cooperation that has been forged through the International Space Station program should continue and expand through returning to the moon. “One of the unsung successes of the ISS program is the strong international team that has been cultivated,” he said. “The partnership has endured strains and come through them in great shape. The kinds of relationships and understandings we have today are a great basis on which to build more relationships for exploration.”

“Really,” he continued, “we have no choice but to partner with others to create a really robust program. NASA’s budget in the timeframe we are talking about just won’t be big enough to do all the things that possibly could be done, such as building habitats, rovers, and scientific stations. So there’s a huge opportunity for partners to come in and add value, robustness and capabilities.” Hanley said there have already been discussions at high levels with other space agencies on these matters.

The ISS has also been criticized as wasting time and resources, but Hanley feels everything that has been learned through the ISS program is invaluable. “What we eventually want to do at Mars,” he said, “is build an outpost off the planet. The ISS already is an outpost off the planet. We’ve learned an incredible amount in creating it, sustaining it, and it will, by its very nature, inform us of what the best approaches will be to take the next step.”

“Station is helping us to expand our horizons,” Hanley continued. “We’re learning through the engineering of our systems and cultivating our capabilities at that outpost, so we’re learning about how to rely less and less on supplies from the planet. We’re building heritage. And as soon as we learn the lessons we need to learn on the moon, we will be setting our sights on Mars and I don’t think that will be very long into the future.”

Written by Nancy Atkinson

Posted on by Nancy Atkinson

Book Review: Roving Mars

Somewhere in the midst of exhaustive preparation, astounding scientific discoveries, and a constantly shifting schedule in order to stay on Mars’ time, Steve Squyres, the ebullient scientific leader of the Mars Exploration Rover (MER) program, found time to write an intriguing, behind-the-scenes book about his adventures with NASA’s two endearing rovers, Spirit and Opportunity.

Roving Mars: Spirit, Opportunity, and the Exploration of the Red Planet is a highly readable, personal account of the perseverance and sacrifices it takes to fly a NASA planetary mission. Squyres writes with clarity, eloquence and passion, sharing the gamut of emotions he has experienced in heading up a project of this magnitude.

Roving Mars is divided into three sections, with the first two parts providing an in-depth overview of the MER project from its initial formation in the imaginations of Squyres and his colleagues, through the various designs and configurations that the project endured, to the actual development, testing and launch of the two rovers. With the project plagued initially by politics and bad luck, and then with technical problems with the parachute, airbags and essential scientific equipment, Squyres reveals that MER ran the risk of being canceled almost right until launch. The author tells the stories of the scientific team and the engineers at the Jet Propulsion Laboratory whose tireless dedication and cooperation have made the mission possible. “It’s a strange, heady mix,” writes Squyres, “with NASA-style cool under laid by get-it-done passion, and sometimes, a whiff of desperation.”

Part 3, entitled “Flight” is a real-time diary of events after the rovers launched that follows Spirit and Opportunity into their current explorations on Mars. Squyres’ detailed and vivid descriptions allow the reader to re-live the excitement and drama of events such as the landings of the two rovers and Spirit’s almost fatal computer failure, and provide an inside look at what occurred in mission control, and in Squyres’ mind, in those crucial moments.

With the rovers still going strong after more than a year and a half on Mars, Squyres includes his hopes for the rovers’ future as well as the future of human space exploration. “Roving Mars” includes 32 pages of color photos and illustrations. It is an intriguing and comprehensive account of the mission that has captivated the imaginations of millions.

Read more reviews, or purchase a copy online from Amazon.com.

Review by Nancy Atkinson.

Posted on by Nancy Atkinson

New Horizons Prepares to Zoom to Pluto

Artist impression of the New Horizons spacecraft sweeping past Pluto. Image credit: JHUAPL/SwRI. Click to enlarge.

If all goes well, the first mission to the farthest known planet in our Solar System will launch in early 2006, and give us our first detailed views of Pluto, its moon Charon, and the Kuiper Belt Region, while completing NASA’s reconnaissance of all the planets in our Solar System.

“We’re going to a planet that we’ve never been to before,” said Dr. Alan Stern, Principal Investigator for the New Horizons mission to Pluto. “This is like something out of a NASA storybook, like in the 60’s and 70’s with all the new missions that were happening then. But this is exploration for a new century; it’s something bold and different. Being the first mission to the last planet really ‘revs’ me. There’s something special about going to a new frontier, about

Pluto is so far away (5 billion km or 3.1 billion miles when New Horizons reaches it) that no telescope, not even the Hubble Space Telescope, has been able to provide a good image of the planet, and so Pluto is a real mystery world. The existence of Pluto has only been known for 75 years, and the debate continues about its classification as a planet, although most planetary scientists classify it in the new class of planets called Ice Dwarfs. Pluto is a large, ice-rock world, born in the Kuiper Belt area of our solar system. Its moon, Charon, is large enough that some astronomers refer to the two as a binary planet. Pluto undergoes seasonal change and has an elongated and enormous 248-year orbit which causes the planet’s atmosphere to cyclically dissipate and freeze out, but later be replenished when the planet returns closer to the sun.

New Horizons will provide the first close-up look at Pluto and the surrounding region. The grand piano-sized spacecraft will map and analyze the surface of Pluto and Charon, study Pluto’s escaping atmosphere, look for an atmosphere around Charon, and perform similar explorations of one or more Kuiper Belt Objects.

The spacecraft, built at the Johns Hopkins Applied Physics Laboratory, is currently being flight tested at the Goddard Space Flight Center. Dr. Stern has been planning a mission to Pluto for quite some time, surviving through the various on-again, off-again potential missions to the outer solar system.

“I’m feeling very good about the mission,” he said in an interview from his office at the Southwest Research Institute in Boulder, Colorado. “I’ve been working on this project for about 15 years, and the first 10 years we couldn’t even get it out of the starting blocks. Now we’ve not only managed to get it funded, but we have built it and we are really looking forward to flying the mission soon if all continues to go well.”

Of the hurdles remaining to be cleared before launch, one looms rather large. New Horizons’ systems are powered by a Radioisotope Thermoelectric Generator (RTG), where heat released from the decay of radioactive materials is converted into energy. This type of power system is essential for a mission going far from the Sun like New Horizons where solar power is not an option, but it has to be approved by both NASA and the White House. The 45-day public comment period ended in April 2005, so the project now awaits final, official approval. Meanwhile, the New Horizons mission teams prepare for launch.

“We still have a lot of work in front of us,” Stern said. “All this summer we’re testing and checking out the spacecraft and the components, getting all the bugs out, and making sure its launch ready, and flight ready. That will take us through September and in October we hope to bring the spacecraft to the Cape.”

The month-long launch window for New Horizons opens on January 11, 2006.

New Horizons will be the fastest spacecraft ever launched. The launch vehicle combines an Atlas V first stage, a Centaur second stage, and a STAR 48B solid rocket third stage.

“We built the smallest spacecraft we could get away with that has all the things it needs: power, communication, computers, science equipment and redundancy of all systems, and put it on the biggest possible launch vehicle,” said Stern. “That combination is ferocious in terms of the speed we reach in deep space.”

At best speed, the spacecraft will be traveling at 50 km/second (36 miles/second), or the equivalent of Mach 85.

Stern compared the Atlas rocket to other launch vehicles. “The Saturn V took the Apollo astronauts to the moon in 3 days,” he said. “Our rocket will take New Horizons past the moon in 9 hours. It took Cassini 3 years to get to Jupiter, but New Horizons will pass Jupiter in just 13 months.”

Still, it will take 9 years and 5 months to cross our huge Solar System. A gravity assist from Jupiter is essential in maintaining the 2015 arrival date. Not being able to get off the ground early in the launch window would have big consequences later on.

“We launch in January of 2006 and arrive at Pluto in July of 2015, best case scenario,” said Stern. “If we don’t launch early in the launch window, the arrival date slips because Jupiter won’t be in as good a position to give us a good gravity assist.”

New Horizons has 18 days to launch in January 2006 to attain a 2015 arrival. After that, Jupiter’s position moves so that for every 4 or 5 days delay in launch means arriving at Pluto year later. By February 14 the window closes for a 2020 arrival. New Horizons can try to launch again in early 2007, but then the best case arrival year is 2019.

New Horizons will be carrying seven science instruments:

  • Ralph: The main imager with both visible and infrared capabilities that will provide color, composition and thermal maps of Pluto, Charon, and Kuiper Belt Objects.
  • Alice: An ultraviolet spectrometer capable of analyzing Pluto’s atmospheric structure and composition.
  • REX: The Radio Science Experiment that measures atmospheric composition and surface temperature with a passive radiometer. REX also measures the masses of objects New Horizons flies by.
  • LORRI: The Long Range Reconnaissance Imager has a telescopic camera that will map Pluto?s far side and provide geologic data.
  • PEPSSI: The Pluto Energetic Particle Spectrometer Science Investigation that will measure the composition and density of the ions escaping from Pluto’s atmosphere.
  • SWAP: Solar Wind Around Pluto, which will measure the escape rate of Pluto?s atmosphere and determine how the solar wind affects Pluto.
  • SDC: The Student Dust Counter will measure the amount of space dust the spacecraft encounters on the voyage. This instrument was designed and will be operated by students at the University of Colorado in Boulder.

Stern says the first part of the flight will keep the mission teams busy, as they need to check out the entire spacecraft, and execute the Jupiter fly-by at 13 months.

“The middle years will be long and probably — and hopefully — pretty boring,” he said, but will include yearly spacecraft and instrument checkouts, trajectory corrections, instrument calibrations and rehearsals the main mission. During the last three years of the interplanetary cruise mission teams will be writing, testing and uploading the highly detailed command script for the Pluto/Charon encounter, and the mission begins in earnest approximately a year before the spacecraft arrives at Pluto, as it begins to photograph the region.

A mission to Pluto has been a long time coming, and is popular with a wide variety of people. Children seem to have an affinity for the planet with the cartoon character name, while the National Academy of Sciences ranked a mission to Pluto as the highest priority for this decade. In 2002, when it looked as though NASA would have to scrap a mission to Pluto for budgetary reasons, the Planetary Society, among others, lobbied strongly to Congress to keep the mission alive.

Stern said the mission’s website received over a million hits the first month it was active, and the hit rate hasn’t diminished. Stern writes a monthly column on the website, http://pluto.jhuapl.edu , where you can learn more details about the mission and sign-up to have your name sent to Pluto along with the spacecraft.

While Stern is understandably excited about this mission, he says that any chance to explore is a great opportunity.

“Exploration always opens our eyes,” he said. “No one expected to find river valleys on Mars, or a volcano on Io, or rivers on Titan. What do I think we’ll find at Pluto-Charon? I think we’ll find something wonderful, and we expect to be surprised.”

Posted on by Nancy Atkinson

Has Spirit Found Bedrock in Columbia Hills?

In December of 2004, the mission scientists for the Mars Exploration Rover Spirit spied a ridge near the top of Husband Hill, one of the seven Columbia Hills located near the middle of Mars? Gusev Crater. Steve Squyres, Principal Scientific Investigator for the MER Mission, started calling the ridge ?Larry?s Lookout? and the mission team decided to send Spirit to that ridge to determine what it was and use it as a ?perch? to take a panorama of the valley that it overlooked. They knew it would be a challenge given the sand, steep slope, and rocks in the area, but the scientists are now discovering that the arduous climb was well worth it. According to one geologist, what Spirit is finding at Larry?s Lookout could turn out to be one of the highlights of the MER mission.

The ?Larry? of Larry?s Lookout is Dr. Larry Crumpler; field geologist, volcanologist, and Research Curator at the New Mexico Museum of Natural History and Science in Albuquerque, New Mexico. He is also a mission scientist for MER.

Spirit had originally approached and climbed Larry?s Lookout from the rear, and from that perspective the Lookout appeared to be just a knob on the hill.

But then the rover moved around to the side of Larry?s Lookout, and took a picture that caught the immediate attention of Squyres and other mission scientists. The image looks north along the ridge of the Columbia Hills with Spirit sitting on Husband Hill, and the camera pointed at Clark Hill. The hills are strewn with rocks, and in the foreground are two tilting rocks. The big outcrop just behind the rocks is Larry?s Lookout.

Dr. Crumpler explained the image and the questions it provoked: ?From this perspective, we can see that the outcrop has a tilted look. The two boulders in front of the outcrop appear to be orientated in the same direction. And in the hill in the distance to the right you can see layers that appear to be oriented at the same angles. And to the left, there are outcrops that are oriented at exactly the same angle. The overall impression is that there is some sort of organized layering or structure to the hills. Our big question is, is it just something draped over top of the hills, like ash fall draped over it like snow, or is it an indication of the internal arrangement of the bedding planes in the hills? Did the hills originally form by bulging up, and were the beds originally horizontal? Or did some sort of weathering occur? Any of those interpretations are interesting because it says something has happened subsequent to the original formation of the rocks and hills themselves.?

Crumpler said that this is one of the most interesting areas that Spirit has yet encountered, and the first indication of extensive bedrock. ?For the first time we have started to feel hopeful that we can make sense of the Columbia Hills,? he said. ?I think it is going to be a highlight of the mission.?

Crumpler says they are seeing evidence of finely bedded materials in the rocks, with very fine laminations that signify bedded, sediment-like materials. ?This all indicates that we?re not just looking at volcanic rocks or old broken up rocks, but there is some sort of organized layering,? he said. ?We?re going to do a full scale campaign to try to understand all of these things.? Although the MER science team still has a plethora of unanswered questions about this area of the Columbia Hills, from the evidence so far, water is likely to be at least part of the final equation.

Spirit is just about to begin studying the rock outcrop informally dubbed ?Methuselah,? just to the left of the rover tracks in the image. ?Spirit is looking at this outcrop that is dipping to the northwest and looks like it is laminated with bedding planes,? said Crumpler. ?It is a foot-high outcrop with an odd angle that indicates structure or a deposition that took place on a slope.?

Over the weekend of April 23-24, Spirit was ordered to take a panoramic image of the outcrop in order to give the scientists an overview of the overall pattern and layout of the area.

Crumpler noted that there is a considerable age difference between the Columbia Hills and the lava plain that Spirit crossed to reach the Hills. He likened the Hills to a sandstone butte surrounded by fresh, young lava flows, similar to the landscape that is found in the United States? Southwest. ?The Hills are much, much older,? Crumpler said. ?You can actually see the contact between the two where the lava flows sort of lapped up on the edges of the Hills. When you cross that boundary you go from the basalts which show only small amounts of weathering and alteration to the rocks on the Columbia Hills that are totally ?grunged-up? and altered, and basically water-soaked at some time in their history.?

?We?re still trying to figure out what?s going on here,? Crumpler added, ?but the outcrop we are looking at is giving us some good clues.?

Crumpler has had extensive experience in field geology, and said he has spent a lot of his time walking across New Mexico?s lava flows, just as Spirit trekked across the lava flow in Gusev Crater. He?s always had an intense interest in the geologic exploration of other planets and has been involved in some of the mapping programs of Mars, Venus and Io. But he says the MER program is the most exciting mission of which he?s been a part.

?Everyday there has been something different that we hadn?t seen the day before, or some new perspective of the terrain, so I always say that ?today? is the most exciting part of the mission.?

?When you?re in the field,? he continued, ?you keep moving because you?re always curious about what you?re going to find at the next outcrop that will tell you more about what you are trying to figure out. But we are very likely to be here (at Larry?s Lookout) for a long time giving this outcrop our full attention.?

So, it appears Larry?s Lookout will be keeping Spirit and the MER scientists busy for awhile, as they try to unravel the mysteries of the Columbia Hills.

Written by Nancy Atkinson