years 20 ar ound th Odyssey’s future remains unknown, but a lack of advocacy might indicate its end is near. BY NOLA TAYLOR REDD

hen NASA’s While Odyssey is nevertheless Odyssey managing to still carry out its job in spacecraft space, it’s struggling in the political Wblasted off in arena. President Trump’s 2021 bud- 2001, Mars was get request, released in February considered a dry, barren world. 2020, most clearly threatened mis- But over the past two decades, this sions like SOFIA, a telescope that quiet powerhouse of an orbiter has flies on a plane. However, the revealed a wealth of information danger to Odyssey was more subtle: about the Red Planet. During its Trump’s 2021 budget slashes first year around Mars, Odyssey Odyssey’s funding from just under found the first direct evidence $12 million to around $1 million. of subsurface water on This would effectively pull the plug the planet. The orbiter on a working spacecraft, whose pri- also currently holds the mary costs are human maintenance record for the longest and guidance. continuous observa- But “Odyssey is remarkably tions of martian healthy,” says Phil Christensen, the weather, which is principal investigator for Odyssey’s an ongoing study Thermal Emission Imaging System with important (THEMIS) and a geologist at implications for . “It’s just ABOVE: The 2001 Mars future human this crazy workhorse spacecraft that Odyssey space- habitation rarely goes into safe mode.” craft launched April 7, 2001, aboard a of Mars. Boeing Delta II rocket, Twenty years of Two decades of science starting a seven-month wear and tear have undoubtedly Odyssey arrived at Mars on journey to the Red Planet. NASA/KSC taken their toll on the plucky October 24, 2001, with the goal of robotic craft. In fact, a series of investigating the martian environ- RIGHT: The Mars Odyssey logo depicts strong solar flares put one instru- ment. The spacecraft was designed the spacecraft taking ment out of commission in 2003, to map the planet’s chemical and thermal and gamma-ray just a few years after blasting off for mineralogical makeup as a step data with its THEMIS (right) and GRS the Red Planet. And, in 2012, the toward understanding the role (left) instruments. spacecraft lost one of four reaction water played in shaping the envi- NASA/JPL/CORBY WASTE wheels, which are responsible for ronment, both past and present. controlling its orientation (though The orbiter completed its primary the three remaining wheels con- mission in August 2004, then began tinue to function). to take on a series of two-year

20 ASTRONOMY e RED PLANET

Mars Odyssey has spent nearly two decades collecting data while in orbit around the Red Planet, helping researchers produce thermal maps, chart deposits of buried ice, trace the distribution of various elements, and more. NASA/JPL-CALTECH

WWW.ASTRONOMY.COM 21 MARS ODYSSEY AT A GLANCE High-gain antenna

Made of mostly aluminum and titanium, has been orbiting the Red Planet since October 24, 2001. Although a solar storm quickly took down the spacecraft’s MARIE instrument, meant to characterize Mars’ radiation environment, the rest of its instruments remain in good shape. These include a thermal imager (THEMIS), a gamma ray spectrometer (GRS), and a high-gain antenna that helps martian Solar array rovers and landers communicate with . ASTRONOMY: ROEN KELLY

MARIE (inside)

Star cameras Gamma ray sensor head

Neutron High Energy spectrometer THEMIS Neutron Detector (HEND)

Ultra High Frequency (UHF) antenna

mission extensions, each dedicated minerals that are heated by the beneath Mars’ surface, it didn’t to a specific set of objectives. Sun radiate that heat back into stop there; the craft also uncovered “Odyssey has played a pivotal space, allowing THEMIS to chart snowpacks in some of the planet’s role in changing how we think the planet’s mineralogical makeup warmer regions. These snowpacks, about Mars,” says Lori Glaze, at night. GRS, also still active, has potentially remnants from a mar- NASA’s Planetary Science a similar job: mapping chemicals tian ice age, provided some of the Division director. “It has really by monitoring gamma rays pro- first hints that Mars is experienc- changed our perception of a duced when cosmic rays strike the ing ongoing climate change. planet that [we thought] was a martian surface. This technique “There’s a lot of ice on Mars,” dry desert to one that’s a frozen allowed GRS to play a key role in Christensen says, pointing out that desert.” discovering water ice locked just in some places it can lie as deep as 10 inches (25 centimeters) beneath the surface. “That’s going to be “There’s a lot of ice on Mars,” Christensen says, pointing out that extremely important when we send in some places it can lie as deep as 10 inches (25 centimeters) beneath humans to Mars, using that water the surface. “That’s going to be extremely important when ice.” Mining ice could potentially provide the liquid water that we send humans to Mars, using that water ice.” humans need to survive, without having to lug it from Earth. Odyssey carried three main below the ground in 2002. This potential for in situ science instruments to the Red MARIE’s job was characterizing resource utilization — using what Planet: THEMIS, the Gamma Ray the radiation environment of space materials are locally available — Spectrometer (GRS), and the around Mars. However, MARIE is an important factor in selecting Mars Radiation Environment shut down in 2003, after charged future human landing sites on Experiment (MARIE). THEMIS is particles from the Sun bombarded Mars. A 2019 paper published in still active today, working to map the spacecraft, irrevocably damag- Geophysical Research Letters used the distribution of minerals on ing the instrument. data from Odyssey and its sister Mars’ surface by scanning it in Although Odyssey made an craft, the Mars Research Orbiter, visible and infrared light. Martian initial splash by finding signs of ice to look for ice that could easily be

22 ASTRONOMY • DECEMBER 2020 AN ORBIT TO REMEMBER

Mars orbit insertion October 23, 2001 Outer cruise 3 4 Mars

Spacecraft initialization Deploy solar array 2 Mars Odyssey reached and studied the Red Planet by 8 relying on a series of different orbits, Polar orbit including cruise phase, capture, Earth aerobrake, mapping, 7 and polar orbits. The Mapping orbit cruise phase lasted 5 about 200 Earth days Capture orbit 6 and the initial 1 Aerobrake orbit mapping phase lasted about 900 Launch from Earth Earth days, though April 7, 2001 the mission has since Delta II rocket received multiple extensions. ASTRONOMY: ROEN KELLY

dug up by intrepid human explor- variability in weather and climate,” ers. “You wouldn’t need a backhoe says Odyssey’s project scientist, to dig up this ice. You could use a Jeff Plaut, a researcher at JPL. shovel,” the paper’s lead author, “The role of large dust storms is a Sylvain Piqueux of NASA’s Jet focus of this research, and Odyssey Propulsion Laboratory (JPL), said acquired detailed observations of in a press release. “We’re continu- two of these global storms during ing to collect data on buried ice on its mission.” Mars, zeroing in on the best places One of Odyssey’s greatest for astronauts to land.” achievements, however, was its But water isn’t the only impor- comprehensive map of the Red tant consideration when it comes Planet. In 2010, researchers to landing future astronauts on combined some 21,000 THEMIS Mars. Odyssey has also been images to create the most accurate studying the Red Planet’s weather global map of Mars to date. for nearly two continuous decades. According to Plaut, the map is now Over that time, it has homed in the starting point for almost all on global dust storms, water ice geologic studies undertaken on the Odyssey’s THEMIS clouds, and atmospheric proper- Red Planet. “[THEMIS] gave us a instrument scans the surface of Mars in ties, painting a clearer picture of very detailed view of the physical underground stresses near the vol- this artist’s concept. Mars’ changing climate, nature of the surface,” Christensen cano. And while the caves are too By combining some 21,000 THEMIS Christensen says. says. “That’s provided tremendous high up to be much use for poten- images, researchers Odyssey’s extensive dataset insight into the physical properties tial human habitats — or, for that created the most accurate global map also overlaps with weather data that are acting on Mars today.” matter, for hosting microbial life of Mars’ surface to collected by NASA’s Mars Global THEMIS also helped scientists — they spurred the hunt for lower- date. NASA/JPL-CALTECH Surveyor, and other orbiters have find a collection of seven caves on altitude caves and lava tubes. provided complimentary observa- the slope of the volcano Arisa “No other instrument at Mars tions. “This allows us to look at the Mons. These martian grottos could give the thermal information repeatability and the year-to-year likely formed due to natural crucial to this research,” Plaut said

WWW.ASTRONOMY.COM 23 Martian soil greatly enriched with hydrogen, a tracer for water, is shown in a press release after the find. far from finished with its science. out a significant amount of sci- in dark blue in this “This is a great example of the “We have a number of ongoing ence during its lifetime, it has global map created using Odyssey exciting discoveries Odyssey science investigations, primarily also served as valuable support observations of continues to make.” with the THEMIS infrared and for other missions. Odyssey has medium-energy neutrons streaming Although THEMIS has helped visible camera,” Plaut says. Those helped researchers select the land- from Mars’ surface. researchers to make great discover- include observations of the mar- ing sites for the The deep blue areas ies, mapping the martian surface tian atmosphere early in the rover, the InSight lander, and near the polar regions emit fewer isn’t a new job description. On the morning and just after sunset, the Perseverance rover; plus, the neutrons and are other hand, the now-defunct which could provide “unique orbiter provided confirmation that thought to contain up to 50 percent MARIE was the first experiment information on the patterns of Curiosity had pulled off its unique water ice in the top specifically sent to Mars to prepare weather and climate that are not sky crane landing maneuver. And 3 feet (1 m) of soil. for an eventual human presence. available to other orbiters,” he says. in 2010, when the Phoenix Mars Green, yellow, and red regions Unfortunately for future martians, Even now, scientists continue Lander suffered through a chilling correspond to MARIE found that radiation levels to publish studies that depend on martian winter it wasn’t designed progressively smaller amounts of from solar flares and cosmic rays Odyssey’s data, demonstrating its to survive, Odyssey spent several surface hydrogen. are two to three times higher on ongoing value. And as other mis- periods of time listening for hints NASA/JPL/UA/LANL the Red Planet than on Earth. sions arrive at the Red Planet, that the lander had come back to That’s because Earth is protected Odyssey remains in a position to life following the return of spring- by our planet’s hardy magneto- help solve questions that have not time sunlight. sphere and thick atmosphere, yet been asked. Or, as Plaut says: The orbiter also serves as which Mars lacks. That’s not ideal, “New discoveries continue to pro- a communications hub, a role but it is vital environmental infor- vide us with new targets.” that began in 2004 with Spirit, mation to know. Opportunity, and Phoenix, and With its 20-year anniversary on Rovers phone home continues with Curiosity and the horizon, the spacecraft is still While Odyssey has pumped InSight. Plaut says that Odyssey

24 ASTRONOMY • DECEMBER 2020 COSMIC RAY ENVIRONMENT Dose equilavent values (rem/yr)

10 12 14 16 18 20 N

0° 180° 360°

S By measuring gamma rays produced when cosmic rays strike Mars’ surface, Odyssey has allowed scientists to create a global map of Mars that shows the estimated radiation dosages on the planet, a serious concern for future human explorers. For reference, ISS astronauts experience about 20 to 40 rems per year. NASA-JPL/JSC

$218 million — is already done. he says, “and not knowing the “When you buy all the parts for seismic history is a huge knowl- a spacecraft, it’s worth a certain edge gap.” amount,” Christensen says. “When That same thing could happen you assemble it, it’s worth more. on Mars if Odyssey falls by the When you get it tested, now it’s wayside. In addition to its ability really starting to be really worth to perform general science, broadcast a “large majority” of the something. Then you launch and Odyssey also has the only thermal science data collected by Spirit and get it to Mars, and now it’s this infrared imager currently orbiting Opportunity over their seven- and priceless thing.” Mars. And THEMIS’ hundreds of 15-year mission lifetimes, respec- “I think it’s silly to shut it off,” thousands of images have signifi- tively. According to Plaut, InSight says Brian Hynek, a Mars scientist cantly changed our understanding currently uses Odyssey for relaying at the University of Colorado, of the nearby Red Planet. most of its data and almost all its commands. In total, Odyssey com- municates with rovers or landers “When you buy all the parts for a spacecraft, it’s worth a certain amount,” multiple times almost every day, Christensen says. “When you assemble it, it’s worth more. When you get it says Plaut. tested, now it’s really starting to be really worth something. Then you The end of the road? launch and get it to Mars, and now it’s this PRICELESS thing.” Considering Odyssey’s ongoing productivity, it seems strange that Boulder. Hynek isn’t on the “There is no instrument right it would be lacking in political Odyssey team, but he uses the now on any other [martian] space- support. Although government spacecraft’s data. “It’s still craft or anything planned that has bean counters may point to the collecting great data, and it’s a thermal imager,” says Tanya expense of keeping a 20-year-old still working,” he stresses. Hynek Harrison, a planetary scientist who spacecraft afloat, scientists say points to the lunar seismometers studies Mars and has often relied that the costs of maintaining it are placed on the Moon during the on Odyssey observations. “We miniscule compared to the science Apollo missions, which were shut wouldn’t be able to do any of the it returns. After all, the expensive down due to funding cuts. stuff we’re doing with THEMIS if and risky part — building and “Now we’re trying to send peo- we turned off Odyssey.” launching it to Mars at a cost of ple there and build settlements,” One major reason spacecraft

WWW.ASTRONOMY.COM 25 Mars Odyssey, seen in this artist’s concept, has returned hundreds of thousands of images over the past two decades, many taken with its high-resolution THEMIS imaging system. NASA/JPL-CALTECH

Students discovered a lava cave with a skylight by looking through hundreds of TES (Global Surveyor) resolution THEMIS (Odyssey) resolution images taken by Mars Odyssey. After closely studying the site, they were then able to request targeted observations. NASA/JPL-CALTECH/ ARIZONA STATE UNIVERSITY

for it. NASA isn’t requesting an increased budget and no legislator seems particularly disturbed by the loss of the mission. It’s possible that a public groundswell of sup- port could make a change, but the mission’s potential demise hasn’t attracted a lot of attention. If nothing changes with Trump’s proposed budget — and 5.5 miles (9 km) Odyssey’s funding is slashed — mission controllers would likely have no choice but to permanently As illustrated by shut down the craft. However, the these views of exact process for shutting down Verde Valley in Arizona, Odyssey’s are shut down is due to lack of missions and left Odyssey at the Odyssey isn’t publicly available, THEMIS imaging fuel. However, Odyssey has plenty shutdown level. and Freedom of Information Act system achieves higher resolution of fuel left in the tank, enough for The next step is for the Senate requests filed by Astronomy have (328 feet [100 m] per 10 more years, Plaut says. “All to pass its own bill. But people been delayed, due, in part, to the pixel) than the spacecraft systems required for familiar with the budget process COVID-19 pandemic. Still, Thermal Emission operations are in good health.” say that’s unlikely to happen until Odyssey’s end has essentially Spectrometer (TES, Yet the mission remains on the after the 2020 presidential election been planned since launch. 59 feet [18 m] per pixel). THEMIS chopping block. in November — even though the “Whether it’s financial need to can trace minerals new budget is supposed to kick off [shut down], or it reaches its end such as carbonates, silicates, hydroxides, Flipping the switch in October, the start of the 2021 of [its] life, at some point, with a hydrothermal silica, Currently, Odyssey’s future fiscal year. After the passage of the 20-year-old orbiter, you need to sulfates, oxides and remains nebulous, and President Senate’s bill, the Senate and House plan for these things,” Glaze says. phosphates. NASA/JPL-CALTECH/UNIVERSITY Trump’s proposed budget is of Representatives will come “We’ve been planning this for a OF ARIZONA just the first hurdle in a long together to resolve their differences long time.” race ahead. In July, the House before voting on the newly drafted According to that plan, mission of Representatives passed its budget. Finally, after it passes, the controllers would turn off Commerce-Justice-Science president will sign the bill. Odyssey’s science instruments and Funding Bill, which echoed the Right now, Odyssey doesn’t verify its orbit. Finally, they would president’s numbers for NASA’s seem to have anyone advocating tell Odyssey to dump its fuel, and

26 ASTRONOMY • DECEMBER 2020 With the help of Mars Odyssey, especially the sign off. Listless and silent, we’ve ever been to making this a images of Mars, the students were THEMIS instrument, Odyssey would drift around Mars, reality.” But, although that could then eligible to request Odyssey scientists have uncovered ample its orbit decaying over the decades, very well happen, it might force us take a targeted image of their site. evidence that water until it eventually crashes down on to give up on a working mission. “If Odyssey just became a student once flowed on the Red Planet. The the same martian surface that it so And, according to Hynek, “You’re camera, I think it would be worth infrared mosaic at meticulously mapped. going to lose a lot by shutting the money to keep it,” Christensen left shows Mangala [Odyssey] off.” says. “I’m a long way from giving Fossa, an area between two faults The budget circle of life Christensen and others are still up on this mission.” located at the head Odyssey’s budgetary shakedown considering unique ways to save “We’re going to do everything of Mangala Valles. The image at right is part of a broader realignment Odyssey, including potentially we can to try to keep it going,” zooms in on a of NASA’s Mars exploration strat- converting it into a spacecraft for Glaze adds. “We’re putting forth breach in Mangala egy that focuses on bringing back use by students and enthusiasts. every effort to make sure we have Fossa’s northern wall, which was samples from Mars — something There is precedent: In 2010, a class the capability to use the spacecraft most likely carved for which scientists have been of seventh graders in California as long as we can.” by floodwaters released when the advocating for decades. taking part in Arizona State underlying Mangala Returning samples from Mars University’s educational program Nola Taylor Redd is a freelance fault grew wider “is going to change the way we discovered a martian lava tube science journalist who focuses on due to upswelling magma. NASA/JPL- think about Mars again,” Glaze with a skylight. After closely space and astronomy. She is based CALTECH/ARIZONA STATE says. “We are far, far closer than studying more than 200 THEMIS outside of Atlanta. UNIVERSITY

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