Honeysuckle Tracking Station goes Deep Space

by Hamish Lindsay

We had quite a lot of experience with deep space tracking before joining the Deep Space Network full time as we had often helped the Deep Space Station DSS42 at Tidbinbilla in between the manned space missions and Skylab passes.

After the activity and intense pressure with the Manned Space Flight programs it was like a holiday to join the leisurely (to us) long-term projects of California’s Jet Propulsion Laboratory’s Deep Space Planetary Programs. Human lives were no longer at stake – there was much less hype and media attention if a robot spacecraft was lost in space, and the tracking procedures were much simpler and low key. Well, for a start there were no voice communications or medical data to worry about. The critical tracking times were during planetary encounters, when the data had to be received in real time. If it was lost there was no second chance.

After Skylab was abandoned for the last time Honeysuckle Creek left the MSFN in 1974 and was completely gutted of MSFN equipment, except for the antenna and servos, and replaced with deep space tracking equipment. I was put in charge of the dismantling and shipment of all the MSFN equipment and then responsible for all the station drafting for the new configuration, and of course we all pitched in to install the equipment when it arrived.

Our staff was reduced, all the managerial and administration functions were carried out from Tidbinbilla – we became just part of their shift teams. I took over the Station Director’s office and began working on a Canberra Space Centre for the public. I lost my Technical Support Section and staff of five but now had three desks and phone extensions – one for the Space Centre, one for operations, and the photographic darkroom. I also took on the role of public affairs officer and gave lectures and media interviews.

Honeysuckle Creek became Deep Space Station DSS44, a companion to DSS42 and DSS43 at nearby Tidbinbilla, and embarked on the most exciting era of planetary exploration – a string of first-evers to our planetary neighbours. It continued the golden era of space exploration begun by Mercury, Gemini and Apollo to which I was a privileged participant. My friends at Houston told me they were quite envious of my being a part of the deep space program as there was no way they could participate from Mission Control in Houston.

We would call the operations centre at JPL (Track) in California “Track” and when calling the center would say “Track 44” and they would answer “44 Track.”

THE JET PROPULSION LABORATORY, JPL

Occupying 145 acres (58.7 hectares) beside a sand and boulder strewn dry riverbed at the foot of the rugged San Gabriel Mountains in California, JPL was formed in October 1936 by the Caltech graduate students as a rocket research laboratory. The less esoteric title of Jet Propulsion Laboratory was chosen for the institution. On 3 December 1958 JPL contracted to NASA and shifted from military rocket research to scientific spacecraft development and promptly began a comprehensive planetary exploration program.         

Just before JPL joined NASA it kick started the whole American space program with the Explorer 1 spacecraft on 31 January 1958. Once it had teamed up with NASA, JPL supported the Apollo Program with the Ranger, Surveyor and Lunar Orbiter programs and  initiated the Deep Space Program to explore the planets. JPL beat the Russians to send the world’s first spacecraft to successfully rendezvous with another planet when Mariner 2 reached Venus in December 1962 after a four month journey from Earth.

I visited JPL located in Pasadena, California, in 1990 and was shown over the establishment by Bob Latham, whom I had met on his trips to Australia. It was interesting to see TRACK that I had spoken to over the communication links so many times over the years. TRACK was the operations centre for the JPL tracking network that organised the scheduling and details of the various spacecraft’s tracking periods, issued all the acquisition and handover procedures, and in return soaked up our data from the spacecraft.  

 

DEEP SPACE TRACKING EXPERIENCES AT HONEYSUCKLE CREEK

The USB and Operations Room at Honeysuckle Creek in the Deep Space era. It was a home to me – I spent many hours on shift tracking the trailblazing spacecraft such as Helios circling the sun, Pioneer 12 to Venus, the Mars Viking landers, and the Pioneer and Voyager probes to the outer planets. The Operations Console in the foreground with Kevin Gallegos and Les Hughes, the Servo Console with Allan Vonthetoff on the left, the Exciter and Transmitter controls behind in the middle, and Terry Hearn at the Receivers on the right. At times I was the shift supervisor in charge of the station working from the console in the foreground. Kodacolor 4x5 by Hamish Lindsay. Click image for a larger version.

Like the early days of the manned space flights, it was rudimentry tracking in those  days when we first joined the Deep Space Network. Of course, we didn’t think so at the time – we were up there with the latest technology doing things that had never been done before. One example was capturing the spacecraft’s downlink. We would switch on our transmitter and send a signal out to the spacecraft, sometimes simply acquiring a freewheeling downlink, or sometimes taking over from Goldstone in California, when both stations had to follow strict procedures so as not lose the spacecraft signal. We didn’t know what the rest frequency of the spacecraft transponder would be so we had to tune our uplink signal from the lowest point to the highest point of the spacecraft’s spectrum. In those days we had to turn a knob by hand, carefully counting one and a quarter turns of the knob for each second, reading from a clock using Nixie tube numerical displays.

I remember one morning during a Pioneer 11 track at about 0700, at the end of an all-night shift, I had to turn this knob one and a half turns each  second for 35 minutes, wait for a minute, then turn it back for another 10 minutes – 1,800 turns without falling asleep at the end of a midnight shift!! If I had jerked the knob, or changed the speed too much I could lose the spacecraft, and have to get Track at JPL in Los Angeles to recalculate a new set of figures, and go through the whole acquiring procedure again. I never did lose a spacecraft, I don’t think any of us did. Later Tidbinbilla and our team tried to couple an electric motor to the knob, but it wasn’t very successful; then as electronics developed JPL designed a very sophisticated box called a POCA which did the whole acquisition procedure electronically to accuracies of millionths of a second. It wouldn’t twitch, get tired, or fall asleep, but could develop faults, and in its early days we could dial in the wrong figures.

Me at the Transmitter controls, turning the tuning knob to capture the spacecraft’s transponder. The downlink from the spacecraft was fed from the antenna to the receivers to the right of me.  Once It took four hours for my tuning to get to Voyager spacecraft at Saturn and back to the receivers. By 2003 it was taking over twenty four hours at the speed of light! In those days it was manually tuned (it is automatic now) and once I had to turn it carefully for 35 minutes, turning at one and a quarter turns a second watching the clock right in front of my eyes, wait one minute, then tune back for ten minutes to what we called Tracksyn Frequency. And that at the end of a midnight shift. Click image for a larger version.

One morning we were driving to work, and as we came around the hill I saw the antenna was still down on the coll tower. They were supposed to be well into the day’s track. My first thought was something’s seriously wrong with the equipment. I went straight to the USB ops area and asked Martin Geasley, the shift supervisor, what was wrong.

            “We can’t find the spacecaft. We’ve double checked all the figures, tried everything. Track can’t come up with any answer. ”

            “Did you add or subtract the doppler?” I asked.

            “We added it, same as we always do,” he replied.

            “Well, you should have subtracted it, yesterday it reversed,”

I felt confident this was the problem. They subtracted the doppler and promptly locked onto the spacecraft. Which just goes to show how such a simple thing as a plus or minus sign can make the difference between success or failure.



THE VIKING PROJECT

Mars was a great focus for the Americans and Russians during the 1960’s. Many believed there could be life on Mars until our spacecraft arrived. There seemed to be a lot of similarities between our Earth and Mars – apart from visible channels that could be canals, it spins at 24º off the orbital plane (called obliquity); it rotates once every 24 hours 27 minutes; winter ice caps show a rhythm of seasonal changes; and it has dust storms which show there is an atmosphere. However by 1960 the observing scientists knew that Mars was dry, although it wasn’t until later they figured out it was frozen carbon, or dry ice, that made the white winter “snow” caps.

It is thought that Mars’ tilt varies from 15° to 35° over millions and millions of years due to slight gravity tidal effects from Jupiter and Saturn. However its rotational period is more stable than Earth’s because the Earth’s larger Moon is slowing our spin rate. In the Devonian Period, 330 million years ago, our days were only 22 hours long.

For years after we arrived in Canberra we used to watch a television program called My Favourite Martian in black and white. The first attempt to communicate with Mars goes back to 1820 when the distinguished astronomer and mathematician Karl Gauss suggested growing a huge triangle of wheat surrounded by green pine trees, but the scheme fell through when the sensible Russians would not cooperate with those looney Germans. In 1850 French astronomer Charles Cros wanted to focus beams of sunlight from giant mirrors onto Mars and send messages in Morse code. Now how would the Martians read Morse code in French??

However it was in 1877, when Mars was at its closest approach to Earth, that Italian Giovanni Schiaparelli focussed his telescope on Mars and began to draw the first map of the surface of Mars. Peering into the telescope’s eyepiece he could see large blurred dark areas connected by appeared to be a network of dark, narrow lines. “Canali,” he gasped. When this was translated into English as canals and not the more literal channels, Earthlings were convinced – there must be Martians. Then in 1894 the American astronomer Percival Lowell studied these features and he was sure he could see these ‘canals’ criss-srossing the whole surface of Mars, and wrote, “On Mars we see the products of an intelligence. There is a network of irrigation... certainly we see hints of beings in advance of us...”

Despite the results of spectroscope observations indicating a whisper thin atmosphere of carbon dioxide, and the derision of Lowell’s colleagues, countless stories were written about the Martians, among them H.G.Wells’ shocker War of the Worlds, first published in 1897. Actor Orson Welles had read the story as a youngster and was intrigued with it all his life. He was running a successful radio program in New York called the Mercury Theatre and for Halloween on Sunday October 30 1938 decided to broadcast an adaption by Howard Koch.

Koch remembers, “After listening to the broadcast in my apartment, I went to sleep blissfully unaware of what was happening outside. The next morning when I walked down to the barber I was aware of an air of excitement among the passers-by. When I asked the barber he broke into a grin and said, ‘Haven’t you heard?’ and held up the morning newspaper with the headlines NATION IN PANIC FROM MARTIAN BROADCAST.”

Welles had made the broadcast sound as though it was a news item, and began with a reference to Professor Farrell of the Mount Jennings Observatory observing several gas explosions occurring at regular intervals on the planet Mars. Then he said, “the spectroscope indicates the gas to be hydrogen and moving towards Earth at a tremendous velocity.”

Next a series of flaming objects were reported to have fallen on village of Grovers Mill in New Jersey, and reporters from the site describe some cylindrical objects buried in the ground. While they are watching the cylinders something like a grey snake with tentacles emerged and the horrified reporters witness a sudden jet of flame and several of the assembled crowd are reduced to grisly corpses.

Welles now announces, “Ladies and Gentlemen. I have a grave announcement to make. Incredible as it may seem, both the observations of science and the evidence of our eyes leads to the inescapable assumption that those strange beings who landed in the Jersey farmlands tonight are the vanguard of an invading arm from the planet Mars... the monsters are now in control of the middle section of New Jersey and have effectively cut the state through the centre. Communication lines are down from Pennsylvania to the Atlantic Ocean. Railroad tracks are torn and services from New York to Philadelphia discontinued. Highways to the north, south and west are clogged with frantic human traffic...”

1,200,000 of the estimated 6,000,000 listeners took the broadcast literally and reacted accordingly. Several million more who had not heard the broadcast were caught up in the mass hysteria. The next day the newspapers were choked with wild stories of hysterical reactions to the broadcast.

Households were disrupted; many fled homes to escape the gas raids from Mars; church services were abandoned; thousands called the police, newspapers and radio stations all over the country seeking protective measures from the gas; weeping and hysterical women swamped the switchboard of the Journal for details of the massacre; and electricity companies received scores of phone calls to turn off the electricity supply so the cities would be safe from the enemy. One man returned home to find his wife with a bottle of poison in her hand screaming, “I’d rather die this way than like that!”

Welles’ assistant, John Houseman described the scene in the studio, “During the playing of the final theme the phone started to ring in the control room and a shrill voice in the receiver announced itself as the mayor of a big Midwestern city and began screaming for Welles. Choking with fury he reported mobs were in the streets, women and children huddled in churches, violence and looting...

Welles hung up quickly, for we were now off the air, and the studio door burst open. The following hours were a nightmare. The building was suddenly full of people and dark blue uniforms. We were hurried out of the studio, downstairs, to a back office. Here we sat while network employees were busily collecting, destroying, and locking up all scripts and  records of the broadcast. Hours later, instead of arresting us, they led us out of the back way, and we scurried away like hunted animals.”

I can also remember before we landed on Mars everyone was conditioned to blue skies – “Skies are always blue...” and artists happily painted Martian scenes with dark blue skies to be published in learned journals, including the prestigious National Geographic Magazine.

As soon as we landed the Viking spacecraft, the JPL scientists were so anxious to get a picture of the Martian landscape before anything happened, they took a picture, filtered the sky blue and issued the photograph to the waiting world... but when they checked their colour patch later they found that the carbon dioxide sky was really pink and they had to send out a corrected copy of the picture.  A whopping big oops!

The Russians were the first to attempt to land on the Red Planet Mars. Their rocket genius Sergei Korolov was a Mars freak, so it was natural he would try and land a spacecraft at the first opportunity in 1960. Launched in mid October 1960 both rockets blew up, the second on the launch pad killing many people. Then in 1962 they tried again at the next opportunity with Mars I, launched on 1 November 1962. It reached Mars but suddenly without warning signals just stopped as it sailed past the Red Planet at a distance of 193,000 km. Mars II was sent off and arrived safely at Mars and the lander actually reached the surface in February 1974 and for 20 seconds started sending data, the very first from the surface of another planet, but suddenly the signals just ceased. The Russians suspect the poor little spacecraft was overwhelmed by a raging dust storm with winds over 322 kilometres per hour.

The first attempts to reach Mars were fraught with difficulties, the first string of Russian spacecraft vanishing off the radar screens so much so that the JPL Deputy Manager for Mariner 4 jokingly said there must be a Great Galactic Ghoul resident between us, gobbling our spacecraft as they headed for Mars.

NASA’s 261kg Mariner 4 spacecraft experienced an anomaly at the same place, but managed to continue to become the first operational spacecraft to arrive at the red planet on 15 July 1965 after a journey of 230 days. From a height of 10,000 km it snapped 21 television framelets of 40,000 pixels each (which meant with the primitive technology of those days it took 8 hours to transmit one picture!) before slipping behind the planet for its signal to allow analysis of the atmosphere. The pictures were 150 times more detailed than any telescope views from Earth and revealed that the ‘canals’ were really ridge systems and mountain chains. Mariner 4 was Tidbinbilla’s first major mission after being built. In those days. Honeysuckle Creek did not exist, and I was busy with Gemini missions at Carnarvon.

JPL Director Bruce Murray admitted, “When we had the pictures from Mars we couldn’t recognise a thing! We couldn’t even be sure we were looking at Mars. Evidently some dust had collected on the optics, which created instrumental glare. Nothing could be identified. Soberly, we began to invent computer image processing to remove the overriding glare and the planet’s haze.”

The results were disappointing – no signs of advanced technology, no ruined castles, no canals, just masses of Moon-like craters. Multiple library shelves of books on Mars and its people were suddenly complete fiction and no longer relevant.

America followed up with Mariner 6 and 7 flybys in 1969. The 380kg Mariner 6 sped past Mars on July 30 1969, ten days after Armstrong had walked on the Moon, and provided 24 images of Mars. Mariner 7 had a crisis when a rechargeable battery exploded and the signals died. Communications were re-established and after the scientists had reprogrammed the spacecraft to avoid the damaged sections of the spacecraft, a near normal fly-by provided 31 good views of the southern seasonal frost cap of Mars. These Mariners had confirmed there was a weather system on Mars.

In 1971 the much bigger Mariners 8 and 9, weighing 1,020kg, (Mariner 8 failed at launch) were supposed to work as a team to map the whole planet’s surface, but a compromised mission with one spacecraft began when Mariner 9 reached the planet after 167 days and 390 million km to fly past and take 6,786 images of the planet.  Initially the scientists were disgusted to find a huge sandstorm covering the surface, so no pictures. However they were able to implement the new technology of being able to program the spacecraft in real time, so they arranged for the spacecraft to orbit the planet and wait until the storm cleared. It was a long wait (over two months) but then the pictures revealed an unexpectedly exciting terrain – mountains and canyons to knock the socks off our biggest Earthly features. Mount Everest is only half as high as the volcano Olympus Mons, and our impressive 350 km long Grand Canyon is only a scratch alongside the 5,000 km long Valles Marineris, so wide (up to 200 km) in places you can’t see the other side. If you stood on the edge, you would look 7 km down to the bottom! These enormous features are part of the Tharsis Bulge, an enormous region where the planet’s sphere is pushed out of shape by past internal pressures from within. Mariner pictures gave us the first hint of watercourses on Mars. More was to come later with the Viking missions.

Mariner 9 entered Earth’s history books after orbiting the planet for nearly a year when the internal guidance systems failed and the spacecraft began to drift out of alignment with Earth and could no longer be tracked.    

 

WE LAND ON THE SURFACE OF MARS.
HONEYSUCKLE CREEK SUPPORTS THE VIKING LANDERS

THE VIKING SPACECRAFT

To achieve the goals of the Viking Project, a very technically sophisticated craft had to be designed and built. It was a challenge for the age – how do you develop a machine capable of figuring out whether life exists on an alien planet? What sort of life are you looking for – Earth type life, or a completely new type of life based on something other than carbon? As Carl Sagan wrote, “It takes millions of years to evolve a bacterium, and billions to make a grasshopper. With only a little experience we were becoming fairly skilful at it.”

Before the Viking missions we had a visit from Gerry Soffen, the big boss of the science side of Viking Project - even Carl Sagan worked under his direction. Gerry and I got on very well and had some good talks. I asked him what would they do if there was a patch of green just out of reach of the scoop, or they saw some signs of life just yards away. “Nothing,” he said with a shrug, “All we can do is look at it with the camera.”

He was also very surprised to discover our handover procedures – he wasn’t aware of the long delays and the tricky handing the spacecraft signal over from one station to another. As a token of our friendship he gave me a Scientific American magazine and signed it “from a planetary friend.”

Honeysuckle Creek Station Director Station Don Gray (left) and Jerry Soffen from JPL – at Honeysuckle. Photo: Hamish Lindsay. (Editor’s note: On 20th July 2001, at a symposium in Washington celebrating the Viking missions, NASA Administrator Dan Goldin announced that the Viking 2 Lander would be known as the Gerald Soffen Memorial Station. Soffen had died the previous November.)

The Viking Project was begun in 1968 and after seven years of intense planning, research and manufacturing the spacecraft were ready to launch. Each spacecraft was far more complex than any deep space spacecraft ever launched. They contained the equivalent of two power stations, two computer centres, a television studio, a weather station, a seismometer, two chemical laboratories, three incubators for any Martian life, a scoop and backhoe for digging trenches and collecting soil samples.

Viking I was launched from the Kennedy Space Center on 20 August 1975, followed by Viking II on 7 September 1975. Viking I arrived at Mars on 19 June 1976. A July 4 landing on Mars was planned but an unexpected snag delayed the landing. The prime landing area had been chosen from the Mariner 9 images, but when Viking arrived at Mars its superior cameras revealed it was too rough to chance a successful landing. There were large boulders scattered over the whole area, as well as endless cracks and gullies, rifts and holes. The chances of landing a spacecraft safely were highly unlikely.

So, could the Viking cameras find another spot? It wasn’t only a flat area, the scientists wanted somewhere that would have the best chance of finding something interesting geologically, and most important of all, somewhere with the best chance of finding some sort of life, such as a river bed. The scientists would have liked to drop into the bottom of Valles Marineris, where the atmosphere would be heavier and warmer, but the flat ground team won the day.

What if the ‘flat ground’ area turned out to be talcum powder-like dust, and the spacecraft vanished from sight into a sea of powder? Many JPL controllers spent sleepless nights tossing chances around or turning images over, while Viking patiently orbited the red planet.

Viking status reports shrank off the front pages of the newspapers as flight controllers wrestled with seemingly impossible decisions from the limited data available. The second, perhaps backup in case of an accident, spacecraft was still a fortnight away. As the days rolled by, the strain of trying to choose a safe landing area and exhaustion among the flight controllers increased the likelihood of human error in planning and implementing the descent instructions to the spacecraft. Finally a show of hands in the control room settled the new site – Chryse Planitia (Plains of Gold). Unfortunately in the interest of safety the target was a long way from the confluence of the four river beds originally chosen.

At 1247 Pasadena time on 20 July 1976 the flight controllers at JPL sent commands to the Viking spacecraft to separate and the Lander to begin its descent. Shortly after separation the Lander had to flip around and point four small thrusters at exactly the right angle and fire them for 27 minutes to decelerate from orbital velocity and begin a two hour arc down to the surface. At entry interface when the Lander touched the wispy top of the atmosphere the heat shield would have to protect the spacecraft from the 1500°C temperatures and begin to slow the spacecraft down to 900 kph. At an altitude of 7,000 metres the heat shield peeled off and a special parachute burst out and three legs sprouted out of the bottom. At 800 metres three retro rockets fired to stabilise the spacecraft and there was 55 seconds left for the onboard computer to cast off the parachute (so it wouldn’t land on top of the spacecraft) and prepare for a landing. The landing radar switched on to detect big rocks and select a smooth site.

The mission controllers held their breath as they hung onto the signals coming from their robot as it deployed and aligned the dish antenna, poked out the meteorology boom, and sent a safe landing signal back to base.

The leader of the Viking team, Thomas Mutch, described the supreme moment of the project – this was the big test. “It is 5 am. The final descent begins. Conversation stops – an overwhelming silence. We listen to the Flight Controllers as they call out each event...

Then at 5:11am Flight Controller Richard Bender yelled out, “Touchdown! We have touch down!” and the control room erupted with joyous and excited mission controllers cheering and shaking hands.

Eight years of hard work suddenly realised.

They were watching events that happened 19 minutes ago – the time it takes a signal to travel the distance between Earth and Mars at the speed of light, and why all the instructions have to be loaded into the Lander’s computer ahead of time. Reminded of the Russian experience when their Mars III probe failed after only 20 seconds on the surface, the mission controllers had programmed the cameras to grab a contingency picture as soon as possible. Within the hour strip by steady strip of the first black and white image of one of the footpads was scanned onto the monitor.

Then that dramatic moment of the first picture. Mutch again, “At 5:54 am I study the black screen, waiting for that narrow strip that will signal the first few lines of the first picture. And it appears. A sliver of electronic magic. Areas of brightness and darkness. The picture begins to fill the screen. Rocks and sand are visible – and finally at the far right one of the spacecraft footpads. Time and again I repeat, ‘Its incredible.’ An explorer would understand. We have stood on the surface of Mars.”

Viking 1 was safely down, if tilted a few degrees due to a footpad sitting on a small rock, while another was buried in a patch of soft sand. Anxious controllers waited for any movement from the spacecraft, but it remained steady and began to send a steady stream of pictures and data back to Earth.

“Gee, we were lucky,” breathed Gentry Lee when one of the pictures showed a large boulder only ten metres away. Nicknamed Big Joe, the two metre boulder would have destroyed the spacecraft if it had landed on top of it. 

The second Viking spacecraft entered orbit on August 7 1976 and began scanning the terrain below, looking for a suitable landing area. The chosen spot, Cydonia, turned out to have a new phenomena; ‘inside out’ craters, sticking up from the surface instead of a hole in the ground, probably caused by millions of years of winds tearing away the loose topsoil and leaving the hardened crater floors. Cydonia was struck off the list of suitable landing sites.

The next choice was Utopia Planitia, and on 3 September 1976 the Viking 2 Lander dropped onto its flat plain almost exactly half way around the planet from the Viking 1 landing place. It was another successful touchdown, but the scene revealed by the cameras was even more desolate and littered with endless cinder-like rocks than Chryse. The scoopful of soil turned out to be similar to Viking 1’s, with no trace of any organic compounds. Carl Sagan was very disappointed that the two sites, so far apart on opposite sides of the planet proved so similar.

The geologists found that the surface of Mars was made of oxides of iron and titanium, silicon dioxide, aluminium, magnesium, calcium, and sulphur. It is the iron oxides that mainly give the planet its red colouring.

Now JPL had four operational spacecraft independently studying Mars, and Track was controlling a small fleet of vehicles at the same time, the two Orbiters relaying the Landers’ signals. We were even getting regular weather reports from the Mars surface.

On the morning of 1 July 1976, the brand new Air and Space Museum of the Smithsonian Institution in Washington was opened by President Gerald Ford when a ribbon was cut by a signal sent from the Viking Lander from the surface of Mars.

Planned for a minimum 90 day full scale mission the Viking spacecraft excelled with their duty and the first spacecraft to fail was the Viking 2 Orbiter, which ran out of gas on 25 July 1978, followed by Viking 1 Orbiter on 7 August 1980. Viking Lander 2 failed on 11 April 1980 and the last Viking contact with Mars was when Lander 1 transmission failed on 11 November 1982. 

The quest for life on Mars is not over, as scientists have found forms of life on Earth which live in a more hostile environment than the surface of Mars. There could be forms of life such as bacteria living in cracks and fissures, or under the surface. Only a thorough search by humans on the surface and analysis back on Earth will really determine a final unambiguous result, although I feel personally it is a forlorn hope.