1. Expedition 6 Background

Expedition 6 launched from Florida on November 23, 2002, on STS 113, Space Shuttle Endeavour. It was slated to return on STS 114, Space Shuttle Discovery in early February of 2003. Per schedule, Expedition 6 was going to be the shortest mission to date. During the mission, STS 114 launch was slipped into March. On February 1st, 2003, STS 107 Columbia, flying a science mission in an orbit not connected to the Space Station, disintegrated on entry. This delayed STS 114 launch for 21/2 years and caused the Expedition 6 crew to extend their mission to 51/2 months and return via our Soyuz spacecraft on May 3, 2003.

Our Soyuz was TMA-1, the first flight vehicle off the production line in 25 years with a major upgrade to the cockpit. During entry, shortly after spacecraft separation from its propulsion and orbital modules, a small malfunction in a signal processing box that converts computer commands into jet firing signals caused us to loose the reaction control system (it is not known to the author if this malfunction was the result of the cockpit upgrade). This malfunction occurred when we were out of radio contact with mission control. We downmoded to an unguided ballistic entry where we experienced over 8 g loadings and landed about 475 kilometers short of the nominal landing site. Following the initial landing impact, our capsule rolled a few times and ended up on its side about 30 meters from the point of touchdown. The trajectory brought us out of radio range for the parachute phase line-of-sight VHF radios, thus, the ground support team had no idea where we had landed. About two hours postlanding a search airplane flew overhead and we were able to make radio contact. About 3 hours after radio contact, the ground support personnel arrived via helicopter.

Due to these series of events, we as a crew performed a number of operational tasks previously not required by long duration crews. Given our sudden transitions from long term weightlessness, to 8 g’s, to the big thump, to being on our own in Kazakhstan, these tasks were physically taxing and not easy to accomplish. However, by working as a crew in this degraded state, we were able to take care of ourselves and complete basic survival tasks without outside help. We were not quivering sacks of Jell-O. This was due in part to the advancement in physiological countermeasures made on the International Space Station.

2. Mars Landing on Earth

The parallels of our mission to that of one to Mars are striking. First we lived in a weightless environment for 5 1/2 months. Six months is a good canonical number for a one way trip to Mars which could be adjusted either up or down depending on the choice of propulsion technology. Our level of deconditioning due to a long weightless journey was similar to a crew arriving at Mars. We piloted our own spacecraft through a high-g maneuver, similar to what a crew will do at Mars.

Following the entry, our landing sequence involved a combination of parachutes and landing rockets culminating in a hard landing in one of the more remote places on Earth.

For Mars, a combination of parachutes and landing rockets will be one of the more attractive technical options for the landing sequence.

While on our own we performed a number of basic operational tasks not unlike a crew might perform after landing on Mars. We performed spacecraft safing. This involves reading procedures (in Russian), flipping switches, and pushing buttons on the control panel to power down unneeded equipment so that battery life for radio operations can be extended. Since the Soyuz capsule ended on its side, our operations were done from a position of being strapped into a seat fixed on a slanted ceiling. We opened the hatch, unstrapped, and crawled out. In my spacesuit, I weighted 90 kilograms. On Mars at 0.38 of Earth’s gravity, it would require over 240 kilograms to equal the same loading on our bodies. This leaves about 150 kilograms for a required Mars surface suit. Following egress, we deployed the survival gear that was stowed in numerous small bundles throughout the spacecraft. Included were warm woolen cloths, food, water, a medical kit, a portable radio, and a signaling kit that contained a shotgun pistol that can fire flares as well as shotgun cartridges. Setting up a radio beacon was a priority.

We deployed two radio systems. One was a small VHF hand held radio that required assembly with its battery pack (transmitting power was 0.15 watt) and another that used the Soyuz VHF radio system with an external antenna. The antenna resembled a long, self-erecting tent pole and was bolted to a fixture on the hatch ring. There were no rescue aircraft within range. We unpacked food and water but no one was hungry. When the helicopters came near we fired a volley of flares from the shotgun pistol to signal our location. Performing these basic survival tasks was not easy. Moving was provocative. Your vestibular apparatus bitterly complained when there was head movement. Of the three of us, my symptoms were the greatest which is not uncommon for a rookie. Apparently, your body remembers the trials of past space flights making each additional one easier. For my crewmates, walking was labored but was done as needed shortly after landing. I had trouble walking but could crawl. By crawling back and forth between our Soyuz capsule and our mounting pile of survival gear I was able to contribute to our "base camp".

There were no systemic aches or pains associated with movement. We had good muscle strength. We had the lean muscled look of someone coming home from health camp, not the muscle-atrophied bodies from historic long duration space flight. My limbs felt heavy because my brain was not yet compensating for their weight. Like an electronic scale that tares out the weight of the beaker so that only the contents is weighed, your brain normally subtracts the weight of your limbs from the gravity equation so you primarily feel the weight that you hold. Upon returning, the brain had not yet kicked in this compensation which takes about 10 to 15 hours. Slow and deliberate motions were readily made with sufficient motor control to connect electrical wire harnesses, antennas, cycle switches on control panels, and shoot a shotgun pistol. Motor control for operating the spacecraft mechanisms and survival gear was not a problem. However, fast coordinated movement was not possible for me.

We were able to accomplish the necessary operations by working as a team where we each contributed within our current physical ability. Perhaps most important, we were each able to take care of our personal needs; a down crewmember requiring care from a second person would have effectively reduced our crew of three to a crew of one.

This data point helps address questions about whether our countermeasures are working to prepare crews to function for the critical tasks of landing and the initial ground operations following a long weightless journey to Mars. A well-designed mission should have minimal demands on the crew after landing, giving them a few days for adaptation before engaging in significant operational tasks. There could be contingencies, there could be malfunctions, that require immediate response. We demonstrated that our current level of countermeasures is working towards preparing crews for contingency tasks although there is a real need to continue efforts for improvement in human post-landing performance. Improvement in post-landing performance will give the mission extra margin where the crew could intervene in off nominal conditions.

3. Taking Low Earth Orbit Experience to Mars

The purposes of Space Station are many. Some are focused on basic research whose real use is on Earth. Some apply to the hardware and to operational knowledge needed to enable human exploration beyond low earth orbit. Knowledge about human physiology and the countermeasures so that we can make long productive journeys into space is one obvious area. Engineering research where spacecraft technology is advanced for the sake of future robust spacecraft design is another. Operational knowledge such as how to run, maintain, and repair failed hardware in the isolated spacecraft microcosm is essential and an often overlooked benefit from our current earth-orbit program. We have learned time and time again in low earth orbit that there can be serious consequences to seemingly small malfunctions. When the toilet breaks on space station, work comes to a halt and efforts are focused on fixing the toilet. If the toilet becomes un-repairable, either new parts are sent up (the crew reverts to Apollo plastic bag technology until they arrive) or the crew comes home. From the International Space Station the crew can abort to earth when needed in about 1/2 day. On a mission to Mars, a hard failed toilet would lead to slow crew dehydration and eventual death due to the toilet being an integral part of the recycled water supply for a multi-year journey. Gaining hardware and operational knowledge in low earth orbit before we venture away from our home planet on multi-year expeditions is essential for mission success. There are aspects of a Mars mission that are difficult to simulate by low earth orbit analog missions. Mars gravity at 3/8ths Earth’s and the Martian atmospheric pressure-compositions are examples. A lunar outpost is a logical extension that is worth considering.

Perhaps the most difficult aspect to simulate is the human mind-set of a Mars mission. For us in Expedition 6, we knew that helicopters were looking for us. We knew that by the day’s end, or at most, by the next morning a ground team would arrive. On Mars there will be no ground team and this fact irreversibly changes the crew’s psychology. Earth from Mars will be a blue dot in the night sky and will surely give a meaning to the concept of isolation that explorers have not felt on Earth in perhaps 400 years.

While true isolation can no longer be found on Earth, other psychological factors can. The International Space Station has been continuously occupied for ten years. Many common psychological events that humans experience on Earth have also been experienced in orbit. Crews have been gone during every holiday, anniversaries, birthdays, recitals, graduations, weddings, family breakups, stock market crashes, wars, terrorist attacks, voting, jury duty, death in the family, funerals, and taxes. Death of fellow crew members occurred for us when Columbia disintegrated on entry. It did not matter that they were in a separate spacecraft. Grieving for the loss of your friends and the impact on their families transcends into space. This occurrence impacted my mind-set in yet another way; it caused a momentary stutter in the explorer’s mantra, "It can’t happen to Me". After a short time of reflection, I returned to the ever present work of the mission.

4. The Limitations of Empirical Solutions

The life science researchers at NASA have made significant progress towards long duration space flight countermeasures. Exercise prescriptions have been developed that crews follow rigorously. A blend of resistive and cardiovascular exercise along with diet has made good progress towards reducing the negative effects of long duration space flight. Heavy loading of large bone-muscle groups in the form of "weightlifting squats" using a resistive exercise machine with loadings as high as 260 kilograms have significantly reduced bone and muscle degradation. Typically, crews will perform heavy exercise for 2 hours a day. With every returning crew from Space Station, the total number of human data points increases, aiding the statistics between cause and affect.

Our current countermeasures knowledge is based on empirical success. The fundamentals behind this success are not well understood. To reap the maximum benefit, it is important to continue the basic research to understand the nature behind the empirical fix. The obvious shortcomings to an empirically derived solution surface when they are extrapolated beyond the conditions from which they were designed. What would be the result if the mission was traveling to Mars instead of remaining in low earth orbit? Does the radiation environment affect these findings? Empirical knowledge is difficult to extrapolate beyond the conditions under which it was originally developed and permutations to the recipe are best done from a strong basis of fundamental understanding. History can sometimes provide useful analogies to help guide the present and perhaps reflect on the future of space exploration. The link behind oceanic exploration and scurvy serves as an example of empirical solution followed by fundamental understanding. Scurvy1 during the age of oceanic exploration killed hundreds of thousands of sailors and impacted missions, outcomes of sea battles, as well as the populations on the continents whom never ventured from shore. The cure for scurvy was compounded by the fact that scientific methods were themselves in the process of being invented.

In 1747, James Lind, a British naval surgeon, did the first controlled scientific trails on a cure for scurvy and found that the disease could be prevented with lemon water. This empirical discovery was not put into practice on British naval ships (due to the reluctance of accepting this new scientific method) until 1795, ironically one year after Lind's death. After that point, an empirical operational fix for scurvy and crews going on long duration sea voyages was in place. It was not until the fundamental discoveries of vitamins (in 1912 the word vitamin was coined by Casimir Funk), and the isolation of vitamin C in 1932, 165 years after the empirical cure of Lind, that a fundamental understanding behind scurvy occurred. Armed with this fundamental knowledge, improvements in health for the masses of humanity that stayed firmly on the continents were made. The immediate empirical solution aided exploration for the sake of exploration. The fundamental knowledge gave the extensive benefit to the balance of humanity. Time will tell if this story will repeat under the new venue of space exploration.

5. Conclusion

Expedition 6 to the International Space Station was able to accomplish a full pallet of tasks including space station construction, maintenance, and scientific investigations in human physiology. However, a significant aspect of our mission was the serendipitous discovery made by virtue of how it ended. We were able to perform critical operations shortly after landing in a scenario that closely parallels a trip to and landing on Mars. We demonstrated this from actual human performance, literally by accident. Operations in low earth orbit have utility for preparing missions beyond Earth. Crew countermeasures and essential hardware design will advance by using the space station. Autonomous crew operations abstract from Earth control will be learned. Empirical and basic solutions to problems in human physiology have promise to benefit not only future space exploration but the populations on Earth. The psychological aspects for true isolation will not be possible to experience until we venture to Mars. Earth from Mars will be a blue dot in the night sky and will surely give a meaning to the concept of isolation that explorers have not felt on Earth in perhaps 400 years.