The Real Challenges Of Space

Accordingly, I've carried my preoccupation with space travel into my professional life. Over the years, I've interviewed a number of astronauts: Frank Borman, Buzz Aldrin, Hoot Gibson and John Young. I've been to the Cape several times to witness Apollo and shuttle launches, flown the full-motion-based Space Shuttle simulator in Houston (seven approaches, five to Kennedy Space Center and two to Edwards AFB, only crashed once) and read everything I could find on the experience of seeing the Earth from space. Unless I win a really big lotto, I'll probably never see more than NASA documentary footage.

For me, space travel is an obsession, and I've learned that some of what we've been led to believe isn't true.

Yes, believe it or don't, Hollywood doesn't always get it right. The overriding attitude in Tinseltown is known as "suspension of disbelief." We all know what we're seeing isn't real, so why should the science that goes with it be any better?

Recently, many readers may have seen the exception to that rule---the movie Gravity---an amazing sci-fi film by Alfonso Cuarón that uses special effects to create a story realistically depicting space flight. Cuarón had input from four astronauts and two astrophysicists to verify the film's authenticity, and despite a few minor glitches, the experts agreed that Gravity was generally an accurate description of space travel.

That's rarely the case on most sci-fi depictions of flight outside the atmosphere. One common misunderstanding, for example, is that the Space Shuttle gradually transitions to zero-G as it makes its climb away from Earth, apparently on the premise that gravity becomes weaker at high altitude.

While it's true gravity does decrease with altitude, you probably wouldn't notice it in the first few thousand miles from Earth. Using the recently decommissioned fleet of Space Transportation System aircraft as examples, the shuttle typically orbited at about 370 miles, and the difference between one G at ground level and one G at 370 miles altitude would be hard to measure.

The 31 USAF Navstar satellites that transmit GPS coordinates orbit at 10,800 miles above Earth, and there might be a measurable difference in G-forces at that height.

(Gravity does decrease with altitude. On the 232,000-mile trip to the Moon, the Apollo spacecraft reached the neutral or Lagrangian point---where the Earth and Moon's gravity has equal authority---at about 190,000 miles out.)

If gravity seems to diminish to nothing in orbit, the nine-minute trip from launch to 370 miles altitude isn't quite so leisurely. In fact, the astronauts experience up to 4 Gs all the way to engine shutdown and orbital insertion, whereupon the onset of zero-G is practically instantaneous.

Another myth is that the shuttle, once established in orbit at 17,500 mph, remains belly down and nose forward with reference to Earth during the time it's in orbit.

If you think about it, that wouldn't make much sense. When the spacecraft is established in the desired orbit, gravity ceases to be a factor. The giant glider could circle the Earth at any attitude that was convenient, because zero-G is generated by free-fall equilibrium.

But even zero-G isn't constant in orbit. If the shuttle needs to maneuver, the slight acceleration will assert itself by pinning any loose objects (such as tools, food or crewmen) to the wall opposite the direction of travel.

Many of the experiments that need to be performed by the mission specialists are independent of the aircraft's attitude, so the spacecraft usually orbits inverted, belly up to the stars, to provide a good view of Earth. This obviously facilitates photography of the planet for aerial survey, weather observation or any other purpose. The shuttle has a selection of windows that look out the front, top and both sides to provide views in practically every direction.

Contrary to what practically everyone believes, space smells. The argument has always been that space couldn't possibly have any aroma since there's no air, but astronauts who have spent considerable time on EVAs (extra vehicular activity) have reported a "meaty-metallic scent." Others claim to have experienced the fruity smell of raspberry. NASA is at a loss to explain why.

Food in space presented NASA with some major challenges. The act of preparing and consuming food in zero-G is as much an art as a science, since anything left unattended tends to float away. For that reason, most food is in pouches. Some is dehydrated and must be rehydrated with water. Other food comes ready to eat. A crewman opens a tiny corner of the pouch, usually just large enough to accommodate a spoon, and eats in small bites. If something does drift away, it's important to track it down before it plugs up delicate instruments. NASA provides food on a 16-day cycle. The menu recycles every 16 days.

It can cost as much as $10,000/pound to put some items into orbit, so recycling is mandatory whenever possible. Water is a consumable that must be used carefully, and for that reason, every source of water on a spacecraft is critical. In other words, astronauts must become comfortable with drinking recycled urine. Space travelers report that once you adjust to the psychological stigma of drinking reprocessed wastewater, you really can't tell the difference. Some crew members report a slight taste of iodine, but other than that, reprocessed and fresh water taste about the same.

When it comes time for the de-orbit burn, the spacecraft reorients to fly tail first, fires the orbital maneuvering system (OMS) thrusters for a short burst to initiate deceleration, then maneuvers to a more conventional nose-first/belly-down attitude, so the 20,000 silica tiles on the bottom surface can deflect the heat of reentry. The shuttle needs to decelerate only about 200 mph to begin reentry.

Aerodynamic controls don't count for much in space, but they count for everything inside the atmosphere. As the spacecraft descends into thicker air, the elevator, ailerons, spoilers and rudder become more effective, and the world's largest glider maneuvers like a normal airplane, performing a series of turns to improve deceleration.
Perhaps the most gruesome question some people ask is, "What happens to an astronaut exposed to the airless, deep cold of space?" Movies have depicted the consequences of total decompression in graphic form for years.

The reality isn't nearly so gory, though the eventual consequences are usually the same. Russia had a rapid decompression of a Soyuz 11 spacecraft in 1971 during recovery. Automatic systems returned the aircraft to the recovery area in Kazakhstan, but all three cosmonauts were dead. They had been asphyxiated when the Soyuz decompressed above 62 miles (338,000 feet) altitude. The recovery team at first thought the three men were asleep, as there were no visible injuries.

NASA had a training accident in a simulator on the ground where a test subject was accidentally exposed to the equivalent of a deep space vacuum for more than a minute. He not only survived, but was basically uninjured.

No matter how matter-of-fact people become about space travel, it still remains a dangerous environment, with a multitude of risks we mere Earthlings will never appreciate.

But if that big lotto win will just come through, I'd still go.