APHYS101 Exam 3
A moonwalk during an Apollo mission would last
7 hours - The life support system in the Apollo spacesuit provided enough oxygen for 7 hours. You could do multiple moonwalks during a mission, but each one would last only 7 hours. Now, by contrast, an entire Apollo mission, from initial launch to splashdown, could last anywhere from one to two weeks. One week was the minimum since it takes between 3 and 4 days to get to the Moon and another 3 or 4 days to get back to Earth.
The Apollo 1 fire, which killed three astronauts during a training exercise on the launch pad in 1967, was caused by
A short circuit in the Apollo capsule's electrical system AND The pure oxygen atmosphere in the Apollo capsule - Remember that in the 1960s, NASA always used PURE OXYGEN as the atmosphere the astronauts would breathe. This was necessary in order to make the spacecraft as light as possible - it would only need to carry enough oxygen for the crew to breathe, without having to lug along all the useless nitrogen that we normally breathe as well on the ground. Unfortunately the fact that NASA used pure oxygen at Earth normal pressure during this training exercise meant that even the smallest spark could cause a catastrophic fire. The spark was provided by a short circuit in the electrical system - this was due to faulty wiring.
The Moon's soil (regolith) is physically and chemically different from any soil found on Earth because, unlike the Earth, the Moon's surface has been
bombarded by micrometeorites for billions of years AND exposed to the solar wind for billions of years - The Moon has been geologically dead for billions of years, so tectonic activity and volcanic eruptions are not relevant. But due to the Moon's lack of atmosphere, the surface has been subject to bombardment by micrometeorites and the solar wind for all this time. The physical texture of the soil (very fine and powdery) is due to the micrometeorites, and the alien chemistry (the soil contains, for example, a rare form of helium not found on Earth) is due to the solar wind.
To get the Apollo 13 astronauts home on their damaged spacecraft before the life support ran out, it was necessary to
build carbon dioxide filters in the Lunar Module AND make a maneuver with the Lunar Module's descent engine - The Service Module on Apollo 13 was damaged beyond repair by an explosion. This meant the astronauts couldn't use its engine to speed them on their way home - this was done instead with the Lunar Module descent engine. Also, since the explosion had ruptured the oxygen tank on the SM that fed the Command Module's electrical system, the crew had to take shelter in the LM, which meant setting up additional carbon dioxide filters to prevent death by CO2 blood poisoning.
The robotic arm (Canadarm) on the Space Shuttle was used to
capture satellites in orbit for repair AND assist in attaching new modules to the International Space Station - difficult or dangerous to perform during a spacewalk.
On the International Space Station, water is
produced by the electrical fuel cells AND recycled from the atmosphere - Water is produced as a by-product of the chemical reaction that produces some of the station's electricity via hydrogen-oxygen fueld cells. On the station, moisture (from astronaut's exhalations, largely) is recaptured and filtered into drinkable water. This was not done on Shuttle missions since they were so short - so much water was produced by the Shuttle fuel cells that a lot of it was just dumped into space.
The job of the Space Shuttle's Solid Rocket Boosters (SRBs) and Space Shuttle Main Engines (SSMEs) was to
provide the thrust needed to get to orbit - Objectives (b) and (d) are achieved by the Orbital Maneuvering Subsystem (OMS), and (c) is taken care of by the Reaction Control Subsystem (RCS). Remember the SRBs provide 80% of the thrust during the first two minutes, then drop away. The SSMEs provide the other 20% of thrust for the first two minutes, and then ALL of the thrust to get most of the way to orbit. The OMS engines take over and get you all the way to orbit once the External Tank (ET) has been lost.
In April 2018, the first Chinese space station, Tiangong 1,
re-entered the atmosphere and burned up - Tiangong 1 was launched in 2011 and visited by several Chinese crews. It finally lost enough altitude to re-enter the atmosphere on April 1, 2018. There is another Chinese space station in orbit now, Tiangong 2, which was launched in 2016.
The most difficult component of the Gemini missions was
spacewalking - All of the answers here involved challenges for the crew, but by far the most difficult thing to do was perform a successful spacewalk (technically known as EVA, or extra-vehicular activity). The reason is that it turned out to be a lot harder than anyone had thought to maneuver around outside the spacecraft in zero gravity. The early spacewalks went badly because the astronauts would flail around and not be able to control their bodies' motion through space. Only on the last Gemini flight did they get it right - by establishing footholds to keep astronauts secured to the spacecraft, as well as developing tools that would work better in zero g.
In the 1950s, Wernher von Braun had a plan to send astronauts to the Moon by
stopping first at a large space station in Earth orbit - Project Apollo did involve direct launches from Earth. However, earlier in his career, von Braun had designed a large rotating space station that would be in low Earth orbit. Astronauts would launch from Earth to the space station and then leave for the Moon on small ships from the space station. This never got built (maybe someday)...
The main purpose of both the Russian Soyuz and the Chinese Shenzhou spacecraft is to
take people to and from space stations - These are manned spacecraft, only capable of reaching Low Earth Orbit, and with life support for just a couple of days. They are used solely to travel to and from space stations (Salyut, then Mir, then the ISS for Soyuz, Tiangong for Shenzhou).
When you are weightless, you tend to be
taller than when you're on the ground - The spongy disks between the vertebrae wil de-compress in zero gravity, lengthening the spine and causing you to grow a couple of inches (this is all in the torso, not the legs). Clothing and spacesuits worn on missions need to be able to accommodate this change in height.
The part of the Space Shuttle that would be recovered for re-use shortly after launch was
the Solid Rocket Boosters (SRB) - The SRBs are done by about 2 minutes after liftoff, and will splash down in the shallow coastal waters of the Atlantic, where they can be recovered for re-use. The External Tanks were never re-used since they had to be released shortly before reaching orbit and would always burn up in the atmosphere. The SSME's and the orbiters to which they were attached WERE re-used, but only after the mission was complete.
Which space stations could be expanded by adding on additional modules?
Mir AND International Space Station - Earlier stations in the 1970s (Salyut and Skylab) were what-you-see-is-what-you-get - no expandability. Mir revolutionized this in the 1980s, and the ISS is the ultimate expandable space habitat.
Spacesuits generally operate at low atmospheric pressure, in order to make them
More Felxible - Flexibility is the greatest challenge in spacecuit design - if you inflated the suit to Earth normale pressure it would be like living in a very stiff balloon during a spacewalk. The suit MUST operate at low pressure to allow you to flex your arms, legs, and fingers, and to bend at the waist.
The last three Apollo missions (15, 16, 17) were different from the earlier missions in that
the astronauts were on the Moon long enough to sleep in the Lunar Module AND they brought a rover for the astronauts to drive on the Moon - All Apollo missions launched from the Kennedy Space Center, and none of the landed on the far side (there would have been no way to communicate with Earth from there). But these were the longer missions... on Apollo 15, for example, was the first time the astronauts actually took off their space suits and went to sleep in the Lunar Module between moonwalks. These were also the missions that included the rover, used to ranger farther over the Moon's surface and collect more rock samples than would have been possible just by walking.
America's first space station, Skylab, was constructed from
the upper stage of an Apollo Saturn rocket - Skylab was actually part of the Apollo program, and together with the 1975 Apollo-Soyuz test project, made up the post-Moon-landing Apollo missions. It was made out of the third stage of the Saturn rocket, and crews would launch from Earth in an Apollo capsule and then dock with Skylab.
What are the main purposes of the Internaional Space Station?
to serve as a zero gravity laboratory AND to train astronauts for future missions to the Moon and Mars - Remember, all space stations so far have been zero-gravity laboratories. In the case of the ISS, many experts see it as a place for astronauts to practice the skills that will be needed for future missions further out into the solar system. It is not equipped to live on for more than 6 months at a time, though, and is not used to deploy satellites.
Training for a spacewalk is mostly done
under water - NASA's Neutral Buoyancy Simulator in Houston is where astronauts can put on spacesuits and practice their spacewalking skills underwater for hours at a stretch. Obviously the suit allows them to breathe underwater. It is also necessary to add weight to the suit in order to keep the astronaut from bobbing up to the surface (but not so much weight that they sink to the bottom - hence NEUTRAL buoyancy).
When wearing a spacesuit, your body is kept from overheating by
wearing a garment that carries cold water in pipes next to your skin - This is the Liquid Cooling Garment, which circulates chilled water next to your skin. The water is kept chilled by a refrigeration unit in the suit.
Which of the following happens as a result of the re-distribution of fluids in your body in zero gravity?
your legs get thinner, your nose and sinuses get congested AND you feel like you have to pee a lot - Your brain gets plenty of blood in zero gravity - the heart has an easier time pumping blood to the head than it did in normal gravity. But because of the behavior of fluids in zero gravity, all the liquids in your body will shift upward as they try to form a sphere (but can't since they're trapped inside you). This means your legs lose fluid and get thinner; your head gets filled with fluid, which makes you feel congested, as well as fooling your brain into thinking you're got too much water and need to eliminate some.
Which of the following spacecraft could land on dry land rather than splashing down in the ocean?
Space Shuttle, Soyuz AND Shenzhou - The Shuttle, of course, landed as a glider on a runway. The Russian (Soyuz) and Chinese (Shenzhou) descent modules land in remote areas, near the launch facilities of these two countries. The early NASA capsules always splashed down in the Atlantic, which is also the plan for the Orion capsule that will be the next ride NASA is planning to provide into space.
The International Space Station would re-enter the atmosphere and burn up if it weren't re-boosted to higher altitude every 6 months or so.
TRUE - Any craft that's going to stay in a low Earth orbit for many years needs to be able to fight the slight but inevitable push of the Earth's thin atmosphere out there, which will lead to re-entry in under a year at the altitude of the Space Station. The Station doesn't have its own propulsion, so this is achieved by a Russian Soyuz or Progress vessel while it's docked to the ISS.
During a spacewalk, astronauts will usually keep themselves attached to the spacecraft by the use of strap-like foot restraints.
TRUE - This is the only way you can do anything useful on the surface of a spacecraft... otherwise you'll keep floating away from the craft every time you even touch it lightly, due to Newton's law of recoil. Generally you will have a tether to keep you from actually floating away forever, but still, you want to keep yourself anchored, so the foot restraints are necessary. They figured this out during the Gemini program.
Since 2000, the International Space Station has been continually inhabited by crews of 3 to 6 astronauts.
TRUE - Yes... this is because in 2000 the life support module (the Russian component called Zvezda) was added to the space station. At first it had a crew of 3, but as the station was expanded it soon was able to accommodate a crew of 6. Since 2000 it's never been empty!
The only part of the Apollo spacecraft that returned safely to Earth was the
Command Module (CM) - The Command module is the only part of the spacecraft designed to survive re-entry to the Earth's atmosphere. It is the only part that had a heat shield (ablation shield, it was called) to protect the crew as the atomsphere heated up during the descent. Just prior to entering the atmosphere the Service Module was jettisoned and the Command Module turned around so that the heat shield would hit the atmosphere first.
The astronauts on the International Space Station are weightless because there is no gravity in space.
FALSE - Aw, c'mon, you know this isn't true! It's the Earth's (still quite strong) gravity that keeps the ISS in orbit! Remember, the gravity at the altitude of the ISS is still about 90% of what it is on the ground. What causes weightlessness is the MOTION of the ISS - the fact that it's in orbit, which is a type of freefall. When you're in freefall down near the Earth, you are also weightless, and for the same reason that the astronauts are! This is why astronauts CAN train for weightlessness down on or closer to the ground - they can get true weightlessness for 20-25 seconds at a time on an airplane, or mock weightlessness for hours at a time underwater.
While the earlier Apollo missions landed on the Moon's near side, the later missions landed on and explored the far side.
FALSE - No probe, manned or unmanned, has ever landed on the far side of the Moon. The problem is, we would have no communications from Earth with the spacecraft, since the Earth would always be below the lunar horizon as viewed from the landing site. In the future, we could begin exploring the far side of the Moon and still have contact with Earth, IF we put a set of communications satellites in lunar orbit that also could be seen from Earth.
Astronauts are always weightless when they're in space.
FALSE - No, it's being in FREEFALL that makes you weightless. What being in space allows you to do is to be in freefall for a LONG TIME (months, years, or longer). This is because orbital motion is just a type of freefall motion where you're going to fast to ever fall to the ground. But note... if you're on a spacecraft, in space, you won't be weightless if you turn on the engines (which means you're no longer in freefall).
Wernher von Braun supported the Lunar Orbit Rendezvous mission plan for the Apollo program from the very beginning.
FALSE - No, von Braun favored Earth Orbit Assembly, until he and his team were convinced by John Houbolt to use Lunar Orbit Rendezvous. The advantage of LOR is that it made the spacecraft much less massive, so easier to launch from Earth and also much easier to land on the Moon (although in LOR only two astronauts could go down to the Moon while the third awaited them in the Command Module).
The Apollo spacecraft launched from Earth with the Command and Lunar modules joined together.
FALSE - Nope... the purpose of the turnaround maneuver, shortly after Trans-Lunar Injection (TLI, or leaving Earth orbit), is to join together the CM and LM for the first time. The CM and LM are not docked together at launch because then there would be no way to get the astronauts and the LM safely into orbit.
The mission plan that NASA used for its moon landings was called
Lunar Orbit Rendezvous - All three approaches were considered, but the first two had problems. Direct Ascent involved sending the crew directly to the Moon in a large spacecraft that would land all three crew members on the lunar surface. This didn't work because the launch vehicle would have needed to be HUGE - too big to build in a reasonable amount of time. Earth Orbit Assembly was Wernher von Braun's favored approach at first - you would break the large moon-landing craft into two pieces, launch them separately (requiring two launches) using a Saturn rocket, something we COULD build, and then assembling in space. But again, the moon lander in this scheme is BIG, and problems were anticipated with trying to bring it down gently onto the moon's surface. Lunar Orbit Rendezvous (LOR), as argued by the engineer John Houbolt, would only take 2 of the 3 astronauts down to walk on the Moon, but had the advantage of making the spacecraft MUCH lighter, so it could be launched all at once from Earth on a SINGLE Saturn V, and so that the landing on the moon would be much easier given the smaller craft. It's called LOR because after leaving the Moon, the two astronauts need to rendezvous and dock with the command module, rejoining their third crewmate, to go home. Note that TWO dockings of the Command and Lunar modules are required in this plan - once after turnaround and once after Lunar Orbit Rendezvous.
Attitude control on the Shuttle was provided by the
Reaction Control Subsystem (RCS) - All spacecraft have a RCS system, whose purpose is always to control the craft's attitude. Remember the SRBs and SSMEs are used to provide thrust during launch, and the OMS engines are used to enter orbit, change orbits, and then de-orbit.
Which of the following spacecraft can people currently ride in to get to a space station?
Soyuz AND Shenzhou - Space-X and Boeing will SOON be providing rides to the ISS, but that hasn't started happening yet. The Space Shuttle fleet stopped flying in 2011. So that leaves the Russian Soyuz, which can take people to the ISS, and the Chinese Shenzhou, which can take people to the Tiangong 2 station.
Entering lunar orbit (LOI) and leaving lunar orbit (TEI) are both achieved using the
Service Module (SM) engine - The Saturn V is used for getting off the Earth and for leaving Earth orbit (TLI). The lunar module descent stage is used by two astronauts to land on the Moon. And solid rocket boosters (SRBs) have no place in an Apollo mission (they are a part of the Space Shuttle). No, indeed the Service Module (SM) was designed to be used for these two purposes: entering and leaving lunar orbit.
Which engine system did the Space Shuttle use during the landing on Earth?
The amazing thing about the Shuttle is that it landed with no engine power at all, functioning as a glider.
The only time that a crew has ever needed to use a launch abort system (escape pod) to save their lives was on
a Soyuz mission - All of these programs except the Shuttle had launch abort systems... but only once, on a Soyuz in the 1980s, a crew needed to eject due to a spill of kerosene on the launch pad which ignited. Note that NASA's upcoming Space Launch System (SLS) will also include a launch abort system.
The "rendezvous" in an Apollo mission occurs
a few minutes after leaving the lunar surface - Just making sure y'all know this is "Lunar Orbit Rendezvous", and involves the two moonwalkers re-joining their crewmate in the Command Module in while in lunar orbit.
On the International Space Station (ISS), spacewalkers have remained close to their spacecraft by using
a long tether to attach the astronaut to the spacecraft - I gave you incorrect information in class! I said that untethered spacewalks began on the Shuttle in the 1980s, which is true... however, tethered spacewalks are still the norm, and this is certainly the case on the ISS. The astronauts also do have a backpack called SAFER, which is for emergencies only, and is a small jetpack that allows a spacewalker to get back to the ISS in the event that their tether breaks.
The failure of an elastic O-ring on the final launch of the Space Shuttle Challenger led to the death of the crew because it ultimately caused
an explosion in the shuttle's hydrogen tank - The O-ring was supposed to help seal one of the Solid Rocket Boosters (SRB), but it failed, so there was an exhaust leak after ignition, which pushed the SRB into the side of the External Tank (ET), rupturing it and causing the hydrogen supply to explode.
The most relaxed posture in zero gravity includes
arms floating at chest height - You often see astronauts using tools or typing on laptop computers positioned near chest level rather than waist level - this is because in zero gravity your arms will float at chest height when relaxed. This means that when you sleep in zero gravity, your arms float out in front of your chest! The legs will not be straight, since this requires effort in zero gravity, and your head will actually be tilted upward rather than down.
Astronauts generally breathe pure oxygen for a few hours before putting on a spacesuit, in order to
get rid of all the dissolved nitrogen from the bloodstream - The big danger here is the one also faced by deep-sea divers who re-surface too quickly: the bends, or decompression sickness. Spacesuits always use a pure oxygen atmosphere at low pressure... normally, we breathe a mostly nitrogen atmosphere at higher pressure, which means there's a lot of nitrogen dissolved in the bloodstream. Normally this doensn't pose a problem... but if you reduce the pressure too quickly without first breathing pure oxygen for a while, the nitrogen comes out of solutions and forms bubbles in the bloodstream. This can be painful and potentially lethal if bubbles form in the brain or heart. Wearing the oxygen mask at normal pressure prior to putting on the suit and de-pressurizing allows you to slowly get rid of the nitrogen first.
The typical Russian spacesuit design differs from the NASA design in that it
is pre-assembled rather than requiring assembly from modular pieces AND operates at a higher pressure and is less flexible - The Russian suit design is pre-assembled, so you can put it on very quickly by just climbing in through a door in the back. A disadvantage of this is that suits generally only fit a limited range of sizes, whereas the modular NASA design allows for a wider range of physical statures. Also, the Russian suit does operate at a higher pressure, which makes it quicker to put on (you don't need to pre-breathe oxygen for nearly as long as before putting on a NASA suit), but also less flexible and harder to maneuver in. Generally both types of suits are tethered.
The large Pressurized Mating Adapters (PMA) on the International Space Station have been used to
join together American and Russian station components AND provide a docking port for the Space Shuttle - The two halves of the Space Station are built to very different specifications, American and Russian. The hatchways do not match up and so you can't attach a Russian component to an American piece without an adapter. Also, the Shuttle had been fitted with a docking port in the 1990s which allowed it to connect to the Russian Mir station - so, ironically, the Shuttle could dock to a Russian module of the ISS but not an American module. To dock to an American module required that an adapter be sticking out with the Russian end exposed.
Suppose that the Space Shuttle is in orbit, drifting to the east, with its Orbital Maneuvering Subsystem (OMS) nozzles pointing to the west. When it's time to return to Earth, the Shuttle must
make a 180-degree yaw maneuver and then fire its OMS engines to de-orbit - To return home, the Shuttle must slow down, which it can't do if the nozzle is pointing toward where the Shuttle has already been. It needs to be turned backward, for which the only viable option of those presented is a 180 degree yaw maneuver.
After the crew of the shuttle Columbia died due to damage to its wing sustained during the launch, NASA decided to
make it possible to monitor the Shuttle much more carefully for damage - It wasn't possible to re-engineer the wings, so NASA installed many new sensors on the Shuttle to monitor for damage which could then be fixed by spacewalkers during a mission. The Shuttle was still seen as necessary in completing the ISS, so it did continue flying until ISS completion in 2011.
The Orbital Maneuvering Subsystem (OMS) engines on the Space Shuttle were used for
making velocity changes while the Shuttle was in orbit, providing the final thrust needed to reach orbit AND de-orbiting the Shuttle and allowing it to return to Earth - The initial thrust (shortly after launch) is provided by the SRBs and SSMEs. The OMS engines are fired for the first time to provide the final bit of thrust needed to reach orbit (orbital insertion), and are then used many times during a mission to change velocity and therefore change orbits. The final use of the OMS is the de-orbital burn.
Training for the zero-gravity space experience can be done
on an airplane AND under water - Since weightlessness is a result of being in freefall, it is possible to experience true weightlessness for 20 - 25 second intervals on an airplane that's flying in a parabolic trajectory. You can also experience something LIKE weightlessness (although it's not the real thing) in an underwater setting, and NASA has been doing this since the Apollo days.
Throughout the history of spaceflight, astronauts have died
on the launch pad, shortly after liftoff AND during re-entry to the atmosphere - So far, no one has died while in space. The Apollo 1 astronauts died during a fire on the launch pad; the Challenger astronauts died shortly after launch, still low in the atmosphere; the Columbia crew and one of the early Soyuz crews died during re-entry.
Many astronauts get dizzy and nauseous on their first trip into space. This is due to
problems in the inner ears due to zero gravity - It's the otolith organs in the inner ears that cause the problem. Normally these hang down, and then direction they hang in tells your brain which way is down. In zero gravity these organs float, so your brain gets confused, which can lead to dizziness and nausea.
