Monday, November 09, 2009

Frequently Asked Questions (FAQs)

1. Q. Why the title? Why did you title your volumes "The Stars, My Destination"?

A. "The Stars, My Destination" is a science fiction novel written by Alfred Bester about 50 years ago. Alfred B. picked a great title for a great book, but I borrowed his title only because it describes following enterprise. There is absolutely no other parallel between Alfred's great book and my enterprise; however, you should read both. Bester's book is a fun read. Wikipedia Affiliate Button(For an abbreviated version, see the entry in Wikipedia.)

2. Q. Why go? Why go to the planets at all? Can't we just stay on Earth?
A. As long as Mother Earth is a pleasant place to live, no one should have to leave unless they want to.

On the other hand, some people will want to go for various reasons: scientific, philosophical, religious, environmental, and so on. These volumes assume the reason humans will leave enmasse is economic. Large scale enterprises will launch and maintain huge space complexes for purely economic reasons.

I won't go there except to say:"If typical missions to Mars take four years, and they have to be timed to take advantage of certain orbital orientations; then, human travel to the planets probably won't ever happen in a meaningful way.On the other hand, if typical missions take four days to get to Mars, four days to return, and they can happen anytime; then, it's likely that human travel to the planets will become routine."

3. Q. How can you accelerate to the planets?

A. I touch upon this later in this volume. I certainly don't have the expertise to elaborate on it. This portion discusses "why" not "how".

4. Q. How much will it cost?A. I think a 4 year constant speed mission will cost considerably more then a four day flight (at constant acceleration) to Mars. Right now, I have no idea how much it will cost to design, develop, build and deploy a spacecraft which can accelerate at force of gravity.

5. Q. Why not "Accelerate to the Stars"? Why stop at the planets? After all, the title is named after Bester's novel, "The Stars, My Destination".

A. First, I think it's logical to consider traveling to the planets as a necessary precursor to interstellar travel.Second, simple calculations indicate that accelerating to the planets can take days while the same acceleration would take years to reach even the nearest star.Third, traveling to stars will require relativistic speeds which will complicate things.Fourth, we have yet to accelerate anywhere, not even the nearest planet; but we can speculate about stars as well as planets.In any event, I discuss insterstellar travel in the second volume.REASONS: Following are a few benefits from accelerating at force of g to the planets. I tried to group them, but many benefits could be placed in several groups.Much shorter duration of the spaceflight would yield following benefits:---Human endurance (aka "patience") would not have to be as great.---Decreased need for consumables (i.e., food and other supplies).---Life support needs decrease considerably.---Public interest would be less likely to wane during the mission.---Much less exposure to interplanetary radiation.MEDICAL BENEFITS would come from simulating gravity by constant acceleration. Thus, crews could avoid following medical anomalies from prolonged zero g.
1. Health Effects. "Humans are well suited to life on the surface of the Earth. When weightless, certain physiological systems begin to alter; then, both temporary and long term health issues can occur. The most significant adverse effects of long-term weightlessness are muscle atrophy and deterioration of the skeleton; these effects can be minimized through a regimen of exercise. Other significant effects include fluid redistribution, a slowing of the cardiovascular system, decreased production of red blood cells, balance disorders, and a weakening of the immune system. Lesser symptoms include loss of body mass, nasal congestion, sleep disturbance, excess flatulence, and puffiness of the face."
2. Space Bones."Weightlessness sure looks like a lot of fun, but prolonged exposure to zero-G in space can have some negative side effects -- like the weakening of human bones!"
3. Human Effect of Zero-G. "The human effect of being in the zero-gravity (0-G) environment of space to the one-gravity (1-G) of Earth was evident at a press conference in Houston when NASA astronaut Ms. Heidemarie Stefanyshyn-Piper, 43, collapsed twice in a matter of minutes after her return from less than two-weeks in the microgravity of space. .... Astronauts typically lose 10 percent to 14 percent of their blood volume while in space, regaining it in a day or two.NASA is now beginning to focus medical research on the human effects of long-duration space flight in preparation for a trek to Mars in 2030. Heidemarie shows that the adjustment to Mars gravity after a 6-month trek to the Red Planet could be a challenge to humans."
Following benefits derive indirectly from "g-force" space missions.
--Convenience from not having to "learn" to live in extended zero g conditions.
--Payload (for mission) would be greater because less weight and volume would have to be dedicated to consumables and life support.
--Hulls could be thicker which would further help shield onboard humans from radiation.
--Crew compatibility would be less of a concern, because the crew would not have to spend as long a time in close quarters.
--Navigation would be much easier. Flying at constant speed now means a Hohman transfer orbit to reach the destination. Flying at constant acceleration means that you fly at more of a "straight line" directly from Earth to destination planet. In a flight to Mars, navigator could point the ship directly to Mars (not to where Mars will be in six months).

Following example of most newspapers, I plan to write in content and style to be readable to sixth graders (or even younger), I'd like to point out a few simple things. My goals are readability, clarity, and enjoyment. At the very least, I hope to make the blogs fun to write.Comments are welcome from anyone.

Q. Why do we care about our spacecraft's light speed??
A. For interplanetary flights, we don't care. Even at g-force acceleration, relativity is not a factor. Such flights will take a few days, and we don't even reach 1% c until after three days.
On the other hand, we care a lot about relativistic effects for interstellar flights. Even with g-force acceleration, those flights will take years. (At constant velocity, interstellar flights would take generations if not centuries.) After 300 days of g-force acceleration, we will have not even approached the Oort Cloud (could be considered Solar System's "shell"), but spaceship's velocity will have reached .866c. At this relativistic speed, spaceship's mass has doubled, and inflight time slows to 50% of time experienced by observers at relative rest. (Example: travel time to Alpha Centauri will be two years to starship occupants, but Earth bound observers will experience four years.) By the time, we'll doing interstellar missions, we'll likely have some solutions for this relativistic phenomena.

Q. Why mixed units?

A. We can easily contrast inflight velocities with e, Earth's escape velocity, 11 km/sec. This is the velocity needed to exit Earth's gravitational field and travel to other locations in our Solar System. By using "kilometers per second" in all the numerators; we can easily judge how long we must accelerate (at g) to achieve that speed. We can readily ascertain it will take minutes and not hours. An easy calculation (11 km/sec divided by 0.6 km/sec per minute) readily tells us it would take 18 and 1/3 minutes to achieve that speed.
Finally, note the daily rate of g (864 km/sec per day). After one day acceleration at g, we will have greatly exceeded e


Post a Comment

Links to this post:

Create a Link

<< Home