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Stardust to Return January 15
accessdeniednsp writes "Seven years ago, the Stardust probe was sent to intercept Comet Wild 2, gather dust particles, and return to Earth. Stardust is scheduled to touch down in a Utah desert on January 15. From the article: 'Our mission is called Stardust, in part because we believe some of the particles in the comet will, in fact, be older than the sun,' said Don Brownlee of the University of Washington, the principal investigator of the mission."
No kidding...especially since they were built by the same contractor (Lockheed Martin Denver).
The failure of Genesis was tied to a badly designed placement of deceleration sensors, a design flaw which Stardust is apparently free from (but I'm sure there will still be some serious hand-wringing on the 15th).
More details here.
Worst...sig...ever!
http://curious.astro.cornell.edu/question.php?num
Whenever the offence inspires less horror than the punishment, the rigour of penal law is obliged to give way...
Well, I believe his point was that it certainly can't be a virus. There's no way it could be compatible with any hosts, unless of course one subscribes to the Intelligent Design notion, in which case even though it has not evolved in this environment it could be compatible.
NASA/JPL requirements for an earth entry vehicle thats returning any kind of sample are very strict. They require that there be less than a 10^-6 chance of a particle larger than 2 nanometers entering the earth atmosphere.
Those NASA administrators read Crichton too.
It depends greatly on a couple factors:
Coefficient of drag, surface area, mass of the object, and the density of the air it's falling in.
If you assume that the object can survive the freefall from space, then the air changes density enough that it would slow to the terminal velocity of the object at approximately sea level regardless of how fast it was going (within a reasonable orbital velocity)
So to summarize a bit, it'd be easily possible to design a rough-surfaced sphere that could slow to well under 100mph. Just think of a ping-pong ball or a beach ball!
Another variable is the entry angle. Genesis was *targeted* such that it would hit the edge of the earth's atmosphere and utilize it to bleed off almost all of its kinetic energy through friction. The parachutes were only designed to take care of braking it that last 200 mph or so.
Of course, they never deployed, so it essentially hit the ground at terminal velocity - basically the same as if you had just rolled it out of an aircraft at 50,000 feet.
Worst...sig...ever!
Also, to add more, spheres show a very interesting behavior in different fluid flows: They're almost self-parachuting.
"The drag coefficient for a sphere is given with a range of values because the drag on a sphere is highly dependent on Reynolds number. Flow past a sphere, or cylinder, goes through a number of transitions with velocity. At very low velocity, a stable pair of vortices are formed on the downwind side. As velocity increases, the vortices become unstable and are alternately shed downstream. As velocity is increased even more, the boundary layer transitions to chaotic turbulent flow with vortices of many different scales being shed in a turbulent wake from the body. Each of these flow regimes produce a different amount of drag on the sphere."
To summarize that, basically at low speed, spheres form stable airflow which reduces drag substantially, whereas at high speeds, the sphere creates an uneven "wake" (much the way you might imagine a curveball behaving)
You're absolutely right. Your suggestion is silly.
A life form which evolved to survive on the surface of a comet has zero chance of being successful inside the human body. In order for a life form to evolve to be effective in an environment, it must have exposure to that environment. The viruses which already plague us here on Earth have spent billions of years evolving specifically to attack the other life forms already present on Earth.
Of course, this argument is strongly rooted in evolution. As some other posters have pointed out, if you believe in intelligent design, you might disagree. But then, real-life observations and evidence are overwhelmingly consistent with evolution, not intelligent design, so I think we're safe.