Sun in the Way Will Affect Mars Missions in April

PASADENA, Calif. - The positions of the planets next month will mean diminishe communications between Earth and NASA's spacecraft at Mars.
Mars will be passing almost directly behind the sun, from Earth's perspective. The sun can easily disrupt radio transmissions between the two planets during that near-alignment. To prevent an impaired command from reaching an orbiter or rover, mission controllers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., are preparing to suspend sending any commands to spacecraft at Mars for weeks  in April. Transmissions from Mars to Earth will also be reduced.
The travels of Earth and Mars around the sun set up this arrangement, called a Mars solar conjunction, about once every 26 months.
"This is our sixth conjunction for Odyssey," said Chris Potts of JPL, mission manager for NASA's Mars Odyssey, which has been orbiting Mars since 2001. "We have plenty of useful experience dealing with them, though each conjunction is a little different."
The Mars solar conjunctions that occur once about every 26 months are not identical to each other. They can differ in exactly how close to directly behind the sun Mars gets, and they can differ in how active the sun is. The sun's activity, in terms of sunspots and solar flares, varies on a 22-year cycle.
This year, the apparent angle between Mars and the sun (if you could see Mars against the glare of the sun--but don't try, because it's dangerous to the eyes) will slim to 0.4 degree on April 17. The sun is in a more active period of solar flares for its current cycle, compared to the 2011 conjunction, but this cycle has been relatively mild.
"The biggest difference for this 2013 conjunction is having Curiosity on Mars," Potts said. Odyssey and the Mars Reconnaissance Orbiter relay almost all data coming from Curiosity and the Mars Exploration Rover Opportunity, as well as conducting the orbiters' own science observations.
Transmissions from Earth to the orbiters will be suspended while Mars and the sun are two degrees or less apart in the sky, from April 9 to 26, with restricted commanding during additional days before and after. Both orbiters will continue science observations on a reduced basis compared to usual operations. Both will receive and record data from the rovers. Odyssey will continue transmissions Earthward throughout April, although engineers anticipate some data dropouts, and the recorded data will be retransmitted later.
The Mars Reconnaissance Orbiter will go into a record-only mode on April 4. "For the entire conjunction period, we'll just be storing data on board," said Deputy Mission Manager Reid Thomas of JPL. He anticipates that the orbiter could have about 40 gigabits of data from its own science instruments and about 12 gigabits of data from Curiosity accumulated for sending to Earth around May 1.
NASA's Mars Exploration Rover Opportunity is approaching its fifth solar conjunction. Its team will send no commands between April 9 and April 26. The rover will continue science activities using a long-term set of commands to be sent beforehand.
"We are doing extra science planning work this month to develop almost three weeks of activity sequences for Opportunity to execute throughout conjunction," said Opportunity Mission Manager Alfonso Herrera of JPL. The activities during the conjunction period will not include any driving.
Curiosity, the newest asset on Mars, can also continue making science observations from the location where it will spend the conjunction period. Curiosity's controllers plan to suspend commanding from April 4 to May 1.
"We will maintain visibility of rover status two ways," said Torsten Zorn of JPL, conjunction planning leader for the mission's engineering operations team. "First, Curiosity will be sending daily beeps directly to Earth. Our second line of visibility is in the Odyssey relays."
JPL, a division of the California Institute of Technology, manages the projects operating both NASA Mars orbiters and both Mars rovers for NASA's Science Mission Directorate, Washington.

 

 

                                                                                                                           03.20.13



                                                                                                                                               

NASA Is Actually Working on Faster-than-Light Warp Drive

You know that scene in the film Contact where the “Machine” is spooling up, its three spinning rings kicking out crazy light and an electromagnetic field powerful enough to pitch nearby Navy battleships sideways, as Ellie (Jodie Foster) waits, terrified, in her tiny spherical craft above the space-time bedlam, to plummet into the vortex?
Yeah, that’s not exactly how NASA’s envisioning faster-than-light space travel, but…wait, NASA’s working on faster-than-light travel? Isn’t that impossible?
(MORE: Ultrafast Chips that Run on Light: Nanoswitch Breakthrough Brings Us Closer)
Of course it is. Nothing can travel faster than light, right? To do so would violate the special theory of relativity, which stipulates that you’d need an infinite amount of energy to accelerate a particle with mass to light speed. We’ve all heard this pretty much since we were kids. Has someone finally proven special relativity wrong?
Not at all, but with respect to travel between the stars, someone did come up with a radical-sounding hypothetical workaround 18 years ago.
In a paper titled “The Warp Drive: Hyper-fast travel within general relativity” published in science journal Classical and Quantum Gravity in May 1994, physicist Miguel Alcubierre suggested a mechanism for getting an object from one point to another at faster-than-light speeds without running afoul of Einsteinian relativity.
Alcubierre’s idea: bending space-time in front of and behind a vessel rather than attempting to propel the vessel itself at light-speeds.
According to Alcubierre, in the paper abstract …

… [it] is shown how, within the framework of general relativity and without the introduction of wormholes, it is possible to modify a spacetime in a way that allows a spaceship to travel with an arbitrarily large speed. By a purely local expansion of spacetime behind the spaceship and an opposite contraction in front of it, motion faster than the speed of light as seen by observers outside the disturbed region is possible. The resulting distortion is reminiscent of the ‘warp drive’ of science fiction.

Harold White

By placing a spheroid object between two regions of space-time — one expanding, the other contracting — Alcubierre theorized you could create a “warp bubble” that moves space-time around the object, effectively re-positioning it. In essence, you’d have the end result of faster-than-light travel without the object itself having to move (with respect to its local frame of reference) at light-speed or faster.
The only catch: Alcubierre says that, “just as happens with wormholes,” you’d need “exotic matter” (matter with “strange properties”) to distort space-time. And the amount of energy necessary to power that would be on par with — wait for it — the mass-energy of the planet Jupiter.
So we’re back to “fuhgeddaboudit,” right?
Maybe not. According to NASA physicist Harold White, the energy problem may actually be surmountable by simply tweaking the warp drive’s geometry.
White, who just shared his latest ideas at the 100 Year Starship 2012 Public Symposium, says that if you adjust the shape of the ring surrounding the object, from something that looks like a flat halo into something thicker and curvier, you could power Alcubierre’s warp drive with a mass roughly the size of NASA’s Voyager 1 probe.
In other words: reduction in energy requirements from a planet with a mass equivalent to over 300 Earths, down to an object that weighs just under 1,600 pounds.
What’s more, if you oscillate the space warp, White claims you could reduce the energy load even further.
“The findings I presented today change [Alcubierre's warp drive] from impractical to plausible and worth further investigation,” White told SPACE.com. “The additional energy reduction realized by oscillating the bubble intensity is an interesting conjecture that we will enjoy looking at in the lab.”
That’s right, an actual lab experiment, whereby White says he plans to simulate the tweaked Alcubierre drive in miniature, using lasers “to perturb space-time by one part in 10 million.”
And if it works? Don’t expect to go Alpha Centauri-hopping any time soon, but the idea well down the road, according to a presentation delivered by White on the subject last year, would involve a spacecraft leaving Earth, traveling a given distance using conventional propulsion, stopping (relative to the Earth), enabling its “warp field,” then traveling to a point near its interstellar destination, where it would then disable the field and continue on its way using conventional propulsion methods once more.
Star Trek meets Contact, in other words.
Instead of taking “decades or centuries,” White says this would allow us to visit a spot like Alpha Centauri — a little over four light years from us — in as little as “weeks or months.”
MORE: Penny for Your Rockets: Microthrusters Powered by Ion Beams Could Propel Satellites Through Space

Read more: http://techland.time.com/2012/09/19/nasa-actually-working-on-faster-than-light-warp-drive/#ixzz2NF8wbXYv

source : time tech