Starship Asterisk*

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In early 2007 New Horizons flew through the Jupiter system, getting a speed-boost from the giant planet's gravity while snapping stunning, close-up images of Jupiter and its largest moons.

Fast forward to 2010 and New Horizons has given us another glimpse of old friend Jupiter, this time from a vantage point more than 16 times the distance between Earth and the Sun, and almost 1000 times as far away as when New Horizons reconnoitered Jupiter. While the planet is too far for the camera to pick up the swirling clouds and brewing, Earth-sized storms it saw just three years ago, "the picture is a dramatic reminder of just how far New Horizons, moving about a million miles a day, has traveled," says mission Principal Investigator Alan Stern, of the Southwest Research Institute.

The photo, one of three taken on June 24, also marked a successful test. Project Scientist Hal Weaver says the pictures were part of an Annual Checkout activity to have the Long Range Reconnaissance Imager (LORRI) "see" objects relatively close to the Sun (from LORRI's point of view). The angle between Jupiter, New Horizons and the Sun - known as the solar elongation angle - was only 17 degrees, and to the camera eye the nearby Sun was about 460 million times brighter than Jupiter.

We wanted to see how much stray sunlight would creep into these Jupiter pictures, especially since we'll make observations of the Pluto system in a similar geometry after the spacecraft passes Pluto in 2015," says Weaver, of the Johns Hopkins University Applied Physics Laboratory. "We generally prefer to look at targets in the opposite direction from the Sun. In fact, LORRI is calibrated for the low light we'll see in the Pluto system and Kuiper belt. Pointing too close to the Sun could damage the camera, but we decided it was safe to try to observe Jupiter. The observations were successfully executed and the images look great. LORRI was even able to resolve Ganymede, Jupiter's largest moon, and Europa, another of the Galilean satellites."

Although the Sun vastly outshines it, Jupiter was still a bright target for LORRI and the deep-space photo session required fast shutter speeds, with exposure times of only 0.009 sec. That's why the much smaller satellites appear so faint in the LORRI images.

Concluded mission PI Stern, "This haunting image of Jupiter - far in the distance back in the Sun's warmer clines from when New Horizons came - reminds us of Voyager's family postcard of the planets taken from beyond Neptune's orbit about 20 years ago. Perhaps after we flyby Pluto in 2015, we'll try something similar from our perch aboard New Horizons."

Annual Checkout Winds Down

Speaking of ACO-4: the mission's fourth annual checkout, which started on May 25, wraps up this week. "We packed a lot of activity into nine weeks," says Mission Operations Manager Alice Bowman, of APL. "It was very successful."

Read about ACO-4. The final activities included making sure the spacecraft's command and data handling system was in working order, and loading new navigation data into the spacecraft's guidance and control system, based on the June 30 trajectory-correction maneuver that refined New Horizons' path to Pluto. The Venetia Burney Student Dust Counter has also been turned on, now that the other six instruments in New Horizons science payload have been shut down. Working from commands transmitted last week to its computers, New Horizons will enter hibernation on Friday (July 30) and remain in electronic slumber until November. Operators at APL will monitor the craft through a weekly status beacon and a monthly transmission of housekeeping data.

Credit: NASA/JHU-APL/SRI

http://pluto.jhuapl.edu/

moving about a million miles a day

owlice wrote:

moving about a million miles a day

!!!

http://en.wikipedia.org/wiki/Helios_probes wrote:
<<The Helios I and Helios II space probes, also known as Helios-A and Helios-B, were a pair of probes launched into heliocentric orbit for the purpose of studying solar processes. A joint venture of the Federal Republic of Germany (West Germany) and NASA, the probes were launched from the John F. Kennedy Space Center at Cape Canaveral, Florida, on Dec. 10, 1974, and Jan. 15, 1976, respectively.

The probes are notable for having set a maximum speed record among spacecraft at 252,792 km/h (157,078 mi/h or 43.63 mi/s or 70.22 km/s or 0.000234c). Helios 2 flew three million kilometers closer to the Sun than Helios 1, achieving perihelion on 17 April 1976 at a record distance of 0.29 AU (or 43.432 million kilometers), slightly inside the orbit of Mercury. Helios 2 was sent into orbit 13 months after the launch of Helios 1. The Helios space probes completed their primary missions by the early 1980s, but they continued to send data up to 1985. The probes are no longer functional but still remain in their elliptical orbit around the Sun.>>

orin stepanek wrote:What a coincidence; today the Earth and Jupiter are equal distance from New Horizons at 17.82 AU. The Sun is at 17.88 AU from New Horizons. :

anna2222 wrote:Horizons is in the neighborhood of Saturn's orbital path at this point in time. I found a site that shows Horizon's countdown clock. If anybody is interested

orin stepanek wrote:H! "Anna2222" New Horizons is now close to the Orbital path of Uranus. It will pass the halfway point time wise in a couple of weeks. It's then; all down hill. :) http://www.nasa.gov/mission_pages/newho ... index.html

orin stepanek wrote:

anna2222 wrote:Horizons is in the neighborhood of Saturn's orbital path at this point in time. I found a site that shows Horizon's countdown clock. If anybody is interested

H! "Anna2222" New Horizons is now close to the Orbital path of Uranus. It will pass the halfway point time wise in a couple of weeks. It's then; all down hill. http://www.nasa.gov/mission_pages/newho ... index.html

Chris Peterson wrote:

orin stepanek wrote:H! "Anna2222" New Horizons is now close to the Orbital path of Uranus. It will pass the halfway point time wise in a couple of weeks. It's then; all down hill. http://www.nasa.gov/mission_pages/newho ... index.html

As a physicist, I'd have to argue that it really is uphill all the way. The only downhill bit was during the gravity assist from Jupiter in 2007. New Horizons continues to climb its way up the Sun's gravity well.

Chris Peterson wrote:

orin stepanek wrote:
New Horizons is now close to the Orbital path of Uranus. It will pass the halfway point time wise in a couple of weeks. It's then; all down hill. http://www.nasa.gov/mission_pages/newho ... index.html

As a physicist, I'd have to argue that it really is uphill all the way. The only downhill bit was during the gravity assist from Jupiter in 2007. New Horizons continues to climb its way up the Sun's gravity well.

orin stepanek wrote:
Hi! I wasn't talking about the gravity influence on Horizons; and I don't dispute your explanation of as much. I was referring to the fact that Horizons will reach the halfway mark as far as elapsed time is concerned. Maybe it's from my background; but it was considered that past the halfway mark is down hill. I know that the gravitational pull from the sun is influencing the spacecraft. Otherwise I doubt that it would be still slowing down.

neufer wrote:I was simply stating that Chris was wrong. :wink:

Chris Peterson wrote:

neufer wrote:I was simply stating that Chris was wrong.

Am I? I'm not saying I'm not, but I'm wondering if you did the calculations. Are you saying that from about 8 hours before passing Pluto, New Horizons will be increasing in speed relative to the Sun, or simply not decreasing quite as fast? It would be interesting to see a force vs. distance chart for the spacecraft trajectory.

Chris Peterson wrote:
In any case, even if there's an 8-hour slightly downhill stretch, it's been uphill since Jupiter, and will be uphill for at least tens of thousands of years after passing Pluto. Pluto isn't much more than a pothole in a continent-wide, uphill road trip.

=

http://en.wikipedia.org/wiki/Hill_sphere wrote:
<<An astronomical body's Hill sphere is the region in which it dominates the attraction of satellites. For a planet to retain a moon, the moon must have an orbit that lies within the Hill sphere of the planet. That moon would, in turn, have a Hill sphere of its own. Any object within that distance would tend to become a satellite of the moon, rather than of the planet itself. In more precise terms, the Hill sphere approximates the gravitational sphere of influence of a smaller body in the face of perturbations from a more massive body. It was defined by the American astronomer George William Hill, based upon the work of the French astronomer Édouard Roche. For this reason, it is also known as the Roche sphere (not to be confused with the Roche Limit). The Hill sphere extends between the Lagrangian points L1 and L2, which lie along the line of centers of the two bodies. The region of influence of the second body is shortest in that direction, and so it acts as the limiting factor for the size of the Hill sphere. Beyond that distance, a third object in orbit around the second (e.g. Jupiter) would spend at least part of its orbit outside the Hill sphere, and would be progressively perturbed by the tidal forces of the central body (e.g. the Sun), eventually ending up orbiting the latter.>>

neufer wrote:Pluto/Charon contributes only 150,000,000th of the mass of the solar system.

At 400,000 km New Horizons is sqrt(150,000,000) closer to Pluto/Charon than it is to the center of the rest of the solar system.

uphill for at least tens of thousands of years

jman wrote:Does that mean it will start decelerating at some point and would it ever roll back down?

BMAONE23 wrote:I"m not so sure it will decelerate. After all, aren't the Voyagers Accelerating?

Chris Peterson wrote:

BMAONE23 wrote:I"m not so sure it will decelerate. After all, aren't the Voyagers Accelerating?

No. Acceleration requires a force; the dominant force all our departing spacecraft experience is that of the Sun's gravity- a vector which is opposite their direction of motion, and therefore produces negative acceleration, aka deceleration.

bystander wrote:So, they are accelerating, negatively. :mrgreen:

orin stepanek wrote:
1731 16 58 45 Days Hours Min Sec Pluto Closest Approach In:

1731 00 00 15 Days Hours Min Sec
Timewise; New Horizons is past the halfway mark.

http://www.aycyas.com/thehighandthemighty.htm wrote:

THE HIGH AND THE MIGHTY (1954)

“I got news for you guys:
we just passed the point of no return.”

Click to play embedded YouTube video.

Click to play embedded YouTube video.

<<Early on, both Dan Roman and Miss Spalding observe a strange vibration within the cockpit; Spalding later notes two more such instances, each time when she is pouring drinks. John Sullivan is lying down when he becomes convinced that something is wrong with the plane, although no-one can identify its source. It is just past the flight’s point of no return – of course – when there are two loud bangs, the plane lurches, and one of the engines catches fire. The fire is extinguished, at which point it can be seen that the propeller has been lost, damaging the wing – and the fuel tank – in the process, while the engine itself hangs askew, adding to the drag on the plane.>>