APOD: Juno Rockets Toward Jupiter (2011 Aug 09)

[APOD Robot]

Juno Rockets Toward Jupiter

Explanation: Next stop: Jupiter. Last week included one of the few times in history that humanity launched something completely off the Earth, moving away so fast that it will never return. Well, almost -- Juno's planned trajectory actually brings it homeward bound in about two years, zipping by, this time using the Earth's gravity to pull it to an even higher speed, high enough to reach Jupiter. The above video depicts the launch of Juno aboard a Atlas V rocket. When the robotic Juno spacecraft reaches Jupiter in 2016, it will spend just over a year circling the Solar System's largest planet, using its unique cadre of instruments to probe the planet, sending back clues of its structure and origin. Then Juno will be instructed to dive into the thick atmosphere of the Jovian giant, taking as much data as it can before it melts.

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[LoneStarG84]

Last week included one of the few times in history that humanity launched something completely off the Earth, moving away so fast that it will never return.

What were the others?

[Wolf Kotenberg]

Love those rocket cams. Too bad they didn't have one on the EROS lander. Movies bring out so much detail. Too bad there was no movies of the rovers bouncing around on MARS from a " parachute cam ".

[starstruck]

Last week included one of the few times in history that humanity launched something completely off the Earth, moving away so fast that it will never return.

What were the others?

Guess that would be Voyagers 1 and 2 . . they're not coming back. Maybe there are others too.

Very nice video, particularly enjoyed seeing the rocket cam looking back down towards the launch site and the SRB separation.

[owlice]

"Conquering the Gas Giant"!!

: falls over laughing :

[RogerAF]

When I access this video, it looks more like a roman temple than a rocket:


How do I post a screen shot?

[bystander]

Click to play embedded YouTube video.

Atlas V JUNO Launch Highlights
United Launch Alliance | 2011 Aug 08

http://asterisk.apod.com/viewtopic.php?t=24740#p154474

[Guest]

Juno is traveling 630 million km after using gravity assists to slingshot itself to a higher velocity, and yet I'm still intrigued and impressed to watch that rocket physically "break" the "sound barrier" in that clip just after the announcement of reaching Mach 1, an amazing sight and phenomenon in itself.

http://en.wikipedia.org/wiki/Prandtl-Gl ... ingularity
[E]xtreme atmospheric conditions are produced which may give rise to a vapor cone, shock collar, or shock egg of visible condensation....Since heat does not leave the affected air mass, this change of pressure is adiabatic, with an associated change of temperature. In humid air, the drop in temperature in the most rarefied portion of the shock wave (close to the aircraft) can bring the air temperature below its dew point, at which moisture condenses to form a visible cloud of microscopic water droplets. Since the pressure effect of the wave is reduced by its expansion (the same pressure effect is spread over a larger radius), the vapor effect also has a limited radius....These condensation clouds were frequently seen during Space Shuttle launches around 25 to 33 seconds after launch when the vehicle is traveling at transonic speeds.

[orin stepanek]

Then Juno will be instructed to dive into the thick atmosphere of the Jovian giant, taking as much data as it can before it melts.

I wish it could just fly around in the upper atmosphere and collect information before plunging down lower where it must be pretty hot to be melted like a blob of ice.

[NoelC]

I love the way that when the rocket gets wayyy up there, into space, the thrust from the engines spreads out, clearly indicating there's no more atmosphere blowing it back.

I find it interesting that modern rocketry is returning to its ancient origins (noting that fireworks and solid fuel boosters have something in common).

I'll Echo Orin's comment... Why, if we're sending something all the way to Jupiter, after the orbital phase does it have to be a one-time drop into obvlivion? Haven't the Mars rovers shown us that a well-designed, durable probe can keep good scientific observations coming back for a long time? Is it that we just don't know enough about what's happening in Jupiter's atmosphere yet to even try such a feat (e.g., via a smart glider or even a powered plane)?

-Noel

[Chris Peterson]

I'll Echo Orin's comment... Why, if we're sending something all the way to Jupiter, after the orbital phase does it have to be a one-time drop into obvlivion? Haven't the Mars rovers shown us that a well-designed, durable probe can keep good scientific observations coming back for a long time? Is it that we just don't know enough about what's happening in Jupiter's atmosphere yet to even try such a feat (e.g., via a smart glider or even a powered plane)?

It is very difficult to get something from space onto a planet with an atmosphere. Juno cannot (ballistically) enter Jupiter's atmosphere at less than about 45 km/s (its orbital velocity). Compare that with reentering Earth probes at 8 km/s. Juno isn't going to burn up because the atmosphere is hot, but because it will become a meteor. And it will do so very high in the atmosphere, where it is cold and tenuous.

[neufer]

I'll Echo Orin's comment... Why, if we're sending something all the way to Jupiter, after the orbital phase does it have to be a one-time drop into obvlivion?

Like Galileo, Juno must not contaminate Europa even by accident.

"ALL THESE WORLDS ARE YOURS EXCEPT EUROPA.
ATTEMPT NO (accidental crash) LANDING THERE."

Is it that we just don't know enough about what's happening in Jupiter's atmosphere yet to even try such a feat (e.g., via a smart glider or even a powered plane)?

Juno is specially designed for remote sensing of the atmosphere and in situ measurements of the radiation belts and magnetic fields.

Juno is already extremely heavy since it had to be built like a tank specifically to shield itself from radiation in orbit.

Juno was NOT designed to be a reentry probe with

• 1) a heat shield,
  2) deceleration strengthening,
  3) some sort of parachute (or wings) and
  4) a communications system able to reach all the way back to Earth.

Besides, Jupiter's upper atmosphere has already been successful probed in situ
by an auxiliary Galileo probe (with information relayed by Galileo itself):

---

---

<<An atmospheric probe was released from the Galileo spacecraft in July 1995, entering the planet's atmosphere on December 7. It parachuted through 150 km of the atmosphere, collected data for 57.6 minutes, and was crushed by the pressure to which it was subjected by that time (about 22 times Earth normal, at a temperature of 153 °C). It would have melted thereafter, and possibly vaporized. The Galileo orbiter itself experienced a more rapid version of the same fate when it was deliberately steered into the planet on September 21, 2003, at a speed of over 50 km/s, to avoid any possibility of it crashing into and possibly contaminating Europa—a moon which has been hypothesized to have the possibility of harboring life.

The 339-kilogram atmospheric probe, built by Hughes Aircraft Company at its El Segundo, California plant, measured about 1.3 meters across. Inside the heat shield, the scientific instruments were protected from ferocious heat during entry. The probe had to withstand extreme heat and pressure on its high-speed journey into the Jovian atmosphere, traveling at 47.8 km/s.

The probe was released from the main spacecraft in July 1995, five months before reaching Jupiter, and entered Jupiter's atmosphere with no braking beforehand. The probe was slowed from its arrival speed of about 47 kilometers per second to subsonic speed in less than two minutes. This was by far the most difficult atmospheric entry ever attempted; the probe had to withstand 230 g and the probe's 152 kg heat shield, making up almost half of the probe's total mass, lost 80 kg during the entry. NASA built a special laboratory, the Giant Planet Facility, to simulate the heat load, which was similar to that of an ICBM-style straight-down reentry through a thermonuclear fireball. It then deployed its 2.5-meter parachute, and dropped its heat shield.

As the probe descended through 150 kilometers of the top layers of the Jovian atmosphere, it collected 58 minutes of data on the local weather. It only stopped transmitting when ambient pressure exceeded 23 atmospheres and temperature reached 153 °C. The data was sent to the spacecraft overhead, then transmitted back to Earth. Each of 2 L-band transmitters operated at 128 bits per second and sent nearly identical streams of scientific data to the orbiter. All the probe's electronics were powered by lithium sulfur dioxide (LiSO₂) batteries that provided a nominal power output of about 580 watts with an estimated capacity of about 21 ampere-hours on arrival at Jupiter.

The probe included six [specialized sounding] instruments for taking data on its plunge into Jupiter:

• an atmospheric structure instrument group measuring temperature, pressure and deceleration,
  a neutral mass spectrometer and
  a helium-abundance interferometer supporting atmospheric composition studies,
  a nephelometer for cloud location and cloud-particle observations,
  a net-flux radiometer measuring the difference between upward and downward radiant flux at each altitude, and
  a lightning/radio-emission instrument with an energetic-particle detector that measured light and radio emissions associated with lightning and energetic particles in Jupiter's radiation belts.

Total data returned from the probe was about 3.5 megabits. The probe stopped transmitting before the line of sight link with the orbiter was cut. The likely proximal cause of the final probe failure was overheating, which sensors indicated before signal loss.

The atmosphere through which the probe descended was somewhat hotter and more turbulent than expected. The probe was eventually completely destroyed as it continued to descend. The parachute would have melted first, roughly 30 minutes after entry, then the aluminum components after another 40 minutes of free fall. The titanium structure would have lasted 6.5 hours more before disintegrating. Due to the high pressure, the droplets of metals from the probe would finally have vaporized once their critical temperature had been reached, and mixed with Jupiter's liquid metallic hydrogen interior.>>

[NoelC]

Juno isn't going to burn up because the atmosphere is hot, but because it will become a meteor.

So what, they couldn't design an orbiter to continue to send useful data / pictures for longer than a year? Is it going to run out of gas? Maybe become brain damaged from the radiation belts?

My question still stands, though at a higher level: Why drop it in and burn it up?

-Noel

[neufer]

Juno isn't going to burn up because the atmosphere is hot, but because it will become a meteor.

So what, they couldn't design an orbiter to continue to send useful data / pictures for longer than a year?

There is probably no pressing reason why Juno can't continue to send useful data / pictures for longer than a year but it would be very expensive to a priori built it to specs that gives it a reasonable chance to do so.

(Of course the Tea Party might decide to pull the plug on Juno before she even reaches Jupiter.)

Is it going to run out of gas? Maybe become brain damaged from the radiation belts?

Yes. Galileo's prime mission to Jupiter was a two-year study from December 7, 1995 to December 7, 1997. Galileo's extended mission ran to September 21, 2003 after it did, in fact, start "to run out of gas." However, Galileo's cameras were already deactivated on January 17, 2002, after they had sustained irreparable radiation damage.

My question still stands, though at a higher level: Why drop it in and burn it up?

My answer still stands, though at a higher level:

Like Galileo, Juno must not contaminate Europa even by accident
Hence it must be dropped into Jupiter while it still has the brains and gas to do so.

[c]"ALL THESE WORLDS ARE YOURS EXCEPT EUROPA.
ATTEMPT NO (accidental crash) LANDING THERE."[/c]

<<Galileo arrived at Jupiter on December 7, 1995. Galileo's prime mission was a two-year study of the Jovian system. The spacecraft traveled around Jupiter in elongated ellipses, each orbit lasting about two months. Once Galileo's prime mission was concluded, an extended mission followed, starting on December 7, 1997; the spacecraft made a number of daring close flybys of Jupiter's moons Europa and Io. The closest approach was 180 km (112 mi) on October 15, 2001. The radiation environment near Io in particular was very unhealthy for Galileo's systems, and so these flybys were saved for the extended mission when loss of the spacecraft would be more acceptable. The uniquely harsh radiation environment at Jupiter caused over 20 anomalies. Despite exceeding its radiation design limit by at least a factor of three, the spacecraft survived all the anomalies. The quartz crystal used as the frequency reference for the radio suffered permanent frequency shifts with each Jupiter approach. Galileo's cameras were deactivated on January 17, 2002, after they had sustained irreparable radiation damage. NASA engineers were able to recover the damaged tape recorder electronics, and Galileo continued to return scientific data until (once its fuel supply was nearly depleted) it was deorbited in 2003, performing one last scientific experiment —a measurement of the moon Amalthea's mass as the spacecraft swung by it.>>

[Chris Peterson]

So what, they couldn't design an orbiter to continue to send useful data / pictures for longer than a year? Is it going to run out of gas? Maybe become brain damaged from the radiation belts?

My question still stands, though at a higher level: Why drop it in and burn it up?

Why not? It's a way to get additional scientific data. With all these missions, the probe itself is only one part of the cost- sometimes not even the most expensive component. The missions are designed around some sort of scientific objective, and they are funded accordingly. Even if Juno were left in orbit, there would be no funding for the ground segment- the communications, the facilities, all the members of the science team and their support staff. Under extraordinary circumstances, missions are sometimes extended (that's what happened with the Mars rovers). But there is no guarantee of that. So the mission is designed to collect data from orbit for a year, and then take atmospheric measurements during a planned (and required) destruction phase. And yes, it will run out of gas if left too long, and that is an important factor in setting the time of its destruction, since it is an important aspect of the mission that it not be left dead in orbit.

[tytower1]

Look out Jupiterians here we come ,don't take this as a sign we intend to bomb you , trust us on this !!

[BPCooper]

Last week included one of the few times in history that humanity launched something completely off the Earth, moving away so fast that it will never return.

What were the others?

Every mission sent to land on or orbit another planet is the answer, with the small exception of a couple of sample return missions to date.

The answer to what spacecraft are escaping the solar system (Juno is not in this category of course) are Pioneers 10 & 11, Voyagers 1 & 2, and New Horizons; as well as their upper stages.

[neufer]

Look out Jupiterians [sic] here we come ,don't take this as a sign we intend to bomb you , trust us on this !!

<<A demonym, also referred to as a gentilic, is a name for a resident of a locality. The word demonym comes from the Greek word for "populace" (δῆμος demos) with the suffix for "name" (-onym). A demonym is usually – though not always – derived from the name of the locality; thus, in English, the demonym for the people of Italy is Italian, though the one used for the people of the Netherlands is Dutch.>>

• Code: Select all

  Planet  	Demonym
  ------------------------------------------
  Mercury:  Mercurian, Hermean
  Venus:    Venusian
  Earth:    Earthling, Terran, Terrestrial, Tellurian
  Mars:     Martian
  Jupiter:  Jovian
  Neptune:  Neptunian
  Saturn:   Saturnian
  Uranus:   Uranian

[NoelC]

it is an important aspect of the mission that it not be left dead in orbit.

That's the first I've heard of conscientious space exploration. And I can't immediately think of justification for it. Isn't it really only around the Earth that we have to worry about space junk?

What could a space archaeology salvage mission 10,000 years from now learn from an old research probe?

Or maybe there will be a manned Jupiter exploration mission one day; a ship in need of a few spare parts...

Actually, mission planners thinking that the little specks we send off into space amounting to anything even remotely important beyond the scientific mission - or dangerous in any foreseeable future - is probably just being arrogant. So I suppose a final suicide mission makes as much sense as just stopping transmissions.

-Noel

[trekman]

Im all for space exploration. Ive always believed we will eventually use up all our resources here on earth. We WILL need another home someday, and the only place to look is in space.

We already know that most if not ALL the planets in our Solar System are un- inhabitable dont we? If so why do we keep sending rockets to study them? Why arent we moving past our system and looking elsewhere?

[Chris Peterson]

it is an important aspect of the mission that it not be left dead in orbit.

That's the first I've heard of conscientious space exploration. And I can't immediately think of justification for it. Isn't it really only around the Earth that we have to worry about space junk?

There is a very real concern about biologically contaminating any of the moons- especially Europa. And the gravitational environment around Jupiter is such that any probe in orbit around that planet is likely to eventually collide with one of the inner moons. So not leaving anything dead in orbit is, and has been, part of Jupiter exploration mandates for a while now.

[rstevenson]

That's the first I've heard of conscientious space exploration. And I can't immediately think of justification for it. Isn't it really only around the Earth that we have to worry about space junk?

Hi Noel,

It's not a matter of space junk. Art was being serious (he does that from time to time to throw us off) when he said we musn't take a chance on contaminating Europa. There's a good chance there is life there -- if there is life anywhere in the Solar System outside of Earth, that is. And we must avoid even the slightest possibility of accidental contamination of that life before we get a chance to study it.

Rob

Oops, Chris is faster on the draw.

[Beyond]

Oops, Chris is faster on the draw

Thats because he lives up high in the mountains where theres less gravity to slow him down.

[neufer]

Art was being serious (he does that from time to time to throw us off)....

Serious...no I wouldn't go that far.

I was doing what I always do: contemplating the issue in all of its aspects, tragical, comical, historical, pastoral, pastoral-comical, historical-pastoral, tragical-historical, tragical-comical-historical-pastoral, scene individable, and poem unlimited.

[revloren]

I'm still not clear on the need to avoid contamination of Europa. We have sent many probes to other bodies, including Mars, Venus and Titan. Perhaps those probes went through a complete serilization process? I find it hard to believe that we could guarantee that there were absolutely no bacteria, viruses or other critters on a probe as it leaves our atmosphere. Also wouldn't Jupiter's radiation kill off anylife after a year in orbit?