Voyager-1 at 100 AU!, A space milestone this month Options

[dilo]

While Space simulator tell us today as the 100AU-from-Sun day, Heavens-above site suggest we have to wait tomorrow... (Voyager1 covers 0.010 AU/day):

The official sites still not mention the milestone, let's see in the next hours!

In the meantime, we can start the two weeks long celebrations...

[Phil Stooke]

Party Poopers! Celebrate both occasions...

Phil

[SigurRosFan]

Here's my 100 AU prediction: August 12, 2006, 11:30 UT

[SigurRosFan]

11:25 UT ...

- http://www.heavens-above.com/solar-escape....logne&TZ=CE

[Planet X]

Why is there such a lack of coverage on this important milestone? I mean, I've seen nothing about it on the news, other sites, or even the Voyager homepage!

BTW, Voyager 2 will reach 100 AU in mid-November 2012, while slowpoke Pioneer 11 will take until late-January 2019 to reach 100 AU! Later!

J P

[djellison]

Planetary Radio covered it this week with Ed Stone as the guest

Doug

[dilo]

Thanks for the highlight, Doug!
Ed had the incredible privilege to follow Voyager mission from development stage to Interstella Mission (34 years, till now! ).

Meanwhile, I made these plots based on weekly reports published in the Voyager sites (source: http://voyager.jpl.nasa.gov/mission/weekly...orts/index.htm).

While first one show historic distance and velocity from Sun, second one is the most interesting because reports the propellent and power availability in last 11 years.
If we exclude very last points (which are probably wrong), linear interpolation show that hydrazine, with current consumption rate, should last 45 years on V1 and 50 years on V2.
On the energy side, Voyager-2 has a constant, 6 months advantage over his brother. The negative-exponential power interpolation of last 5 years trend suggest an average half-life time of 47 years (it was slightly shorter in previous years) - I guess this is the product of plutonium decay and termocouple/electronics slow degrade...
Finally, the margin figures are a little bit misterious to me, because the difference between actual power output and this margin isn't constant... anyway, shouldn't be so important for spacecraft life because, fortunately, they can switch off instruments in order to increase that margin.

[ljk4-1]

Very nice charts, Dilo, thanks.

Considering that Voyager 1 visited fewer worlds than Voyager 2 and it
would therefore be assumed that it used less propellant, why does it have
less hydrazine in fact?

[remcook]

I made these plots based on weekly reports published in the Voyager sites

Good to know I'm not the only one nerdy enough to do this

[djellison]

It's only a couple of Kg - it may well be that the trajectory for the initial launches were such that additional payload capacity was available for V2 and thus it was tanked up a little heavier. (Identical LV's on slightly different traj's would suggest slightly different mass budgets perhaps)

Perhaps because V1 was the first one out the gate, the lessons learnt on how to minimise fuel useage were learnt on V1 and carried over to V2.

And it's not hard to imagine one extreme safing event causing a big chunk of fuel useage at some point during a 20+ year mission.

Lots of reasons that could cause the difference.

Doug

[Guest_Analyst_*]

The Voyager 2 launch window has been more demanding for the Titan 3E. Voyager 1 has been the less demanding and only because of this very reason the Centaur upper stage of this launch vehicle was able to compensate for a Titan second stage propellant leak and the resulting underspeed. Voyager 1 needed a pretty high delta v to target for the Saturn and Titan encounters (and occultations) after the Jupiter flyby.

I have been locking for more engineering details abaout Voyager, including TCMs. Never found much.

Analyst

[ljk4-1]

The Guardian had an editorial on the Voyager 1 100 AU anniversary in
its August 8 edition here:

http://www.guardian.co.uk/leaders/story/0,,1839454,00.html

[dilo]

Finally, JPL news reported it!
The date is 3/4 days after what we said based on SpaceSimulator and HeavensAbove...
(thanks to Max site for the highlight).

[dilo]

...and NASA too!

[RNeuhaus]

New Horizonts salutes Voyager.

Though New Horizons will also reach 100 AU, it will never pass Voyager 1, because Voyager was boosted by multiple gravity assists that make its speed faster than New Horizons will travel. Voyager 1 is escaping the solar system at 17 kilometers per second. When New Horizons reaches that same distance 32 years from now, propelled by a single planetary swingby, it will be moving about 13 kilometers per second.

New Horizons will reach 100 AU in December 2038.

Rodolfo