Nobody highlighted this and I didn't find any comment from Nasa/Voyager sites.
On August,11 the intrepid Voyager-1 probe will reach 14.960 billion Km from the Sun, one hundred times the average Earth-Sun distance!
This event will be followed, after 16 days, by the 100AU from Earth reach.
From astrophysical standpoint, first event is the most important but, I think, most people will be emotionally hit from the second one.
So I would like to start a poll on this.
I would rather prefer AU as the reference from Sun. The Earth is no longer as the center of the world which were tought in the older times....
Rodolfo
Dilo,
I understand you use Nasa space calculator but, does the difference goes as 100-1 for Earth distance or do you consider the EXACT position of Earth on August 25th? You know, the difference could be + or - 1 UA depending where's the Earth on its orbit. By the way, August 25th is prety close to celebrate the 17th anniversary of Voyager II fly-by of Neptune.
By the way, if you open up a pool like arrival of Oppy at VC or Eagle, my bets are 100 UA from SUN first
Can you tell us when the round trip signal will need 24 hours?
Climber, using Nasa space SIMulator is pretty easy to know the exact moment of both events, withut additional calculation... moreover, as you can see from following snapshot, Earth will be going farther from Voyager at this epoch, so no risk of "multiple" 100AU events!
Dilo, by then Voyager will already be 50. I thougth they'll expect them to last up to 2025 or may be it was 2015.
http://voyager.jpl.nasa.gov/science/index.html
In about 10 years from now they will start to share power between instruments (now we are around 290W output, like Spirit at Gusev!). Let's hope ups is right (name seems appropriate!)
without a doubt, celebrate 100 AU from the sun
When the Pioneers and Voyagers are 100 light years from Sol, then we'll talk celebration.
If they can just track the Voyagers' radio signal after the probes are no longer
able to power any of their science instruments, how many more years will that
last and what science could we gain from it?
The two Voyager spacecraft have always been special for me. From a scientific, a programmatic and an engineering point of view they stand out.
They explored four planets in detail for the first time (I am a little unfair to Pioneer 10 and 11), and countless moons. They discovered new moons, volcanos on Io and geysers on Triton. The Voyagers carry an almost complete suite of then state of the art instruments found rarely before and after. Today budget pressure leaves you often with only a very limited number of instruments. Look at DAWN, we built the first asteroid orbiter and cut the magnetometer and laser altermeter. Or MER without a weather station.
It has not been easy for the Voyager program in the 1970ies. There were first four much larger probes. Later it was hoped to sent one to Pluto. Not to happen, only two smaller ones, less expensive. Then politics wanted to shut them down after the Saturn encounter. Now this program has been running for 35+ years. A lot of their fathers retired or passed away, they are still working at the final frontier.
Their engineering design included some very clever things, some used for the first time. I am still impressed by the telecom system: X-band primary with 115.2 kbps from Jupiter, 21.6 kbps from Neptune. New Horizons will have 768 bps planned from Pluto, hopefully a little more (maybe twice). Onboard image compression. Important for rapid instrument pointing is the scan platform. Or look at the scheduling difficulties Cassini has between data collection and downlink becuase there is no such platform. Also for the first time: an integrated SRM and hydrazine trusters. And gyros and star trackers still working after 29 years. So they still point to earth and hopefully will for a long time to report entering true interstellar space.
I wish them a long live, always a good link margin. And may the budget last longer than the RTGs.
Analyst
Well said, analist!
Voyager mission is a miracle, from both science and tech standpoint. I deeply admire who conceived, build and managed these probes.
Can you tell more about initial plan to send 4 larger spacecrafts???
Voyager, the grand tour, started as the Thermoelectric Outer Planet Spacecraft (TOPS) in the late 1960ies Because of the long travel time a new computer, the so called Self Test And Repair (STAR) general purpose machine was planned to be used. Different launch strategies were discussed. One was two launches in 1977 to Jupiter-Saturn-Pluto and two in 1979 to Jupiter-Uranus-Neptune. The ideal planetary alingment in the late 1970ies has been identified at Caltech/JPL. The spacecraft were not that much larger (although they required a Titan 3E with 7 segment SRMs for some trajectories), but more sophisticated, designed to suvive 10+ years, and thus more expensive. In the early 1970ies, during the end of Apollo and the birth of the Space Shuttle, the Nixon administration canceled TOPS, the grand tour, for budget reasons (They had a useless war to fight, very much like today.).
Shortly thereafter NASA came up with Mariner Jupiter-Saturn (MJS), a design based on the Mariner spacecraft, being less expensive and more simple. MJS used a lot of the Viking computer and you can see the Mariner heritage if you look at the 10-sided bus. During development MJS involved into an almost new design: 3.7m high gain antenna, X-band primary, radiation hardened parts, RTGs, hydrazine trusters etc. But MJS was planned only explore Jupiter and Saturn within a four year mission. Before launch it was renamed Voyager (The program to develop unmanned Mars landers to be launched on Saturn launch vehicles has also been called Voyager in the 1960ies and later became Viking.). During launch were was the option to send the first launched spacecraft (JSX) to Uranus (X=U), if the other (JST) performed well during its mission including the very important close Titan encounter. We all know it did and Voyager 2 went to Uranus and Neptune. And both are still working.
It is a great story, even long before launch. A good reference is: http://www.amazon.com/gp/product/1588341240/sr=8-1/qid=1154853280/ref=sr_1_1/104-6974456-7058345?ie=UTF8
Analyst
The AIAA journal "Astronautics and Aeronautics" had a major article on TOPS in an issue in the early 70's, before the mission was canceled and re-created as Mariner Jupiter/Saturn, then Voyager. I was P****D when they renamed the vehicles from Mariner 11 and 12 to Voyager 1 and 2. I'm sure it was a NASA HQ public information office stupidity, figuring a #1 would be more interesting than a #11.
Thank you for the infos, Analyst!
No, the Klingons blew P'neer to bits in one of the movies.
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):
Party Poopers! Celebrate both occasions...
Phil
Here's my 100 AU prediction: August 12, 2006, 11:30 UT
11:25 UT ...
- http://www.heavens-above.com/solar-escape.asp?lat=50.933&lng=6.950&alt=46&loc=Cologne&TZ=CE
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
Planetary Radio covered it this week with Ed Stone as the guest
Doug
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-reports/index.htm).
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?
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
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
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
Finally, JPL news http://www.jpl.nasa.gov/news/features.cfm?feature=1150 it!
The date is 3/4 days after what we said based on SpaceSimulator and HeavensAbove...
(thanks to http://spacespin.org/ for the highlight).
...and http://www.nasa.gov/mission_pages/voyager/voyagerf-20060815.html too!
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
Thanks, Rodolfo.
Let's hope NH will be operative 32 years for now, in order to check variations in the termination shock...
That is a very late answer for V1 (and quite early for V2) : I'll propose neither 100 AU from the Sun, nor 100 AU from the Earth, but 100 AU from the Solar System center of gravity. After all, the Voyager's trajectories are simpler when expressed from the center of gravity, now that they are so far away from the major planets.
In practice, this will seldom change the date by more than a fraction of one day (the maximum effect from Jupiter is about half a day).
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