# Shortest time to place a probe further than Voyager 1?

Based on today's technology (requiring no new engineering hurdles to be solved), could a new interstellar space probe overtake Voyager 1's distance? It doesn't need to go in the same direction, but just achieve a further distance from Earth than Voyager 1? I assume the answer is yes, and if so, with today's technology how quickly could this be accomplished?

Ultimately, I'm curious if Voyager 1 is destined to be the furthest man-made object from Earth in my lifetime.

• Well it's not been tried but all the technology exists for the "breakthrough starshot" project. Look it up – Dragongeek Dec 5 '17 at 21:54
• A very simple estimate: Voyager 1 is travelling 40 years now, it is 21 billion km away now and each year the distance increases by 540 million km. If we start a probe now that should reach equal distance in 40 years, the necessary speed is about 1 billion km per year. I assumed constant speed and linear path. To double the speed would be very difficult and expensive. – Uwe Dec 5 '17 at 21:54
• I don't think so... unless this answer is wrong. – Ryan Sandridge Dec 5 '17 at 22:03
• @Dragongeek Very little of the required technology for Breakthrough Starshot exists. All the theory exists but that's not the same thing. – Russell Borogove Dec 5 '17 at 22:12
• Very relevant what-if.xkcd.com/38 (answer is 100 to 200 years) – Antzi Dec 6 '17 at 5:22

Voyager 1 received gravitational assists increasing its velocity from both Jupiter and Saturn.

Opportunities for such a Jupiter-Saturn trajectory occur about every 20 years, so we don't have to wait too long to launch, at least; in order to outperform Voyager we merely need to launch a probe of about the same total mass as Voyager, at the same initial velocity, with the same gravity-assist parameters, but including a propulsion system in place of the 105kg of scientific instruments carried by the earlier probe. An ion engine would give the most ∆v for the mass; something like an NSTAR thruster of 25kg plus 80kg of Xenon propellant, on a total spacecraft mass of 773 kg, firing for about a year, would yield an additional 3km/sec above Voyager's speed. (Power would be a bit of a problem; Voyager produced only ~430W from its radiothermal generators, while NSTAR wants 2100W for maximum efficiency, but we can handwave this away by assuming a smaller thruster operating for a longer period of time.)

Improvements in computer and other technologies over the last 40 years should make it possible to shave off additional mass from the probe, of course. Those mass savings could pay for additional propellant on the probe.

The Titan IIIE booster that launched Voyager is no longer in service; the Atlas V 551 configuration that launched New Horizons slightly outperforms the Titan in mass-to-LEO, so I assume it could serve this role.

Voyager 1 does have a substantial head start, however, so it could take something like 200 years for this speedy little probe to outdistance it.

A larger booster -- Delta IV Heavy, Falcon Heavy, SLS, or SpaceX's future rockets -- could of course lift a very powerful upper stage that could give the probe another substantial boost, perhaps cutting the outdistancing time in half or further.

So, with no major technological advances, I estimate it should be no more than 20 years from budget approval to launch, and 100-200 years from launch to outdistancing depending on the budget.

APL is studying an interstellar mission with a speed goal of 20 AU/year, 5 times faster than the Voyagers. This is feasible with minimal development of current technology.

At that speed, it'd need about 9 years to overtake the Voyagers.

• As I read that study, 20 AU/yr is what they'd lie. 8 AU/yr is what they can see how to get (with an unpowered gravity assist at Jupiter and a powered gravity-well maneuver at the Sun). – Steve Linton Dec 11 '18 at 12:03
• Yes, there are some uncertainties in the study. The heat shielding has to be better than that of the Parker solar probe, and you'd need a large upper stage that can withstand high temperatures. On NasaSpaceflight someone mentioned there's a STAR 92 stage which has the performance needed, but this hasn't been qualified for use near the Sun. Hence 'minimal development of current technology'. – Hobbes Dec 11 '18 at 12:22

We know how to build mass drivers (basically, a very high power maglev train that doesn't stop accelerating until it runs out of track.)

Long ago I saw a 100g version on TV. There's basically zero issues with making it longer until the surface curvature of the body you mounted it on matters.

Thus we could build such a system on the moon and launch something that can overtake Voyager. There's nothing we don't know how to do but it's a pretty massive engineering project. (However, unless it becomes obsolete before being built I think it's something that will be done. While using it to overtake Voyager would be a waste it can boost payloads elsewhere in the solar system.)

• The question was about todays technology. Your answer assumes a lot of things that haven't been done yet. – DarkDust Dec 6 '17 at 8:05
• @DarkDust Things we haven't built, not things we don't know how to build. – Loren Pechtel Dec 6 '17 at 17:53
• At this level of future engineering (fairly detailed studies exist, but no one has built anything), project Orion is also possible. Since it's for an unmanned probe, it gets quite a lot simpler -- basically you just built very tough probe and then nuke it repeatedly on the side you want it to move away from. – Steve Linton Dec 11 '18 at 14:23