“We don’t know when Voyager 2 will cross into interstellar space”

By A Rahim Khan – 

Pique‘s exclusive interview with Project Manager for the Voyager missions, Suzanne Dodd

Interstellar

As lone pilgrims, offered to the stars, the spacecrafts Voyager 1 and 2 chart their way through space unknown, hymnals to an interstellar beat. Their passage has been through the dense nether of space, travelling to a destination they may never meet.  Their progress has been inexorably forwards, bidding farewell to an Earth long since in their pasts, addressing, along the way, the planets of the Solar System  and hailing, with a cheer seconded at home, the very outer limits of our space and the beginnings of someone else’s.

The stories of Voyager 1 and 2 have been nearly 40 years in the making, back to the early 70s when the US space agency NASA endeavored to conduct a ‘grand tour’ of our Solar System, launching the twin space probes in 1977.

Since then the space craft have been making their way through the Solar System, each conducting flybys of the planets in our neighborhood, observing and reporting, quietly seeking an egress. The distances covered in this crossing have literally been astronomical, but it was not until September 12, 2013 that a milestone had been achieved. Voyager-1, all 800kg of it, had officially crossed the ‘heliopause’ (where solar winds cease) marking the ends of the empire of the sun and the beginning of the space between stars, interstellar.(Note: While the official announcement was made in 2013, Voyager-1 had actually crossed the heliopause in August 2012,  scientists in the meanwhile confirming and reconfirming the data)

Voyager-1 has travelled an ineffable 19,326,519,918km (at least as of this article) making it the farthest manmade object from Earth and the first in human history to leave the Solar System and breach interstellar space. Not resting on its laurels, the spacecraft will continue on its path, going further than before, until its batteries run out somewhere in the next couple of decades. Its sister, Voyager-2 is on a similarly staggering journey and while unclear as to whether or not it too has left the Solar System, both it and its sibling are destined to forever be pilgrims, devoted to space.

In an exclusive interview with Pique, Project Manager for the Voyager missions, Suzanne Dodd, spoke about the spacecraft’s achievements and their legacy.

Launching back in the 70s, and the many years before that preparing for the mission, did you ever think Voyager -1 would achieve the milestone that it has? Were there ever any moments of doubt?

We had always hoped and planned for the possibility of reaching interstellar space.  Some of the instruments have operating modes designed for taking data in the heliosphere and local interstellar medium.  During the planetary encounters, there were anomalies that occurred that potentially jeopardized the mission’s survival, but thankfully nothing mission-ending has occurred.

There must be a certain amount of pride with having put the most distant human objects into space and of course the first into interstellar space – could you describe this?

I think everyone who has worked on the Voyager mission, and that is close to 1,000 people during the pre-launch development and 37 years of operation, is proud of what Voyager has accomplished and proud of what we know it is still capable of accomplishing.  It’s like watching your child grow up and become a very successful adult.

Both Voyagers have now been operating for close to 40 years in the harshness of space and are expected to continue for decades more – that in itself is quite an achievement, what would you ascribe this to?

The Voyager spacecraft were built very robustly and had a full complement of testing before launch.  The mission plan was laid out to achieve the major science objectives while preserving the spacecraft lifetime.  We also have had some luck along the way.

While Voyager – 1 had been on the cusp of interstellar space for some time now, the Voyager team took its time to announce this, what kind of data were you waiting on to confirm this?

The science discovery process works through a consensus of agreement among experts. The interstellar data was debated among the science team members for several months before agreement was reached that Voyager 1 had crossed into interstellar space.

In an interview, Dr.  Ed Stone (former project scientist on the mission) compared Voyager-1’s milestone with other historical events such as Neil Armstrong’s first step on the moon. While this particular event has figured greatly in the public’s imagination do you think Voyager-1’s achievement registered just as much? Do you think in the coming years it will be as revered as the first man on the moon?

I think there is a connection between Voyager entering interstellar space and the human spirit to explore beyond what we can see and touch.  Voyager will be remembered as the first man-made object to cross the boundary of our sun’s plasma bubble and journey across interstellar space.

When is Voyager -2 expected to leave the Solar System?

We don’t know when Voyager 2 will cross into interstellar space.  It could be as soon as a year or as long as a decade.

Both missions have contributed a great deal to our knowledge and understanding of the Solar System and space itself, besides their milestones, what do you think the probes most important discoveries have been?

Voyager made new discoveries at each of the planets it flew by, and it continues to make discoveries today on the nature of the heliosphere and interstellar space. One of the most oft-mentioned discovery is the first images of a volcano erupting on another body: Jupiter’s moon Io.

It is expected that both Voyager 1 and 2 will continue to send back data for another decade or so, what can we expect to learn from their journeys?

I expect Voyager 2 to cross into interstellar space before we run out of power in 2025.  Voyager 1 will continue its new mission chapter on discovering the nature of interstellar space.

Can we expect similar missions like this from NASA in the future?

I hope that NASA will continue to explore the outer planets and also send another spacecraft to interstellar space. The distances are very far and it takes many years to travel to Uranus, Neptune, and beyond.  Thus, is takes a long-term commitment to launch and operate a mission covering similar distances as done by Voyager.

 The writer is a journalist based in Islamabad