Project Lyra: A Probe to ʻOumuamua

The first verified Interstellar Visitor to our Solar System is the object 1I/2017 U1 (aka ʻOumuamua), which is a spindle shaped body that flew in from the direction of the constellation Lyra, came closer to the Sun than Mercury, shot past Earth at a distance of 0.16 AU, then receded rapidly away. Ultimately 1I/2017 U1 will leave with a hyperbolic excess of over 26 km/s.

The Initiative For Interstellar Studies, of which I am a part, was naturally intrigued by the possibility of sending a probe to an Interstellar Object using near-term technologies on a merely decadal mission, rather than millennial. The resulting effort by a great team produced this preprint:

Project Lyra: Sending a Spacecraft to 1I/ʻOumuamua (former A/2017 U1), the Interstellar Asteroid

…which is a starting point for further research work on the options available. Technology Review even picked it as one of the best arXiv Preprints of the Week ending 17 November 2017.

My initial thoughts, for a very rapid mission preparation, would be a clone of the New Horizons vehicle, which successfully visited Pluto/Charon and is heading for a new encounter in 2019, but launched into a Jupiter gravity-assist that would throw it towards the Sun. Why? To maximise the boost, via the Oberth (or “Gravity Well”) Maneuver. I assumed a high-thrust chemical rocket, based on the JPL work for sending probes into the Local Interstellar Medium.

Other options, with lower technology readiness levels (TRLs), would rely on Solar Thermal Boosters, Solar Electric Propulsion, E-Sails, Mag-Sails, and so forth. They’re all good, but 1I/2017 U1 is *rapidly* leaving the Solar System behind. A decade delay in launching means the intercept is out in the “Great Big Dark” between the stars, thus complicating navigation, antenna pointing, and likely science return.

Even if we don’t launch after this particular interstellar vagabond, all our best theories of planet formation suggest immense numbers of such objects are passing by. We’ve only *just* become able to see them, thanks to powerful all-sky surveys that have gone online in recent years.

5 Replies to “Project Lyra: A Probe to ʻOumuamua”

  1. Solar-Electric Ion for sure.
    It has the high Isp and the kW/kg necessary to reach Oumuamua for a flyby. If it dedicates a lot of dry mass to solar panels, it might burn most of its propellant near Earth and the Sun, for a better acceleration.

    You mention 26km/s exit velocity for the asteroid. What do you estimate is the deltaV necessary for a mission to reach it?

  2. Hi Matter Beam
    Cool name BTW. Delta-vee wise the probe needs a hyperbolic excess (h-x) more than ?Oumuamua’s 26.3 km/s. The longer the lag-time before launch, the higher the needed h-x. Say we launch it with 2 AU/year extra (h-x ~ 36 km/s), then intercept would take at least ~25 years if ?Oumuamua is 50 AU away at launch.

    To maximise SEP we need it to start closer to the Sun (max power) and have sufficient thrust to burn at greater than local Solar gravity the whole way. Plus there’s the additional delta-vee to match the inclination of ?Oumuamua. A stern-chasing orbit, which mirrors ?Oumuamua’s orbit as much as possible except speed, would maximise encounter time, especially if we’re firing a sampling laser or impactor slug at it during the terminal encounter.

    I’m still grinding through the maths and trying to do this analysis in Excel. Copernicus or some similar NASA software would help. As institutions can request it I’m going to put a request in under I4IS’s auspices. Can’t hurt to ask.
    https://www.nasa.gov/centers/johnson/copernicus/index.html

  3. What would it take to finish up a SNAP reactor with a Dawn ion drive (extra xenon fuel) and place that atop Falcon Heavy?

    Over time, could it catch up and dock

    1. Not sure that’s enough Power-to-Mass ratio to achieve the mission. But there’s merit to the general idea. JPL are working on a lithium propellant ion-drive and NASA’s Kilopower mini-nuclear reactors would be perfect for the job. The problem with xenon is its availability – only tons per year are extracted.

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