Project Lyra: Sending a Spacecraft to 1I/’Oumuamua (formerly A/2017 U1), the Interstellar Asteroid

Now that we have determined that the object now known as 1I/’Oumuamua is indeed interstellar in origin, is there any way we could launch a mission to study it? The study below, written by key players in the Initiative for Interstellar Studies (i4is), examines the possibilities. Andreas Hein is Executive as well as Technical Director of i4is, while Nikolas Perakis, a graduate student at the Technical University of Munich, serves as Deputy Technical director. Kelvin Long is president and co-founder of i4is; Adam Crowl, a familiar figure to Centauri Dreams readers, is active in its technical programs. Physicist and radio astronomer Marshall Eubanks is the founder of Asteroid Initiatives; systems engineer Robert Kennedy is president of i4is-US and general chair of the Asilomar Microcomputer Workshop. Propulsion scientist Richard Osborne serves as i4is Director of Technology & Strategic Foresight. Their plan for 1I/’Oumuamua follows. For a more in-depth look, view the paper just released on arXiv at https://arxiv.org/abs/1711.03155.

by Andreas M. Hein, Nikolas Perakis, Kelvin Long, Adam Crowl, Robert G. Kennedy III, Marshall Eubanks and Richard Osborne

A mysterious visitor from our galaxy has entered our solar system. On October 19th 2017, the University of Hawaii’s Pan-STARRS 1 telescope on Haleakala discovered a fast-moving object near the Earth, initially named A/2017 U1, but now designated as 1I/’Oumuamua [1]. This object was found to be not bound to the solar system, with a velocity at infinity of ~26 km/s and an incoming radiant (direction of motion) near the solar apex in the constellation Lyra [2]. Due to the non-observation of a tail in the proximity of the Sun, the object does not seem to be a comet but an asteroid. More recent observations from the Palomar Observatory indicate that the object is reddish, similar to Kuiper belt objects [3]. This is a sign of space weathering. Its orbital features have been analyzed by [2,4].

When will such an object visit us again? In 10 years, 100 years, 1000? We do not know. This could be the only opportunity in a lifetime, or even in a 100 lifetimes to observe an interstellar visitor close by. As 1I/‘Oumuamua is the nearest macroscopic sample of interstellar material, likely with an isotopic signature distinct from any other object in our solar system, the scientific returns from sampling the object are hard to overstate. Detailed study of interstellar materials at interstellar distances are likely decades away, even if Breakthrough Initiatives’ Project Starshot, for example, is vigorously pursued. Hence, an interesting question is if there is a way to exploit this unique opportunity by sending a spacecraft to 1I/’Oumuamua to make observations at close range.

To answer these questions, the Initiative for Interstellar Studies, i4is, has announced Project Lyra on the 30th of October. The goal of the project is to assess the feasibility of a mission to 1I/’Oumuamua using current and near-term technology and to propose mission concepts for achieving a fly-by or rendezvous. The challenge is formidable: 1I/’Oumuamua has a hyperbolic excess velocity of 26 km/s, which translates to a velocity of 5.5 AU/year. It will be beyond Saturn’s orbit within two years. This is much faster than any object humanity has ever launched into space. Compare this to Voyager 1, the fastest object humanity has ever built, which has a hyperbolic excess velocity of 16.6 km/s. As 1I/’Oumuamua is already on its way of leaving our solar system, any spacecraft launched in the future needs to chase it. However, besides the scientific interest of getting data back from the object, the challenge to reach the object could stretch the current technological envelope of space exploration. Hence, Project Lyra is not only interesting from a scientific point of view but also in terms of the technological challenge it presents.

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Figure 1: Logo for the i4is initiative Project Lyra

After days of intense work, we are now able to present some preliminary results for reaching the object within a timeframe of a few decades.

Trajectory analysis

Given the hyperbolic excess velocity and its inclination with respect to the solar system ecliptic, the first question to answer is the required velocity increment (DeltaV) to reach the object, a key parameter for designing the propulsion system. Obviously, a slower spacecraft will reach the object later than a faster spacecraft, leading to a trade-off between trip duration and required DeltaV. Furthermore, the earlier the spacecraft is launched, the shorter the trip duration as the object’s distance increases with time. However, a launch date within the next 5 years is likely to be unrealistic, and even 10 years could be challenging, in case new technologies need to be developed. Hence, a third basic trade-off is between launch date and trip time / characteristic energy C3. The characteristic energy is the square of the hyperbolic excess velocity, which can be understood as is the velocity at infinity with respect to the Sun. Nikolaos Perakis (i4is) has captured these trade-offs in Figure 2. The figure plots the characteristic energy for the launch with respect to mission duration and launch date. An impulsive propulsion system with a sufficiently short thrust duration is assumed. No planetary or solar fly-by is assumed, only a direct launch towards the object. The deformations of the velocity curves is due to the Earth’s orbit around the Sun, which results in a more or less favorable position for a launch towards the object. It can be seen that a minimum