Project Lyra develops concepts for reaching interstellar objects such as 1I / 'Oumuamua and 2I / Borisov with a spacecraft, based on near-term technologies. But what is an interstellar object?
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. It is now designated as 1I/’Oumuamua. This object was found to be not bound to the solar system. It has a velocity at infinity of ~26 km/s and an incoming radiant (direction of motion) near the solar apex in the constellation Lyra. 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. This is a sign of space weathering.
When will such an object visit us again? End of 2019, a second interstellar object, 2I/Borisov was discovered, which is a comet. As 1I/‘Oumuamua and 2I/Borisov are the nearest macroscopic samples of interstellar material, 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, announced Project Lyra on the 30th October 2017. The goal of the project is to assess the feasibility of a mission to 1I/’Oumuamua, 2I/Borisov and other potential interstellar objects, 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. The challenge to reach the object could stretch the current technological envelope of space exploration.
After days of intense work, we have published some preliminary results on the 8th November 2017 for reaching the object within a timeframe of a few decades. The paper was published on arXiv. Subsequently, our arXiv paper created a surge of media articles, which can be found below.
A revised version of the paper "Project Lyra: Sending a spacecraft to 1I/’Oumuamua (former A/2017 U1), the interstellar asteroid" has been accepted by the journal Acta Astronautica and has been published on the 7th of January 2019.
In the paper, we demonstrate that missions to 'Oumuamua are feasible with current and near-term technologies (Falcon Heavy or Space Launch System launcher, solid rocket motors, and Parker Solar probe heat shield), with an optimal launch date in 2021. However, this launch date would be too soon for developing a dedicated spacecraft, something that usually takes 5 to 10 years for an interplanetary mission.
Hence, in January / February 2019, our team has worked on potential missions after 2024, leaving enough time for spacecraft development. The results have been published on arXiv on the 14th of February. In this paper, titled "Project Lyra: Catching 1I/'Oumuamua - Mission Opportunities After 2024", we show that missions to 'Oumuamua are possible with current and near-term technologies much later than 2021, with opportunities coming up in 2030, 2033, and even later dates. Trip times are 17 and 16 years, respectively, with arrival dates in 2047 and 2049.
A third paper, "Sending a Spacecraft to Interstellar Comet C/2019 Q4 (Borisov)" has been published on the 13th of September 2019 on arXiv, about two weeks after the discovery of 2I/Borisov. An extended version of the paper has been published in the peer-reviewed journal Acta Astronautica in 2021.
We conclude that a mission to 'Oumuamua and Borisov are feasible, not only technologically, but also from a spacecraft development perspective.
Based on the white papers, a peer-reviewed journal paper was published in Advances in Space Research in 2021, exploring a broad range of mission scenarios to various types of interstellar objects.
A further peer-reviewed journal paper explores the use of nuclear thermal propulsion and an additional draft paper the use of laser sails, based on a prototype Breakthrough Starshot architecture. Both technologies would enable unprecedented missions (nuclear: sample return; laser: missions taking only months) to 'Oumuamua even decades into the future.
FAQ: Frequently Asked Questions
Q: Isn't 'Oumuamua already too far away to be chased down?
A: We show in multiple peer-reviewed journal papers (paper1, paper2, paper3) that it is possible to chase down 'Oumuamua even if the spacecraft is launched decades into the future. 'Oumuamua travels at about 26 km/s in interstellar space. The Voyager probes travel at about 17 km/s. However, it is widely known in the space community that with a combination of chemical propulsion and specific gravity assist maneuvers, velocities over 70 km/s can be achieved with existing or near-term technologies. At 70 km/s, the spacecraft will take over 'Oumuamua, as it is much faster than the object.
Q: Isn't 'Oumaumua already too faint and its position too uncertain to be intercepted?
A: We have determined that despite its positional uncertainty, it is feasible to observe 'Oumuamua from a spacecraft. We have studied the viability of this in the peer-reviewed 'Advances in Space Research' paper (Section 3.1). We have solutions for the orbit of 1I, including for its non-gravitational accelerations. Using the uncertainty in all of those parameters, we get that the uncertainty in 1I's position in the outer solar system will be a substantial fraction of a lunar distance, which is a large, but not unsurmountable, position uncertainty. We show that the same LORI telescope used for the New Horizons spacecraft to flyby Pluto can also be used to detect 'Oumuamua, given the positional uncertainty and low brightness due to its great distance from the sun.
Thus, we do not have to wait for the next ISO, we can successfully send a mission to intercept and observe 'Oumuamua. In so doing we can uncover its secrets which hitherto have been the subject of speculation and much scientific discourse. We have the technology to answer these questions.
Q: But does the spacecraft not burn up when it gets so close to the Sun for the Solar Oberth Maneuver?
A: We have shown in peer-reviewed publications that the distance to the Sun for the maneuver is similar to those for the Parker Solar Probe (~10 solar radii) and the same heatshield material can be used as on the probe. The main difference is the size of the shield but a similar heatshield is already existing and in use. For those who still think that this maneuver is too risky, we have recently published a paper proposing a mission which does not rely on a Solar Oberth Maneuver and can still reach 'Oumuamua at the same mission duration.
Q: Shouldn't we just wait for the next 'Oumuamua-like object?
A: We simply do not know how common 'Oumuamua-like objects are. Due to the absence of data, all current estimates have large uncertainties associated to them. There is a risk that we will miss a truly unique object.
Q: But there is a Harvard professor who says it is not possible to fly to 'Oumuamua any more.
A: Prof. Loeb is an accomplished scientist with an impressive track-record. However, he is not an expert in space mission design. We have shown in multiple peer-reviewed journal papers (paper1, paper2, paper3), reviewed by experts from the space community and published in the best space journals, that it is possible to chase down 'Oumuamua even if the spacecraft is launched decades in the future. Prof. Loeb is also the Chairman of the Breakthrough Starshot Advisory Board. Our analysis shows that with a prototype Starshot laser beaming infrastructure, 'Oumuamua can be easily chased down decades into the future. We have also shown that tiny gram-scale spacecraft can detect Oumuamua despite its faintness. Hence, the claim that 'Oumuamua cannot be reached is factually wrong.
Q: Anyway, the mission would cost too much!
A: Our research has shown that spacecraft the size of the New Horizon probe can accomplish the mission to 'Oumuamua. The New Horizons mission has cost about 780 million $. This sounds like a lot but it is actually cheap for a deep space mission. Cassini Huygens has cost 3.26 billion $, for example. However, due to the extraordinary nature of 'Oumuamua, the discoveries we would make will be truly disruptive in any case.
Q: Who will pay for such a misson?
A: This is still an open question, as ideas for missions have to go through
a rigorous selection process if a space agency would pay for it. A precondition is that the scientific community backs such a mission. If sufficient backing exists, the mission would enter the selection process. We are currently working on generating traction within the scientific community for such a mission. While a dedicated mission to 'Oumuamua has not yet gone beyond a feasibility analysis, the Comet Interceptor mission of the European Space Agency has already incorporated a mission objective on reaching an interstellar object, which by chance would enter our solar system at the right moment. It would intercept such an object in case it does not find an adequate long-period comet to explore during its nominal mission duration.
Project Lyra Publications
Hein, A.M., Eubanks, T.M., Hibberd, A., Fries, D., Schneider, J., Lingam, M., Kennedy, R., Perakis, N., Dachwald, B. and Kervella, P., 2020. Interstellar Now! Missions to and Sample Returns from Nearby Interstellar Objects. Advances in Space Research
Volume 69, Issue 1, 1 January 2022, Pages 402-414
Hein, A.M., Perakis, N., Eubanks, T.M., Hibberd, A., Crowl, A., Hayward, K., Kennedy III, R.G. and Osborne, R., 2019. Project Lyra: Sending a spacecraft to 1I/’Oumuamua (former A/2017 U1), the interstellar asteroid. Acta Astronautica, Volume 161, August 2019, Pages 552-561.