Do it again, but harder!
Project Lyra: A feasibility study for a mission to the interstellar asteroid ‘Oumuamua
For the first option, we use a mission concept that has been previously proposed by a Keck Institute for Space Studies report for exploring the interstellar medium. It is essentially a rollercoaster ride The spacecraft is first sent on a trajectory out of the Earth’s gravitational field using a large rocket, for example the Falcon Heavy, Space Launch System, or the Big Falcon Rocket. The spacecraft is accelerated to such high velocities that it is not only thrown out of the Earth’s gravity field but has enough energy to fly out to Jupiter. At Jupiter, the planet’s gravity decelerates the spacecraft with respect to the Sun. ... our spacecraft has been decelerated so much by exploiting Jupiter’s gravity field that it is now on a trajectory that it is falling towards the Sun in an almost straight line, an extreme roller coaster ride, although it takes over a year to fall. Of course the spacecraft will not fall into the Sun but would move away from the Sun once it has passed its closest point to the Sun. The spacecraft gets very close to the Sun, about 3 solar radii or about 1.5 million km. At such a distance, the solar radiation is about 20,000 times higher than what you receive during a sunny day. Converted to Watts per square meters, the power per area is about 15 MW / m². This is higher than the power per area inside a fusion reactor. To avoid that the spacecraft melts away, a heat shield is used which is similar to the heat shield of the NASA Solar Orbiter mission, which fill fly close to similar distances to the Sun and is currently undergoing testing. Now, at the closest point to the Sun, the spacecraft ignites a solid propellant engine it has been carrying all its way. In orbital mechanics, you get the biggest “bang for the buck” for a rocket engine, if you ignite it at the closest point to the central body. Hence, the whole idea of falling so closely to the Sun is to ignite the engine at the closest point of approach and then to be propelled away from the Sun with the maximum “bang”. The spacecraft flies away from the Sun at the incredible speed of about 370 km/s. At this speed you would get from London to New York in 15 seconds. Note that this is the speed you would need for a mission duration to ‘Oumaumua in 8 years and a launch in 2021. The spacecraft will have a velocity at infinity of 55 km/s and is therefore much faster than ‘Oumuamua with 26 km/s. The spacecraft would fly pass ‘Oumuamua in 2029, taking images using a telescope at a distance from the Sun of 69 Astronomical Units (Earth-Sun distances). At this point ‘Oumaumua will be a black object in front of the blackness of space. Where the human eye would fail, a telescope and other instruments will suck in the electromagnetic waves that are nevertheless emitted by ‘Oumuamua. The data will then be sent back to Earth with an antenna powered by nuclear radioisotopic generators, a chunk of Plutonium whose heat is transformed into electricity. Finally, the data is transformed into images. What will we see?
The Lyra paper is Project Lyra: Sending a Spacecraft to 1I/'Oumuamua (former A/2017 U1), the Interstellar Asteroid, Andreas M Hein, Nikolaos Perakis, Kelvin F Long, Adam Crowl, Marshall Eubanks, Robert G Kennedy III, Richard Osborne arxiv.org/abs/1711.03155