Interferometric Measurement of Acceleration at Relativistic Speeds

Christian, Pierre; Loeb, Abraham

doi:10.3847/2041-8213/834/2/l20

Cited by 17 publications

(32 citation statements)

References 14 publications

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“…A laser sending the proper time of the sail to Earth would allow distance and speed measurements through the relativistic Doppler effect. Measurements of gravitational perturbations (Christian & Loeb 2017;Witten 2020) under consideration of dust and gas drag as well as magnetic forces exerted from the interstellar medium (Hoang & Loeb 2020) could also be used to search for the suspected Planet Nine in the outskirts of the solar system. Its expected orbital semimajor axis is between about 380 AU and 980 AU .…”

Section: Follow-up Monitoring Of the Sailmentioning

confidence: 99%

Low-cost precursor of an interstellar mission

Heller

Anglada-Escudé

Hippke

et al. 2020

A&A

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The solar photon pressure provides a viable source of thrust for spacecraft in the solar system. Theoretically it could also enable interstellar missions, but an extremely small mass per cross section area is required to overcome the solar gravity. We identify aerographite, a synthetic carbon-based foam with a density of 0.18 kg m−3 (15 000 times more lightweight than aluminum) as a versatile material for highly efficient propulsion with sunlight. A hollow aerographite sphere with a shell thickness ϵshl = 1 mm could go interstellar upon submission to solar radiation in interplanetary space. Upon launch at 1 AU from the Sun, an aerographite shell with ϵshl = 0.5 mm arrives at the orbit of Mars in 60 d and at Pluto’s orbit in 4.3 yr. Release of an aerographite hollow sphere, whose shell is 1 μm thick, at 0.04 AU (the closest approach of the Parker Solar Probe) results in an escape speed of nearly 6900 km s−1 and 185 yr of travel to the distance of our nearest star, Proxima Centauri. The infrared signature of a meter-sized aerographite sail could be observed with JWST up to 2 AU from the Sun, beyond the orbit of Mars. An aerographite hollow sphere, whose shell is 100 μm thick, of 1 m (5 m) radius weighs 230 mg (5.7 g) and has a 2.2 g (55 g) mass margin to allow interstellar escape. The payload margin is ten times the mass of the spacecraft, whereas the payload on chemical interstellar rockets is typically a thousandth of the weight of the rocket. Using 1 g (10 g) of this margin (e.g., for miniature communication technology with Earth), it would reach the orbit of Pluto 4.7 yr (2.8 yr) after interplanetary launch at 1 AU. Simplistic communication would enable studies of the interplanetary medium and a search for the suspected Planet Nine, and would serve as a precursor mission to α Centauri. We estimate prototype developments costs of 1 million USD, a price of 1000 USD per sail, and a total of < 10 million USD including launch for a piggyback concept with an interplanetary mission.

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Section: Follow-up Monitoring Of the Sailmentioning

confidence: 99%

Low-cost precursor of an interstellar mission

Heller

Anglada-Escudé

Hippke

et al. 2020

A&A

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“…The Breakthrough Starshot initiative, whose advisory committee I chair, 2 aims to launch a lightweight spacecraft to a fifth of the speed of light using a laser beam pushing on a sail (Fig. 2), [3][4][5][6] so that the camera attached to the sail could reach nearby habitable planets like Proxima b within our lifetimes. The pursuit of this concept became feasible owing to recent advances in laser technology and the miniaturisation of electronics.…”

Section: Ismentioning

confidence: 99%

Searching for life among the stars

Crockett¹

2017

Knowable Mag.

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“…It has already been pointed out that such long-distance missions could be used to constrain modified gravity theories (Christian & Loeb 2017). Those authors considered a spacecraft travelling at 0.2 c, where c is the speed of light in vacuum.…”

Section: Introductionmentioning

confidence: 99%

Testing gravity with interstellar precursor missions

Banik

Kroupa

2019

Monthly Notices of the Royal Astronomical Society

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We consider how the trajectory of an interstellar precursor mission would be affected by the gravity of the Sun in Newtonian and Milgromian dynamics (MOND). The Solar gravity is ≈ 50% stronger in MOND beyond a distance of ≈ 7000 astronomical units, the MOND radius of the Sun. A spacecraft travelling at 0.01 c reaches this distance after 11.1 years. We show that the extra gravity in MOND causes an anomalous deceleration that reduces its radial velocity by ≈ 3 cm/s and the twoway light travel time from the inner Solar System by ≈ 0.1 seconds after 20 years. A distinctive signature of MOND is that the gravity from the Sun is not directly towards it. This is due to the non-linear nature of MOND and the external gravitational field from the rest of the Galaxy, which we self-consistently include in our calculations. As a result, the sky position of the spacecraft would deviate by up to 0.2 mas over 20 years. This deviation is always in the plane containing the spacecraft trajectory and the direction towards the Galactic Centre. By launching spacecraft in different directions, it is possible to test the characteristic pattern of angular deviations expected in MOND. This would minimize the chance that any detected anomalies are caused by other processes like drag from the interstellar medium. Such confounding factors could also be mitigated using an onboard accelerometer to measure non-gravitational forces. We briefly discuss how the gravity theories could be conclusively distinguished using a Cavendish-style active gravitational experiment beyond the Sun's MOND radius.

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Interferometric Measurement of Acceleration at Relativistic Speeds

Cited by 17 publications

References 14 publications

Low-cost precursor of an interstellar mission

Low-cost precursor of an interstellar mission

Searching for life among the stars

Testing gravity with interstellar precursor missions

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