The ALFA medium explorer mission

Jones, Dayton L.; Allen, R. J.; Basart, J. P.; Bastian, T.; Blume, W.; Bougeret, J. L.; Dennison, B.; Desch, M. D.; Dwarakanath, K. S.; Erickson, W. C.; Farrell, W. M.; Finley, David G.; Gopalswamy, Ν.; Howard, R.; Kaiser, M. L.; Kassim, N. E.; Kuiper, T. B. H.; MacDowall, R. J.; Mahoney, Michael J.; Perley, R. A.; Preston, R. A.; Reiner, M. J.; Rodriguez, P.; Stone, R. G.; Unwin, S. C.; Weiler, K. W.; Woan, G.; Woo, Richard

doi:10.1016/s0273-1177(99)01204-1

Cited by 17 publications

(14 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The successful single-satellite RAE missions motivated the first space-based array proposal to NASA i.e., the Low Frequency Space Array (LFSA) [76]. Another notable NASA funded study in this regard was the ALFA concept, which proposed an array of 10 − 16 satellites in a distant retrograde orbit [35]. More recently, two ESA funded studies namely FIRST [12] and DARIS [15] investigated passive-formation flying missions for space-based satellite arrays (see Table 1).…”

Section: Previous Studiesmentioning

confidence: 99%

Space-based aperture array for ultra-long wavelength radio astronomy

et al. 2015

View full text Add to dashboard Cite

The past decade has seen the advent of various radio astronomy arrays, particularly for low-frequency observations below 100 MHz. These developments have been primarily driven by interesting and fundamental scientific questions, such as studying the dark ages and epoch of re-ionization, by detecting the highly redshifted 21 cm line emission. However, Earth-based radio astronomy observations at frequencies below 30 MHz are severely restricted due to man-made interference, ionospheric distortion and almost complete non-transparency of the ionosphere below 10 MHz. Therefore, this narrow spectral band remains possibly the last unexplored frequency range in radio astronomy. A straightforward solution to study the universe at these frequencies is to deploy a space-based antenna array far away from Earths' ionosphere. In the past, such space-based radio astronomy studies were principally limited by technology and computing resources, however current processing and communication trends indicate otherwise. Furthermore, successful space-based missions which mapped the sky in this frequency regime, such as the lunar orbiter RAE-2, were restricted by very poor spatial resolution. Recently concluded studies, such as DARIS (Disturbuted Aperture Array for Radio Astronomy In Space) have shown the ready feasibility of a 9 satellite constellation using off the shelf components. The aim of this article is to discuss the current trends and technologies towards the feasibility of a space-based aperture array for astronomical observations in the Ultra-Long Wavelength (ULW) regime of greater than 10 m i.e., below 30 MHz. We briefly present the achievable science cases, and discuss the system design for selected scenarios such as extra-galactic surveys. An extensive discussion is presented on various sub-systems of the potential satellite array, such as radio astronomical antenna design, the on-board signal processing, communication architectures and joint space-time estimation of the satellite network. In light of a scalable array and to avert single point of failure, we propose both centralized and distributed solutions for the ULW space-based array. We highlight the benefits of various deployment locations and summarize the technological challenges for future space-based radio arrays.

show abstract

Section: Previous Studiesmentioning

confidence: 99%

Space-based aperture array for ultra-long wavelength radio astronomy

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Based on the fact that electromagnetic signals are easier to detect than gravitational ones of the same power, we will be looking for a spectral signature of GW-generated Alfvén waves. As is wellknown, the gravitational sources have high powers only up to frequencies of the order ∼ 1kHz, which is much below the lowest observable radio frequencies [21,22]. Thus for GW induced radio wave detection to be possible, we will need a mechanism to convert some fraction of the electromagnetic energy to higher frequencies.…”

Section: Astrophysical Examplementioning

confidence: 99%

“…Unfortunately, this is still not enough to reach the radio window for earth based antennas, where the lower cut-off lies around 20MHz. However, proposals such as the Astronomical Low Frequency Array (ALFA) [21] and more recently the Solar Imaging Radio Array (SIRA) [22] show that satellite based antennas can provide an opening for observation, since such arrays are planned for a sensitivity down to frequencies of the order 30kHz. As shown in Fig.…”

Section: Wave Steepening Zonementioning

confidence: 99%

See 1 more Smart Citation

Harmonic generation of gravitational wave induced Alfvén waves

Forsberg

Brodin

2008

Phys. Rev. D

View full text Add to dashboard Cite

Here we consider the nonlinear evolution of Alfvén waves that have been excited by gravitational waves from merging binary pulsars. We derive a wave equation for strongly nonlinear and dispersive Alfvén waves. Due to the weak dispersion of the Alfvén waves, significant wave steepening can occur, which in turn implies strong harmonic generation. We find that the harmonic generation is saturated due to dispersive effects, and use this to estimate the resulting spectrum. Finally we discuss the possibility of observing the above process.PACS 04.30. Nk, 52.35.Mw, 95.30.Sf

show abstract

“…To reach even lower frequencies, where ionospheric absorption is very intense, space-based instruments are required. The proposed Astronomical Low Frequency Array (ALFA) [23] should reach down to ∼ 0.3 MHz.…”

Section: The Synchrotron Emissionmentioning

confidence: 99%