posted: February 18, 2015

It's a good day when, within the space of 10 hours, two satellites successfully get launched. That's indeed what happened on 11 February when first, at 13:40UT, the Intermediate eXperimental Vehicle (IXV) lifted off with a Vega rocket from French Guyana. This was quickly followed by the launch of the Deep Space Climate Observatory (DSCOVR), lifting off at 23:03UT with a Falcon rocket from Cape Canaveral, Florida.

IXV is an experimental project to provide Europe with an autonomous re-entry capability for future reusable space transportation. The vehicle looks like a wingless plane, has the size of a car, and the weight of a rhino. Hitchhiking the VEGA rocket to a height of 340 km, the unmanned craft then flew all by itself to a maximum altitude of 412 km, which is slightly higher than the operating altitude of the International Space Station. From there, it graciously glided through the Earth's atmosphere withstanding scorching temperatures up to 1700 degrees before successfully splashing down in the Pacific awaiting recovery. During its 100 minutes flight, sensors and cameras were gathering data of the technologies that were tested, for further study and integration into the ongoing project.

Interestingly, Europe's Space weather Coordination Centre (SSCC) in Brussels, Belgium, provided the Space Weather support for this mission. Based on input from BISA and the Regional Warning Centre (RWC) in Brussels, three space weather reports were sent, with the last one just hours before the actual launch. Each of the reports focused on solar flaring activity and any possible proton increases. Such events are known to cause communication problems and glitches in the electronics. Fortunately, the Sun behaved and did not unleash any strong eruption, perfectly in accordance with the forecasts.

Hardly recovered from this adrenaline pumping mission, space enthusiasts got treated to the launch of a very important satellite. Indeed, it is little known that all our realtime knowledge of the solar wind depends pretty much on a single satellite, the Advanced Composition Explorer (ACE). Launched on 25 August 1997, its nominal lifetime was initially set at 5 years. As it turns out, ACE has survived the Sun's furies for a much longer time than that. It is still very much alive and operational, having become a critical asset in the domain of space weather forecasting. As it would be risky business to count on this craft lasting for another 5 to 10 years, a suitable replacement has been developed by NOAA, NASA and USAF. This is the DSCOVR mission, and it will measure all kinds of solar wind features from the same vantage point as ACE, 1.5 million km upstream between the Earth and the Sun. DSCOVR is expected to get there within about 110 days, after which it will have to complete a series of initialization checks. It is hoped that within 150 days (let's say during the summer holidays) the satellite will be fully operational and become the prime solar wind satellite. From this crow's nest (officially called Lagrange-1 point), DSCOVR will then act as the ultimate warning post for the imminent approach of any coronal mass ejection.

Unlike ACE, DSCOVR will also have the capability to observe the Earth. It has two dedicated instruments to do this: EPIC (Earth Polychromatic Imaging Camera) and NISTAR (National Institute of Standards and Technology Advanced Radiometer). EPIC will take pictures from the sunlit face of the Earth in 10 narrow wavelength bands ranging from the ultra violet to the near infrared. Imagery taken by this 30.5 cm Cassegrain telescope will allow research on aerosols, ozone, and cloud height. NISTAR is built to measure the irradiance of the sunlit face of the Earth. This data is to be used to study changes in Earth's radiation budget caused by natural and human activities. Hence, it is expected that both instruments will make valuable contributions to Earth's climate studies.

More information on these missions can be found resp. at ESA's IXV webpage, and at NOAA's DSCOVR page.