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ATV

Scientific objectives

The final moments of ATV-1 "Jules Verne" will be observed in detail by a joint ESA-NASA airborne observation campaign. This will record the spacecraft's reentry with a range of instruments in order to determine how the ATV breaks up as it passes through the Earth's atmosphere. This information is invaluable for comparing with previously developed computer models of the ATV reentry, which will help to enhance safety assessments of future reentries of the ATV and other ESA and NASA spacecraft.

Figure 1 (right): ATV is a new and larger unmanned re-supply ship for the International Space Station. Inset shows the Russian re-supply ship Progress. Photo: ESA. [ESA ATV website]

In their top 10 list of "Astronomy news stories of 2007" last December, Astronomy magazine added a section "News stories to watch in 2008". First on their list: the European Space Agency's new Automated Transfer Vehicle (ATV).

ATV is the first new space craft in a long time, with a function similar to that of the Russian Progress, a re-supply ship for the International Space Station (ISS). ESA spec sheet [pdf]. It is Europe's contribution to the upkeep of the ISS and future ATV launches are planned for once a year or so. On February 22, the very first ATV called "Jules Verne" is scheduled for launch. It will dock with the ISS in March, then undock some time in the late July - late September timeframe for a controlled reentry over the south Pacific Ocean.

The ATV reentry will be quite spectacular. The 13-ton object will enter at about 7.6 km/s, creating a multi-colored fireball with a series of catastrophic fragmentation events and a shower of blue and yellow fragments. The entry path is long, the whole event lasting about four minutes. The reentry is visible in its entirety from an aircraft at altitude, because of low extinction near the horizon.

Both ESA and NASA are keen to observe the re-entry to better understand how the spacecraft breaks appart during entry. The main uncertainties in fragmentation models such as SCARAB concern the timing of the disruptions of the fuel tanks and their effect on the overall breakup.

The SETI Institute is coordinating the science team. We have the expertise to observe this reentry, based on past airborne observing campaigns for the Stardust Sample Return Capsule entry and the Aurigid and Quadrantid MAC missions. We can measure the timing of breakup and explosion events and identify the fragments from their brightness, deceleration, and spectral properties.

MIR Reentry
Figure 2 (below): The reentry of the MIR space station on 2001 March 23, as observed from Fiji. A private airborne mission with two small aircraft failed to observe the reentry because MIR's final de-orbit burn was longer than planned and the station entered earlier along its approach trajectory. [Other reentry images.]

Mission profile

The nominal mission would consist of two aircraft for stereoscopic measurements (and ability to adjust to overboost or underboost entry scenarios), one positioned sideways of the center of the entry track and one sideways of the end (approach view).

This will be a short 5-day trip. We will plan to deploy from NASA Ames two days ahead of time to Tahiti (fly during night time for practice). We plan to have one evening for tarmac calibrations of the instruments. In the morning of the entry, we will deploy to the staging area in the south Pacific to observe the reentry. One day will be reserved in case of a delay in the reentry. The next day, we will return to California.

This will be a controlled reentry. A first de-orbit burn will change the orbit of ATV from a near-circle into an ellipse, with its lowest point dipping into the higher regions of Earth's atmosphere. There can not be much delay after that. A second de-orbit burn would initiate the reentry. If a delay happens after this second de-orbit burn, when we are close to the observing location, then a second attempt requires a full 9h mission out of Tahiti the next day. During the mission, we plan to be in contact with the ATV control center in Toulouse for latest updates on the undocking sequence.

Update: pre-event predictions of brightness and radiation signatures

Pre-flight predictions
Preflight predictions of ATV brightness by I. Boyd (U. of Michigan Ann Arbor) and P. Jenniskens (SETI Institute). Photo: P. Jenniskens/SETI Institute. [click on picture for larger view]

2008 September 09 - Iain Boyd of the University of Michigan at Ann Arbor has completed a study of the expected brightness of ATV at different wavelengths. He assumed that ATV did not tumble (as it will), was cylindrical in shape and entered Earth's atmosphere front side forwards, and did not fragment (as it is expected to do). Full Report. Results have been corrected for range (provided by J. Albers) and atmospheric extinction by P. Jenniskens, SETI Institute. In the figure above, he compares the result to the 548-nm brightness of Stardust at different times along its entry trajectory. Jenniskens also adds that Aluminum Oxyde bands will likely be observed, as shown in a spectrum of the impact flash from a meteorite being bomparded by an aluminum projectile (inset). A publication is in preparation. For now, this data can be used to estimate the exposure times during ATV observations.


SETI Institute logo Curator: Peter Jenniskens
Responsible NASA Official: Dave Jordan
Responsible ESA Official: Jason Hatton

Last update: July 01, 2008


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